mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
2768 lines
93 KiB
2768 lines
93 KiB
.. SPDX-License-Identifier: GPL-2.0 |
|
|
|
========= |
|
IP Sysctl |
|
========= |
|
|
|
/proc/sys/net/ipv4/* Variables |
|
============================== |
|
|
|
ip_forward - BOOLEAN |
|
- 0 - disabled (default) |
|
- not 0 - enabled |
|
|
|
Forward Packets between interfaces. |
|
|
|
This variable is special, its change resets all configuration |
|
parameters to their default state (RFC1122 for hosts, RFC1812 |
|
for routers) |
|
|
|
ip_default_ttl - INTEGER |
|
Default value of TTL field (Time To Live) for outgoing (but not |
|
forwarded) IP packets. Should be between 1 and 255 inclusive. |
|
Default: 64 (as recommended by RFC1700) |
|
|
|
ip_no_pmtu_disc - INTEGER |
|
Disable Path MTU Discovery. If enabled in mode 1 and a |
|
fragmentation-required ICMP is received, the PMTU to this |
|
destination will be set to min_pmtu (see below). You will need |
|
to raise min_pmtu to the smallest interface MTU on your system |
|
manually if you want to avoid locally generated fragments. |
|
|
|
In mode 2 incoming Path MTU Discovery messages will be |
|
discarded. Outgoing frames are handled the same as in mode 1, |
|
implicitly setting IP_PMTUDISC_DONT on every created socket. |
|
|
|
Mode 3 is a hardened pmtu discover mode. The kernel will only |
|
accept fragmentation-needed errors if the underlying protocol |
|
can verify them besides a plain socket lookup. Current |
|
protocols for which pmtu events will be honored are TCP, SCTP |
|
and DCCP as they verify e.g. the sequence number or the |
|
association. This mode should not be enabled globally but is |
|
only intended to secure e.g. name servers in namespaces where |
|
TCP path mtu must still work but path MTU information of other |
|
protocols should be discarded. If enabled globally this mode |
|
could break other protocols. |
|
|
|
Possible values: 0-3 |
|
|
|
Default: FALSE |
|
|
|
min_pmtu - INTEGER |
|
default 552 - minimum discovered Path MTU |
|
|
|
ip_forward_use_pmtu - BOOLEAN |
|
By default we don't trust protocol path MTUs while forwarding |
|
because they could be easily forged and can lead to unwanted |
|
fragmentation by the router. |
|
You only need to enable this if you have user-space software |
|
which tries to discover path mtus by itself and depends on the |
|
kernel honoring this information. This is normally not the |
|
case. |
|
|
|
Default: 0 (disabled) |
|
|
|
Possible values: |
|
|
|
- 0 - disabled |
|
- 1 - enabled |
|
|
|
fwmark_reflect - BOOLEAN |
|
Controls the fwmark of kernel-generated IPv4 reply packets that are not |
|
associated with a socket for example, TCP RSTs or ICMP echo replies). |
|
If unset, these packets have a fwmark of zero. If set, they have the |
|
fwmark of the packet they are replying to. |
|
|
|
Default: 0 |
|
|
|
fib_multipath_use_neigh - BOOLEAN |
|
Use status of existing neighbor entry when determining nexthop for |
|
multipath routes. If disabled, neighbor information is not used and |
|
packets could be directed to a failed nexthop. Only valid for kernels |
|
built with CONFIG_IP_ROUTE_MULTIPATH enabled. |
|
|
|
Default: 0 (disabled) |
|
|
|
Possible values: |
|
|
|
- 0 - disabled |
|
- 1 - enabled |
|
|
|
fib_multipath_hash_policy - INTEGER |
|
Controls which hash policy to use for multipath routes. Only valid |
|
for kernels built with CONFIG_IP_ROUTE_MULTIPATH enabled. |
|
|
|
Default: 0 (Layer 3) |
|
|
|
Possible values: |
|
|
|
- 0 - Layer 3 |
|
- 1 - Layer 4 |
|
- 2 - Layer 3 or inner Layer 3 if present |
|
|
|
fib_sync_mem - UNSIGNED INTEGER |
|
Amount of dirty memory from fib entries that can be backlogged before |
|
synchronize_rcu is forced. |
|
|
|
Default: 512kB Minimum: 64kB Maximum: 64MB |
|
|
|
ip_forward_update_priority - INTEGER |
|
Whether to update SKB priority from "TOS" field in IPv4 header after it |
|
is forwarded. The new SKB priority is mapped from TOS field value |
|
according to an rt_tos2priority table (see e.g. man tc-prio). |
|
|
|
Default: 1 (Update priority.) |
|
|
|
Possible values: |
|
|
|
- 0 - Do not update priority. |
|
- 1 - Update priority. |
|
|
|
route/max_size - INTEGER |
|
Maximum number of routes allowed in the kernel. Increase |
|
this when using large numbers of interfaces and/or routes. |
|
|
|
From linux kernel 3.6 onwards, this is deprecated for ipv4 |
|
as route cache is no longer used. |
|
|
|
neigh/default/gc_thresh1 - INTEGER |
|
Minimum number of entries to keep. Garbage collector will not |
|
purge entries if there are fewer than this number. |
|
|
|
Default: 128 |
|
|
|
neigh/default/gc_thresh2 - INTEGER |
|
Threshold when garbage collector becomes more aggressive about |
|
purging entries. Entries older than 5 seconds will be cleared |
|
when over this number. |
|
|
|
Default: 512 |
|
|
|
neigh/default/gc_thresh3 - INTEGER |
|
Maximum number of non-PERMANENT neighbor entries allowed. Increase |
|
this when using large numbers of interfaces and when communicating |
|
with large numbers of directly-connected peers. |
|
|
|
Default: 1024 |
|
|
|
neigh/default/unres_qlen_bytes - INTEGER |
|
The maximum number of bytes which may be used by packets |
|
queued for each unresolved address by other network layers. |
|
(added in linux 3.3) |
|
|
|
Setting negative value is meaningless and will return error. |
|
|
|
Default: SK_WMEM_MAX, (same as net.core.wmem_default). |
|
|
|
Exact value depends on architecture and kernel options, |
|
but should be enough to allow queuing 256 packets |
|
of medium size. |
|
|
|
neigh/default/unres_qlen - INTEGER |
|
The maximum number of packets which may be queued for each |
|
unresolved address by other network layers. |
|
|
|
(deprecated in linux 3.3) : use unres_qlen_bytes instead. |
|
|
|
Prior to linux 3.3, the default value is 3 which may cause |
|
unexpected packet loss. The current default value is calculated |
|
according to default value of unres_qlen_bytes and true size of |
|
packet. |
|
|
|
Default: 101 |
|
|
|
mtu_expires - INTEGER |
|
Time, in seconds, that cached PMTU information is kept. |
|
|
|
min_adv_mss - INTEGER |
|
The advertised MSS depends on the first hop route MTU, but will |
|
never be lower than this setting. |
|
|
|
fib_notify_on_flag_change - INTEGER |
|
Whether to emit RTM_NEWROUTE notifications whenever RTM_F_OFFLOAD/ |
|
RTM_F_TRAP/RTM_F_OFFLOAD_FAILED flags are changed. |
|
|
|
After installing a route to the kernel, user space receives an |
|
acknowledgment, which means the route was installed in the kernel, |
|
but not necessarily in hardware. |
|
It is also possible for a route already installed in hardware to change |
|
its action and therefore its flags. For example, a host route that is |
|
trapping packets can be "promoted" to perform decapsulation following |
|
the installation of an IPinIP/VXLAN tunnel. |
|
The notifications will indicate to user-space the state of the route. |
|
|
|
Default: 0 (Do not emit notifications.) |
|
|
|
Possible values: |
|
|
|
- 0 - Do not emit notifications. |
|
- 1 - Emit notifications. |
|
- 2 - Emit notifications only for RTM_F_OFFLOAD_FAILED flag change. |
|
|
|
IP Fragmentation: |
|
|
|
ipfrag_high_thresh - LONG INTEGER |
|
Maximum memory used to reassemble IP fragments. |
|
|
|
ipfrag_low_thresh - LONG INTEGER |
|
(Obsolete since linux-4.17) |
|
Maximum memory used to reassemble IP fragments before the kernel |
|
begins to remove incomplete fragment queues to free up resources. |
|
The kernel still accepts new fragments for defragmentation. |
|
|
|
ipfrag_time - INTEGER |
|
Time in seconds to keep an IP fragment in memory. |
|
|
|
ipfrag_max_dist - INTEGER |
|
ipfrag_max_dist is a non-negative integer value which defines the |
|
maximum "disorder" which is allowed among fragments which share a |
|
common IP source address. Note that reordering of packets is |
|
not unusual, but if a large number of fragments arrive from a source |
|
IP address while a particular fragment queue remains incomplete, it |
|
probably indicates that one or more fragments belonging to that queue |
|
have been lost. When ipfrag_max_dist is positive, an additional check |
|
is done on fragments before they are added to a reassembly queue - if |
|
ipfrag_max_dist (or more) fragments have arrived from a particular IP |
|
address between additions to any IP fragment queue using that source |
|
address, it's presumed that one or more fragments in the queue are |
|
lost. The existing fragment queue will be dropped, and a new one |
|
started. An ipfrag_max_dist value of zero disables this check. |
|
|
|
Using a very small value, e.g. 1 or 2, for ipfrag_max_dist can |
|
result in unnecessarily dropping fragment queues when normal |
|
reordering of packets occurs, which could lead to poor application |
|
performance. Using a very large value, e.g. 50000, increases the |
|
likelihood of incorrectly reassembling IP fragments that originate |
|
from different IP datagrams, which could result in data corruption. |
|
Default: 64 |
|
|
|
INET peer storage |
|
================= |
|
|
|
inet_peer_threshold - INTEGER |
|
The approximate size of the storage. Starting from this threshold |
|
entries will be thrown aggressively. This threshold also determines |
|
entries' time-to-live and time intervals between garbage collection |
|
passes. More entries, less time-to-live, less GC interval. |
|
|
|
inet_peer_minttl - INTEGER |
|
Minimum time-to-live of entries. Should be enough to cover fragment |
|
time-to-live on the reassembling side. This minimum time-to-live is |
|
guaranteed if the pool size is less than inet_peer_threshold. |
|
Measured in seconds. |
|
|
|
inet_peer_maxttl - INTEGER |
|
Maximum time-to-live of entries. Unused entries will expire after |
|
this period of time if there is no memory pressure on the pool (i.e. |
|
when the number of entries in the pool is very small). |
|
Measured in seconds. |
|
|
|
TCP variables |
|
============= |
|
|
|
somaxconn - INTEGER |
|
Limit of socket listen() backlog, known in userspace as SOMAXCONN. |
|
Defaults to 4096. (Was 128 before linux-5.4) |
|
See also tcp_max_syn_backlog for additional tuning for TCP sockets. |
|
|
|
tcp_abort_on_overflow - BOOLEAN |
|
If listening service is too slow to accept new connections, |
|
reset them. Default state is FALSE. It means that if overflow |
|
occurred due to a burst, connection will recover. Enable this |
|
option _only_ if you are really sure that listening daemon |
|
cannot be tuned to accept connections faster. Enabling this |
|
option can harm clients of your server. |
|
|
|
tcp_adv_win_scale - INTEGER |
|
Count buffering overhead as bytes/2^tcp_adv_win_scale |
|
(if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale), |
|
if it is <= 0. |
|
|
|
Possible values are [-31, 31], inclusive. |
|
|
|
Default: 1 |
|
|
|
tcp_allowed_congestion_control - STRING |
|
Show/set the congestion control choices available to non-privileged |
|
processes. The list is a subset of those listed in |
|
tcp_available_congestion_control. |
|
|
|
Default is "reno" and the default setting (tcp_congestion_control). |
|
|
|
tcp_app_win - INTEGER |
|
Reserve max(window/2^tcp_app_win, mss) of window for application |
|
buffer. Value 0 is special, it means that nothing is reserved. |
|
|
|
Default: 31 |
|
|
|
tcp_autocorking - BOOLEAN |
|
Enable TCP auto corking : |
|
When applications do consecutive small write()/sendmsg() system calls, |
|
we try to coalesce these small writes as much as possible, to lower |
|
total amount of sent packets. This is done if at least one prior |
|
packet for the flow is waiting in Qdisc queues or device transmit |
|
queue. Applications can still use TCP_CORK for optimal behavior |
|
when they know how/when to uncork their sockets. |
|
|
|
Default : 1 |
|
|
|
tcp_available_congestion_control - STRING |
|
Shows the available congestion control choices that are registered. |
|
More congestion control algorithms may be available as modules, |
|
but not loaded. |
|
|
|
tcp_base_mss - INTEGER |
|
The initial value of search_low to be used by the packetization layer |
|
Path MTU discovery (MTU probing). If MTU probing is enabled, |
|
this is the initial MSS used by the connection. |
|
|
|
tcp_mtu_probe_floor - INTEGER |
|
If MTU probing is enabled this caps the minimum MSS used for search_low |
|
for the connection. |
|
|
|
Default : 48 |
|
|
|
tcp_min_snd_mss - INTEGER |
|
TCP SYN and SYNACK messages usually advertise an ADVMSS option, |
|
as described in RFC 1122 and RFC 6691. |
|
|
|
If this ADVMSS option is smaller than tcp_min_snd_mss, |
|
it is silently capped to tcp_min_snd_mss. |
|
|
|
Default : 48 (at least 8 bytes of payload per segment) |
|
|
|
tcp_congestion_control - STRING |
|
Set the congestion control algorithm to be used for new |
|
connections. The algorithm "reno" is always available, but |
|
additional choices may be available based on kernel configuration. |
|
Default is set as part of kernel configuration. |
|
For passive connections, the listener congestion control choice |
|
is inherited. |
|
|
|
[see setsockopt(listenfd, SOL_TCP, TCP_CONGESTION, "name" ...) ] |
|
|
|
tcp_dsack - BOOLEAN |
|
Allows TCP to send "duplicate" SACKs. |
|
|
|
tcp_early_retrans - INTEGER |
|
Tail loss probe (TLP) converts RTOs occurring due to tail |
|
losses into fast recovery (draft-ietf-tcpm-rack). Note that |
|
TLP requires RACK to function properly (see tcp_recovery below) |
|
|
|
Possible values: |
|
|
|
- 0 disables TLP |
|
- 3 or 4 enables TLP |
|
|
|
Default: 3 |
|
|
|
tcp_ecn - INTEGER |
|
Control use of Explicit Congestion Notification (ECN) by TCP. |
|
ECN is used only when both ends of the TCP connection indicate |
|
support for it. This feature is useful in avoiding losses due |
|
to congestion by allowing supporting routers to signal |
|
congestion before having to drop packets. |
|
|
|
Possible values are: |
|
|
|
= ===================================================== |
|
0 Disable ECN. Neither initiate nor accept ECN. |
|
1 Enable ECN when requested by incoming connections and |
|
also request ECN on outgoing connection attempts. |
|
2 Enable ECN when requested by incoming connections |
|
but do not request ECN on outgoing connections. |
|
= ===================================================== |
|
|
|
Default: 2 |
|
|
|
tcp_ecn_fallback - BOOLEAN |
|
If the kernel detects that ECN connection misbehaves, enable fall |
|
back to non-ECN. Currently, this knob implements the fallback |
|
from RFC3168, section 6.1.1.1., but we reserve that in future, |
|
additional detection mechanisms could be implemented under this |
|
knob. The value is not used, if tcp_ecn or per route (or congestion |
|
control) ECN settings are disabled. |
|
|
|
Default: 1 (fallback enabled) |
|
|
|
tcp_fack - BOOLEAN |
|
This is a legacy option, it has no effect anymore. |
|
|
|
tcp_fin_timeout - INTEGER |
|
The length of time an orphaned (no longer referenced by any |
|
application) connection will remain in the FIN_WAIT_2 state |
|
before it is aborted at the local end. While a perfectly |
|
valid "receive only" state for an un-orphaned connection, an |
|
orphaned connection in FIN_WAIT_2 state could otherwise wait |
|
forever for the remote to close its end of the connection. |
|
|
|
Cf. tcp_max_orphans |
|
|
|
Default: 60 seconds |
|
|
|
tcp_frto - INTEGER |
|
Enables Forward RTO-Recovery (F-RTO) defined in RFC5682. |
|
F-RTO is an enhanced recovery algorithm for TCP retransmission |
|
timeouts. It is particularly beneficial in networks where the |
|
RTT fluctuates (e.g., wireless). F-RTO is sender-side only |
|
modification. It does not require any support from the peer. |
|
|
|
By default it's enabled with a non-zero value. 0 disables F-RTO. |
|
|
|
tcp_fwmark_accept - BOOLEAN |
|
If set, incoming connections to listening sockets that do not have a |
|
socket mark will set the mark of the accepting socket to the fwmark of |
|
the incoming SYN packet. This will cause all packets on that connection |
|
(starting from the first SYNACK) to be sent with that fwmark. The |
|
listening socket's mark is unchanged. Listening sockets that already |
|
have a fwmark set via setsockopt(SOL_SOCKET, SO_MARK, ...) are |
|
unaffected. |
|
|
|
Default: 0 |
|
|
|
tcp_invalid_ratelimit - INTEGER |
|
Limit the maximal rate for sending duplicate acknowledgments |
|
in response to incoming TCP packets that are for an existing |
|
connection but that are invalid due to any of these reasons: |
|
|
|
(a) out-of-window sequence number, |
|
(b) out-of-window acknowledgment number, or |
|
(c) PAWS (Protection Against Wrapped Sequence numbers) check failure |
|
|
|
This can help mitigate simple "ack loop" DoS attacks, wherein |
|
a buggy or malicious middlebox or man-in-the-middle can |
|
rewrite TCP header fields in manner that causes each endpoint |
|
to think that the other is sending invalid TCP segments, thus |
|
causing each side to send an unterminating stream of duplicate |
|
acknowledgments for invalid segments. |
|
|
|
Using 0 disables rate-limiting of dupacks in response to |
|
invalid segments; otherwise this value specifies the minimal |
|
space between sending such dupacks, in milliseconds. |
|
|
|
Default: 500 (milliseconds). |
|
|
|
tcp_keepalive_time - INTEGER |
|
How often TCP sends out keepalive messages when keepalive is enabled. |
|
Default: 2hours. |
|
|
|
tcp_keepalive_probes - INTEGER |
|
How many keepalive probes TCP sends out, until it decides that the |
|
connection is broken. Default value: 9. |
|
|
|
tcp_keepalive_intvl - INTEGER |
|
How frequently the probes are send out. Multiplied by |
|
tcp_keepalive_probes it is time to kill not responding connection, |
|
after probes started. Default value: 75sec i.e. connection |
|
will be aborted after ~11 minutes of retries. |
|
|
|
tcp_l3mdev_accept - BOOLEAN |
|
Enables child sockets to inherit the L3 master device index. |
|
Enabling this option allows a "global" listen socket to work |
|
across L3 master domains (e.g., VRFs) with connected sockets |
|
derived from the listen socket to be bound to the L3 domain in |
|
which the packets originated. Only valid when the kernel was |
|
compiled with CONFIG_NET_L3_MASTER_DEV. |
|
|
|
Default: 0 (disabled) |
|
|
|
tcp_low_latency - BOOLEAN |
|
This is a legacy option, it has no effect anymore. |
|
|
|
tcp_max_orphans - INTEGER |
|
Maximal number of TCP sockets not attached to any user file handle, |
|
held by system. If this number is exceeded orphaned connections are |
|
reset immediately and warning is printed. This limit exists |
|
only to prevent simple DoS attacks, you _must_ not rely on this |
|
or lower the limit artificially, but rather increase it |
|
(probably, after increasing installed memory), |
|
if network conditions require more than default value, |
|
and tune network services to linger and kill such states |
|
more aggressively. Let me to remind again: each orphan eats |
|
up to ~64K of unswappable memory. |
|
|
|
tcp_max_syn_backlog - INTEGER |
|
Maximal number of remembered connection requests (SYN_RECV), |
|
which have not received an acknowledgment from connecting client. |
|
|
|
This is a per-listener limit. |
|
|
|
The minimal value is 128 for low memory machines, and it will |
|
increase in proportion to the memory of machine. |
|
|
|
If server suffers from overload, try increasing this number. |
|
|
|
Remember to also check /proc/sys/net/core/somaxconn |
|
A SYN_RECV request socket consumes about 304 bytes of memory. |
|
|
|
tcp_max_tw_buckets - INTEGER |
|
Maximal number of timewait sockets held by system simultaneously. |
|
If this number is exceeded time-wait socket is immediately destroyed |
|
and warning is printed. This limit exists only to prevent |
|
simple DoS attacks, you _must_ not lower the limit artificially, |
|
but rather increase it (probably, after increasing installed memory), |
|
if network conditions require more than default value. |
|
|
|
tcp_mem - vector of 3 INTEGERs: min, pressure, max |
|
min: below this number of pages TCP is not bothered about its |
|
memory appetite. |
|
|
|
pressure: when amount of memory allocated by TCP exceeds this number |
|
of pages, TCP moderates its memory consumption and enters memory |
|
pressure mode, which is exited when memory consumption falls |
|
under "min". |
|
|
|
max: number of pages allowed for queueing by all TCP sockets. |
|
|
|
Defaults are calculated at boot time from amount of available |
|
memory. |
|
|
|
tcp_min_rtt_wlen - INTEGER |
|
The window length of the windowed min filter to track the minimum RTT. |
|
A shorter window lets a flow more quickly pick up new (higher) |
|
minimum RTT when it is moved to a longer path (e.g., due to traffic |
|
engineering). A longer window makes the filter more resistant to RTT |
|
inflations such as transient congestion. The unit is seconds. |
|
|
|
Possible values: 0 - 86400 (1 day) |
|
|
|
Default: 300 |
|
|
|
tcp_moderate_rcvbuf - BOOLEAN |
|
If set, TCP performs receive buffer auto-tuning, attempting to |
|
automatically size the buffer (no greater than tcp_rmem[2]) to |
|
match the size required by the path for full throughput. Enabled by |
|
default. |
|
|
|
tcp_mtu_probing - INTEGER |
|
Controls TCP Packetization-Layer Path MTU Discovery. Takes three |
|
values: |
|
|
|
- 0 - Disabled |
|
- 1 - Disabled by default, enabled when an ICMP black hole detected |
|
- 2 - Always enabled, use initial MSS of tcp_base_mss. |
|
|
|
tcp_probe_interval - UNSIGNED INTEGER |
|
Controls how often to start TCP Packetization-Layer Path MTU |
|
Discovery reprobe. The default is reprobing every 10 minutes as |
|
per RFC4821. |
|
|
|
tcp_probe_threshold - INTEGER |
|
Controls when TCP Packetization-Layer Path MTU Discovery probing |
|
will stop in respect to the width of search range in bytes. Default |
|
is 8 bytes. |
|
|
|
tcp_no_metrics_save - BOOLEAN |
|
By default, TCP saves various connection metrics in the route cache |
|
when the connection closes, so that connections established in the |
|
near future can use these to set initial conditions. Usually, this |
|
increases overall performance, but may sometimes cause performance |
|
degradation. If set, TCP will not cache metrics on closing |
|
connections. |
|
|
|
tcp_no_ssthresh_metrics_save - BOOLEAN |
|
Controls whether TCP saves ssthresh metrics in the route cache. |
|
|
|
Default is 1, which disables ssthresh metrics. |
|
|
|
tcp_orphan_retries - INTEGER |
|
This value influences the timeout of a locally closed TCP connection, |
|
when RTO retransmissions remain unacknowledged. |
|
See tcp_retries2 for more details. |
|
|
|
The default value is 8. |
|
|
|
If your machine is a loaded WEB server, |
|
you should think about lowering this value, such sockets |
|
may consume significant resources. Cf. tcp_max_orphans. |
|
|
|
tcp_recovery - INTEGER |
|
This value is a bitmap to enable various experimental loss recovery |
|
features. |
|
|
|
========= ============================================================= |
|
RACK: 0x1 enables the RACK loss detection for fast detection of lost |
|
retransmissions and tail drops. It also subsumes and disables |
|
RFC6675 recovery for SACK connections. |
|
|
|
RACK: 0x2 makes RACK's reordering window static (min_rtt/4). |
|
|
|
RACK: 0x4 disables RACK's DUPACK threshold heuristic |
|
========= ============================================================= |
|
|
|
Default: 0x1 |
|
|
|
tcp_reordering - INTEGER |
|
Initial reordering level of packets in a TCP stream. |
|
TCP stack can then dynamically adjust flow reordering level |
|
between this initial value and tcp_max_reordering |
|
|
|
Default: 3 |
|
|
|
tcp_max_reordering - INTEGER |
|
Maximal reordering level of packets in a TCP stream. |
|
300 is a fairly conservative value, but you might increase it |
|
if paths are using per packet load balancing (like bonding rr mode) |
|
|
|
Default: 300 |
|
|
|
tcp_retrans_collapse - BOOLEAN |
|
Bug-to-bug compatibility with some broken printers. |
|
On retransmit try to send bigger packets to work around bugs in |
|
certain TCP stacks. |
|
|
|
tcp_retries1 - INTEGER |
|
This value influences the time, after which TCP decides, that |
|
something is wrong due to unacknowledged RTO retransmissions, |
|
and reports this suspicion to the network layer. |
|
See tcp_retries2 for more details. |
|
|
|
RFC 1122 recommends at least 3 retransmissions, which is the |
|
default. |
|
|
|
tcp_retries2 - INTEGER |
|
This value influences the timeout of an alive TCP connection, |
|
when RTO retransmissions remain unacknowledged. |
|
Given a value of N, a hypothetical TCP connection following |
|
exponential backoff with an initial RTO of TCP_RTO_MIN would |
|
retransmit N times before killing the connection at the (N+1)th RTO. |
|
|
|
The default value of 15 yields a hypothetical timeout of 924.6 |
|
seconds and is a lower bound for the effective timeout. |
|
TCP will effectively time out at the first RTO which exceeds the |
|
hypothetical timeout. |
|
|
|
RFC 1122 recommends at least 100 seconds for the timeout, |
|
which corresponds to a value of at least 8. |
|
|
|
tcp_rfc1337 - BOOLEAN |
|
If set, the TCP stack behaves conforming to RFC1337. If unset, |
|
we are not conforming to RFC, but prevent TCP TIME_WAIT |
|
assassination. |
|
|
|
Default: 0 |
|
|
|
tcp_rmem - vector of 3 INTEGERs: min, default, max |
|
min: Minimal size of receive buffer used by TCP sockets. |
|
It is guaranteed to each TCP socket, even under moderate memory |
|
pressure. |
|
|
|
Default: 4K |
|
|
|
default: initial size of receive buffer used by TCP sockets. |
|
This value overrides net.core.rmem_default used by other protocols. |
|
Default: 131072 bytes. |
|
This value results in initial window of 65535. |
|
|
|
max: maximal size of receive buffer allowed for automatically |
|
selected receiver buffers for TCP socket. This value does not override |
|
net.core.rmem_max. Calling setsockopt() with SO_RCVBUF disables |
|
automatic tuning of that socket's receive buffer size, in which |
|
case this value is ignored. |
|
Default: between 131072 and 6MB, depending on RAM size. |
|
|
|
tcp_sack - BOOLEAN |
|
Enable select acknowledgments (SACKS). |
|
|
|
tcp_comp_sack_delay_ns - LONG INTEGER |
|
TCP tries to reduce number of SACK sent, using a timer |
|
based on 5% of SRTT, capped by this sysctl, in nano seconds. |
|
The default is 1ms, based on TSO autosizing period. |
|
|
|
Default : 1,000,000 ns (1 ms) |
|
|
|
tcp_comp_sack_slack_ns - LONG INTEGER |
|
This sysctl control the slack used when arming the |
|
timer used by SACK compression. This gives extra time |
|
for small RTT flows, and reduces system overhead by allowing |
|
opportunistic reduction of timer interrupts. |
|
|
|
Default : 100,000 ns (100 us) |
|
|
|
tcp_comp_sack_nr - INTEGER |
|
Max number of SACK that can be compressed. |
|
Using 0 disables SACK compression. |
|
|
|
Default : 44 |
|
|
|
tcp_slow_start_after_idle - BOOLEAN |
|
If set, provide RFC2861 behavior and time out the congestion |
|
window after an idle period. An idle period is defined at |
|
the current RTO. If unset, the congestion window will not |
|
be timed out after an idle period. |
|
|
|
Default: 1 |
|
|
|
tcp_stdurg - BOOLEAN |
|
Use the Host requirements interpretation of the TCP urgent pointer field. |
|
Most hosts use the older BSD interpretation, so if you turn this on |
|
Linux might not communicate correctly with them. |
|
|
|
Default: FALSE |
|
|
|
tcp_synack_retries - INTEGER |
|
Number of times SYNACKs for a passive TCP connection attempt will |
|
be retransmitted. Should not be higher than 255. Default value |
|
is 5, which corresponds to 31seconds till the last retransmission |
|
with the current initial RTO of 1second. With this the final timeout |
|
for a passive TCP connection will happen after 63seconds. |
|
|
|
tcp_syncookies - INTEGER |
|
Only valid when the kernel was compiled with CONFIG_SYN_COOKIES |
|
Send out syncookies when the syn backlog queue of a socket |
|
overflows. This is to prevent against the common 'SYN flood attack' |
|
Default: 1 |
|
|
|
Note, that syncookies is fallback facility. |
|
It MUST NOT be used to help highly loaded servers to stand |
|
against legal connection rate. If you see SYN flood warnings |
|
in your logs, but investigation shows that they occur |
|
because of overload with legal connections, you should tune |
|
another parameters until this warning disappear. |
|
See: tcp_max_syn_backlog, tcp_synack_retries, tcp_abort_on_overflow. |
|
|
|
syncookies seriously violate TCP protocol, do not allow |
|
to use TCP extensions, can result in serious degradation |
|
of some services (f.e. SMTP relaying), visible not by you, |
|
but your clients and relays, contacting you. While you see |
|
SYN flood warnings in logs not being really flooded, your server |
|
is seriously misconfigured. |
|
|
|
If you want to test which effects syncookies have to your |
|
network connections you can set this knob to 2 to enable |
|
unconditionally generation of syncookies. |
|
|
|
tcp_fastopen - INTEGER |
|
Enable TCP Fast Open (RFC7413) to send and accept data in the opening |
|
SYN packet. |
|
|
|
The client support is enabled by flag 0x1 (on by default). The client |
|
then must use sendmsg() or sendto() with the MSG_FASTOPEN flag, |
|
rather than connect() to send data in SYN. |
|
|
|
The server support is enabled by flag 0x2 (off by default). Then |
|
either enable for all listeners with another flag (0x400) or |
|
enable individual listeners via TCP_FASTOPEN socket option with |
|
the option value being the length of the syn-data backlog. |
|
|
|
The values (bitmap) are |
|
|
|
===== ======== ====================================================== |
|
0x1 (client) enables sending data in the opening SYN on the client. |
|
0x2 (server) enables the server support, i.e., allowing data in |
|
a SYN packet to be accepted and passed to the |
|
application before 3-way handshake finishes. |
|
0x4 (client) send data in the opening SYN regardless of cookie |
|
availability and without a cookie option. |
|
0x200 (server) accept data-in-SYN w/o any cookie option present. |
|
0x400 (server) enable all listeners to support Fast Open by |
|
default without explicit TCP_FASTOPEN socket option. |
|
===== ======== ====================================================== |
|
|
|
Default: 0x1 |
|
|
|
Note that additional client or server features are only |
|
effective if the basic support (0x1 and 0x2) are enabled respectively. |
|
|
|
tcp_fastopen_blackhole_timeout_sec - INTEGER |
|
Initial time period in second to disable Fastopen on active TCP sockets |
|
when a TFO firewall blackhole issue happens. |
|
This time period will grow exponentially when more blackhole issues |
|
get detected right after Fastopen is re-enabled and will reset to |
|
initial value when the blackhole issue goes away. |
|
0 to disable the blackhole detection. |
|
|
|
By default, it is set to 1hr. |
|
|
|
tcp_fastopen_key - list of comma separated 32-digit hexadecimal INTEGERs |
|
The list consists of a primary key and an optional backup key. The |
|
primary key is used for both creating and validating cookies, while the |
|
optional backup key is only used for validating cookies. The purpose of |
|
the backup key is to maximize TFO validation when keys are rotated. |
|
|
|
A randomly chosen primary key may be configured by the kernel if |
|
the tcp_fastopen sysctl is set to 0x400 (see above), or if the |
|
TCP_FASTOPEN setsockopt() optname is set and a key has not been |
|
previously configured via sysctl. If keys are configured via |
|
setsockopt() by using the TCP_FASTOPEN_KEY optname, then those |
|
per-socket keys will be used instead of any keys that are specified via |
|
sysctl. |
|
|
|
A key is specified as 4 8-digit hexadecimal integers which are separated |
|
by a '-' as: xxxxxxxx-xxxxxxxx-xxxxxxxx-xxxxxxxx. Leading zeros may be |
|
omitted. A primary and a backup key may be specified by separating them |
|
by a comma. If only one key is specified, it becomes the primary key and |
|
any previously configured backup keys are removed. |
|
|
|
tcp_syn_retries - INTEGER |
|
Number of times initial SYNs for an active TCP connection attempt |
|
will be retransmitted. Should not be higher than 127. Default value |
|
is 6, which corresponds to 63seconds till the last retransmission |
|
with the current initial RTO of 1second. With this the final timeout |
|
for an active TCP connection attempt will happen after 127seconds. |
|
|
|
tcp_timestamps - INTEGER |
|
Enable timestamps as defined in RFC1323. |
|
|
|
- 0: Disabled. |
|
- 1: Enable timestamps as defined in RFC1323 and use random offset for |
|
each connection rather than only using the current time. |
|
- 2: Like 1, but without random offsets. |
|
|
|
Default: 1 |
|
|
|
tcp_min_tso_segs - INTEGER |
|
Minimal number of segments per TSO frame. |
|
|
|
Since linux-3.12, TCP does an automatic sizing of TSO frames, |
|
depending on flow rate, instead of filling 64Kbytes packets. |
|
For specific usages, it's possible to force TCP to build big |
|
TSO frames. Note that TCP stack might split too big TSO packets |
|
if available window is too small. |
|
|
|
Default: 2 |
|
|
|
tcp_pacing_ss_ratio - INTEGER |
|
sk->sk_pacing_rate is set by TCP stack using a ratio applied |
|
to current rate. (current_rate = cwnd * mss / srtt) |
|
If TCP is in slow start, tcp_pacing_ss_ratio is applied |
|
to let TCP probe for bigger speeds, assuming cwnd can be |
|
doubled every other RTT. |
|
|
|
Default: 200 |
|
|
|
tcp_pacing_ca_ratio - INTEGER |
|
sk->sk_pacing_rate is set by TCP stack using a ratio applied |
|
to current rate. (current_rate = cwnd * mss / srtt) |
|
If TCP is in congestion avoidance phase, tcp_pacing_ca_ratio |
|
is applied to conservatively probe for bigger throughput. |
|
|
|
Default: 120 |
|
|
|
tcp_tso_win_divisor - INTEGER |
|
This allows control over what percentage of the congestion window |
|
can be consumed by a single TSO frame. |
|
The setting of this parameter is a choice between burstiness and |
|
building larger TSO frames. |
|
|
|
Default: 3 |
|
|
|
tcp_tw_reuse - INTEGER |
|
Enable reuse of TIME-WAIT sockets for new connections when it is |
|
safe from protocol viewpoint. |
|
|
|
- 0 - disable |
|
- 1 - global enable |
|
- 2 - enable for loopback traffic only |
|
|
|
It should not be changed without advice/request of technical |
|
experts. |
|
|
|
Default: 2 |
|
|
|
tcp_window_scaling - BOOLEAN |
|
Enable window scaling as defined in RFC1323. |
|
|
|
tcp_wmem - vector of 3 INTEGERs: min, default, max |
|
min: Amount of memory reserved for send buffers for TCP sockets. |
|
Each TCP socket has rights to use it due to fact of its birth. |
|
|
|
Default: 4K |
|
|
|
default: initial size of send buffer used by TCP sockets. This |
|
value overrides net.core.wmem_default used by other protocols. |
|
|
|
It is usually lower than net.core.wmem_default. |
|
|
|
Default: 16K |
|
|
|
max: Maximal amount of memory allowed for automatically tuned |
|
send buffers for TCP sockets. This value does not override |
|
net.core.wmem_max. Calling setsockopt() with SO_SNDBUF disables |
|
automatic tuning of that socket's send buffer size, in which case |
|
this value is ignored. |
|
|
|
Default: between 64K and 4MB, depending on RAM size. |
|
|
|
tcp_notsent_lowat - UNSIGNED INTEGER |
|
A TCP socket can control the amount of unsent bytes in its write queue, |
|
thanks to TCP_NOTSENT_LOWAT socket option. poll()/select()/epoll() |
|
reports POLLOUT events if the amount of unsent bytes is below a per |
|
socket value, and if the write queue is not full. sendmsg() will |
|
also not add new buffers if the limit is hit. |
|
|
|
This global variable controls the amount of unsent data for |
|
sockets not using TCP_NOTSENT_LOWAT. For these sockets, a change |
|
to the global variable has immediate effect. |
|
|
|
Default: UINT_MAX (0xFFFFFFFF) |
|
|
|
tcp_workaround_signed_windows - BOOLEAN |
|
If set, assume no receipt of a window scaling option means the |
|
remote TCP is broken and treats the window as a signed quantity. |
|
If unset, assume the remote TCP is not broken even if we do |
|
not receive a window scaling option from them. |
|
|
|
Default: 0 |
|
|
|
tcp_thin_linear_timeouts - BOOLEAN |
|
Enable dynamic triggering of linear timeouts for thin streams. |
|
If set, a check is performed upon retransmission by timeout to |
|
determine if the stream is thin (less than 4 packets in flight). |
|
As long as the stream is found to be thin, up to 6 linear |
|
timeouts may be performed before exponential backoff mode is |
|
initiated. This improves retransmission latency for |
|
non-aggressive thin streams, often found to be time-dependent. |
|
For more information on thin streams, see |
|
Documentation/networking/tcp-thin.rst |
|
|
|
Default: 0 |
|
|
|
tcp_limit_output_bytes - INTEGER |
|
Controls TCP Small Queue limit per tcp socket. |
|
TCP bulk sender tends to increase packets in flight until it |
|
gets losses notifications. With SNDBUF autotuning, this can |
|
result in a large amount of packets queued on the local machine |
|
(e.g.: qdiscs, CPU backlog, or device) hurting latency of other |
|
flows, for typical pfifo_fast qdiscs. tcp_limit_output_bytes |
|
limits the number of bytes on qdisc or device to reduce artificial |
|
RTT/cwnd and reduce bufferbloat. |
|
|
|
Default: 1048576 (16 * 65536) |
|
|
|
tcp_challenge_ack_limit - INTEGER |
|
Limits number of Challenge ACK sent per second, as recommended |
|
in RFC 5961 (Improving TCP's Robustness to Blind In-Window Attacks) |
|
Default: 1000 |
|
|
|
tcp_rx_skb_cache - BOOLEAN |
|
Controls a per TCP socket cache of one skb, that might help |
|
performance of some workloads. This might be dangerous |
|
on systems with a lot of TCP sockets, since it increases |
|
memory usage. |
|
|
|
Default: 0 (disabled) |
|
|
|
UDP variables |
|
============= |
|
|
|
udp_l3mdev_accept - BOOLEAN |
|
Enabling this option allows a "global" bound socket to work |
|
across L3 master domains (e.g., VRFs) with packets capable of |
|
being received regardless of the L3 domain in which they |
|
originated. Only valid when the kernel was compiled with |
|
CONFIG_NET_L3_MASTER_DEV. |
|
|
|
Default: 0 (disabled) |
|
|
|
udp_mem - vector of 3 INTEGERs: min, pressure, max |
|
Number of pages allowed for queueing by all UDP sockets. |
|
|
|
min: Below this number of pages UDP is not bothered about its |
|
memory appetite. When amount of memory allocated by UDP exceeds |
|
this number, UDP starts to moderate memory usage. |
|
|
|
pressure: This value was introduced to follow format of tcp_mem. |
|
|
|
max: Number of pages allowed for queueing by all UDP sockets. |
|
|
|
Default is calculated at boot time from amount of available memory. |
|
|
|
udp_rmem_min - INTEGER |
|
Minimal size of receive buffer used by UDP sockets in moderation. |
|
Each UDP socket is able to use the size for receiving data, even if |
|
total pages of UDP sockets exceed udp_mem pressure. The unit is byte. |
|
|
|
Default: 4K |
|
|
|
udp_wmem_min - INTEGER |
|
Minimal size of send buffer used by UDP sockets in moderation. |
|
Each UDP socket is able to use the size for sending data, even if |
|
total pages of UDP sockets exceed udp_mem pressure. The unit is byte. |
|
|
|
Default: 4K |
|
|
|
RAW variables |
|
============= |
|
|
|
raw_l3mdev_accept - BOOLEAN |
|
Enabling this option allows a "global" bound socket to work |
|
across L3 master domains (e.g., VRFs) with packets capable of |
|
being received regardless of the L3 domain in which they |
|
originated. Only valid when the kernel was compiled with |
|
CONFIG_NET_L3_MASTER_DEV. |
|
|
|
Default: 1 (enabled) |
|
|
|
CIPSOv4 Variables |
|
================= |
|
|
|
cipso_cache_enable - BOOLEAN |
|
If set, enable additions to and lookups from the CIPSO label mapping |
|
cache. If unset, additions are ignored and lookups always result in a |
|
miss. However, regardless of the setting the cache is still |
|
invalidated when required when means you can safely toggle this on and |
|
off and the cache will always be "safe". |
|
|
|
Default: 1 |
|
|
|
cipso_cache_bucket_size - INTEGER |
|
The CIPSO label cache consists of a fixed size hash table with each |
|
hash bucket containing a number of cache entries. This variable limits |
|
the number of entries in each hash bucket; the larger the value the |
|
more CIPSO label mappings that can be cached. When the number of |
|
entries in a given hash bucket reaches this limit adding new entries |
|
causes the oldest entry in the bucket to be removed to make room. |
|
|
|
Default: 10 |
|
|
|
cipso_rbm_optfmt - BOOLEAN |
|
Enable the "Optimized Tag 1 Format" as defined in section 3.4.2.6 of |
|
the CIPSO draft specification (see Documentation/netlabel for details). |
|
This means that when set the CIPSO tag will be padded with empty |
|
categories in order to make the packet data 32-bit aligned. |
|
|
|
Default: 0 |
|
|
|
cipso_rbm_structvalid - BOOLEAN |
|
If set, do a very strict check of the CIPSO option when |
|
ip_options_compile() is called. If unset, relax the checks done during |
|
ip_options_compile(). Either way is "safe" as errors are caught else |
|
where in the CIPSO processing code but setting this to 0 (False) should |
|
result in less work (i.e. it should be faster) but could cause problems |
|
with other implementations that require strict checking. |
|
|
|
Default: 0 |
|
|
|
IP Variables |
|
============ |
|
|
|
ip_local_port_range - 2 INTEGERS |
|
Defines the local port range that is used by TCP and UDP to |
|
choose the local port. The first number is the first, the |
|
second the last local port number. |
|
If possible, it is better these numbers have different parity |
|
(one even and one odd value). |
|
Must be greater than or equal to ip_unprivileged_port_start. |
|
The default values are 32768 and 60999 respectively. |
|
|
|
ip_local_reserved_ports - list of comma separated ranges |
|
Specify the ports which are reserved for known third-party |
|
applications. These ports will not be used by automatic port |
|
assignments (e.g. when calling connect() or bind() with port |
|
number 0). Explicit port allocation behavior is unchanged. |
|
|
|
The format used for both input and output is a comma separated |
|
list of ranges (e.g. "1,2-4,10-10" for ports 1, 2, 3, 4 and |
|
10). Writing to the file will clear all previously reserved |
|
ports and update the current list with the one given in the |
|
input. |
|
|
|
Note that ip_local_port_range and ip_local_reserved_ports |
|
settings are independent and both are considered by the kernel |
|
when determining which ports are available for automatic port |
|
assignments. |
|
|
|
You can reserve ports which are not in the current |
|
ip_local_port_range, e.g.:: |
|
|
|
$ cat /proc/sys/net/ipv4/ip_local_port_range |
|
32000 60999 |
|
$ cat /proc/sys/net/ipv4/ip_local_reserved_ports |
|
8080,9148 |
|
|
|
although this is redundant. However such a setting is useful |
|
if later the port range is changed to a value that will |
|
include the reserved ports. Also keep in mind, that overlapping |
|
of these ranges may affect probability of selecting ephemeral |
|
ports which are right after block of reserved ports. |
|
|
|
Default: Empty |
|
|
|
ip_unprivileged_port_start - INTEGER |
|
This is a per-namespace sysctl. It defines the first |
|
unprivileged port in the network namespace. Privileged ports |
|
require root or CAP_NET_BIND_SERVICE in order to bind to them. |
|
To disable all privileged ports, set this to 0. They must not |
|
overlap with the ip_local_port_range. |
|
|
|
Default: 1024 |
|
|
|
ip_nonlocal_bind - BOOLEAN |
|
If set, allows processes to bind() to non-local IP addresses, |
|
which can be quite useful - but may break some applications. |
|
|
|
Default: 0 |
|
|
|
ip_autobind_reuse - BOOLEAN |
|
By default, bind() does not select the ports automatically even if |
|
the new socket and all sockets bound to the port have SO_REUSEADDR. |
|
ip_autobind_reuse allows bind() to reuse the port and this is useful |
|
when you use bind()+connect(), but may break some applications. |
|
The preferred solution is to use IP_BIND_ADDRESS_NO_PORT and this |
|
option should only be set by experts. |
|
Default: 0 |
|
|
|
ip_dynaddr - BOOLEAN |
|
If set non-zero, enables support for dynamic addresses. |
|
If set to a non-zero value larger than 1, a kernel log |
|
message will be printed when dynamic address rewriting |
|
occurs. |
|
|
|
Default: 0 |
|
|
|
ip_early_demux - BOOLEAN |
|
Optimize input packet processing down to one demux for |
|
certain kinds of local sockets. Currently we only do this |
|
for established TCP and connected UDP sockets. |
|
|
|
It may add an additional cost for pure routing workloads that |
|
reduces overall throughput, in such case you should disable it. |
|
|
|
Default: 1 |
|
|
|
ping_group_range - 2 INTEGERS |
|
Restrict ICMP_PROTO datagram sockets to users in the group range. |
|
The default is "1 0", meaning, that nobody (not even root) may |
|
create ping sockets. Setting it to "100 100" would grant permissions |
|
to the single group. "0 4294967295" would enable it for the world, "100 |
|
4294967295" would enable it for the users, but not daemons. |
|
|
|
tcp_early_demux - BOOLEAN |
|
Enable early demux for established TCP sockets. |
|
|
|
Default: 1 |
|
|
|
udp_early_demux - BOOLEAN |
|
Enable early demux for connected UDP sockets. Disable this if |
|
your system could experience more unconnected load. |
|
|
|
Default: 1 |
|
|
|
icmp_echo_ignore_all - BOOLEAN |
|
If set non-zero, then the kernel will ignore all ICMP ECHO |
|
requests sent to it. |
|
|
|
Default: 0 |
|
|
|
icmp_echo_enable_probe - BOOLEAN |
|
If set to one, then the kernel will respond to RFC 8335 PROBE |
|
requests sent to it. |
|
|
|
Default: 0 |
|
|
|
icmp_echo_ignore_broadcasts - BOOLEAN |
|
If set non-zero, then the kernel will ignore all ICMP ECHO and |
|
TIMESTAMP requests sent to it via broadcast/multicast. |
|
|
|
Default: 1 |
|
|
|
icmp_ratelimit - INTEGER |
|
Limit the maximal rates for sending ICMP packets whose type matches |
|
icmp_ratemask (see below) to specific targets. |
|
0 to disable any limiting, |
|
otherwise the minimal space between responses in milliseconds. |
|
Note that another sysctl, icmp_msgs_per_sec limits the number |
|
of ICMP packets sent on all targets. |
|
|
|
Default: 1000 |
|
|
|
icmp_msgs_per_sec - INTEGER |
|
Limit maximal number of ICMP packets sent per second from this host. |
|
Only messages whose type matches icmp_ratemask (see below) are |
|
controlled by this limit. For security reasons, the precise count |
|
of messages per second is randomized. |
|
|
|
Default: 1000 |
|
|
|
icmp_msgs_burst - INTEGER |
|
icmp_msgs_per_sec controls number of ICMP packets sent per second, |
|
while icmp_msgs_burst controls the burst size of these packets. |
|
For security reasons, the precise burst size is randomized. |
|
|
|
Default: 50 |
|
|
|
icmp_ratemask - INTEGER |
|
Mask made of ICMP types for which rates are being limited. |
|
|
|
Significant bits: IHGFEDCBA9876543210 |
|
|
|
Default mask: 0000001100000011000 (6168) |
|
|
|
Bit definitions (see include/linux/icmp.h): |
|
|
|
= ========================= |
|
0 Echo Reply |
|
3 Destination Unreachable [1]_ |
|
4 Source Quench [1]_ |
|
5 Redirect |
|
8 Echo Request |
|
B Time Exceeded [1]_ |
|
C Parameter Problem [1]_ |
|
D Timestamp Request |
|
E Timestamp Reply |
|
F Info Request |
|
G Info Reply |
|
H Address Mask Request |
|
I Address Mask Reply |
|
= ========================= |
|
|
|
.. [1] These are rate limited by default (see default mask above) |
|
|
|
icmp_ignore_bogus_error_responses - BOOLEAN |
|
Some routers violate RFC1122 by sending bogus responses to broadcast |
|
frames. Such violations are normally logged via a kernel warning. |
|
If this is set to TRUE, the kernel will not give such warnings, which |
|
will avoid log file clutter. |
|
|
|
Default: 1 |
|
|
|
icmp_errors_use_inbound_ifaddr - BOOLEAN |
|
|
|
If zero, icmp error messages are sent with the primary address of |
|
the exiting interface. |
|
|
|
If non-zero, the message will be sent with the primary address of |
|
the interface that received the packet that caused the icmp error. |
|
This is the behaviour many network administrators will expect from |
|
a router. And it can make debugging complicated network layouts |
|
much easier. |
|
|
|
Note that if no primary address exists for the interface selected, |
|
then the primary address of the first non-loopback interface that |
|
has one will be used regardless of this setting. |
|
|
|
Default: 0 |
|
|
|
igmp_max_memberships - INTEGER |
|
Change the maximum number of multicast groups we can subscribe to. |
|
Default: 20 |
|
|
|
Theoretical maximum value is bounded by having to send a membership |
|
report in a single datagram (i.e. the report can't span multiple |
|
datagrams, or risk confusing the switch and leaving groups you don't |
|
intend to). |
|
|
|
The number of supported groups 'M' is bounded by the number of group |
|
report entries you can fit into a single datagram of 65535 bytes. |
|
|
|
M = 65536-sizeof (ip header)/(sizeof(Group record)) |
|
|
|
Group records are variable length, with a minimum of 12 bytes. |
|
So net.ipv4.igmp_max_memberships should not be set higher than: |
|
|
|
(65536-24) / 12 = 5459 |
|
|
|
The value 5459 assumes no IP header options, so in practice |
|
this number may be lower. |
|
|
|
igmp_max_msf - INTEGER |
|
Maximum number of addresses allowed in the source filter list for a |
|
multicast group. |
|
|
|
Default: 10 |
|
|
|
igmp_qrv - INTEGER |
|
Controls the IGMP query robustness variable (see RFC2236 8.1). |
|
|
|
Default: 2 (as specified by RFC2236 8.1) |
|
|
|
Minimum: 1 (as specified by RFC6636 4.5) |
|
|
|
force_igmp_version - INTEGER |
|
- 0 - (default) No enforcement of a IGMP version, IGMPv1/v2 fallback |
|
allowed. Will back to IGMPv3 mode again if all IGMPv1/v2 Querier |
|
Present timer expires. |
|
- 1 - Enforce to use IGMP version 1. Will also reply IGMPv1 report if |
|
receive IGMPv2/v3 query. |
|
- 2 - Enforce to use IGMP version 2. Will fallback to IGMPv1 if receive |
|
IGMPv1 query message. Will reply report if receive IGMPv3 query. |
|
- 3 - Enforce to use IGMP version 3. The same react with default 0. |
|
|
|
.. note:: |
|
|
|
this is not the same with force_mld_version because IGMPv3 RFC3376 |
|
Security Considerations does not have clear description that we could |
|
ignore other version messages completely as MLDv2 RFC3810. So make |
|
this value as default 0 is recommended. |
|
|
|
``conf/interface/*`` |
|
changes special settings per interface (where |
|
interface" is the name of your network interface) |
|
|
|
``conf/all/*`` |
|
is special, changes the settings for all interfaces |
|
|
|
log_martians - BOOLEAN |
|
Log packets with impossible addresses to kernel log. |
|
log_martians for the interface will be enabled if at least one of |
|
conf/{all,interface}/log_martians is set to TRUE, |
|
it will be disabled otherwise |
|
|
|
accept_redirects - BOOLEAN |
|
Accept ICMP redirect messages. |
|
accept_redirects for the interface will be enabled if: |
|
|
|
- both conf/{all,interface}/accept_redirects are TRUE in the case |
|
forwarding for the interface is enabled |
|
|
|
or |
|
|
|
- at least one of conf/{all,interface}/accept_redirects is TRUE in the |
|
case forwarding for the interface is disabled |
|
|
|
accept_redirects for the interface will be disabled otherwise |
|
|
|
default: |
|
|
|
- TRUE (host) |
|
- FALSE (router) |
|
|
|
forwarding - BOOLEAN |
|
Enable IP forwarding on this interface. This controls whether packets |
|
received _on_ this interface can be forwarded. |
|
|
|
mc_forwarding - BOOLEAN |
|
Do multicast routing. The kernel needs to be compiled with CONFIG_MROUTE |
|
and a multicast routing daemon is required. |
|
conf/all/mc_forwarding must also be set to TRUE to enable multicast |
|
routing for the interface |
|
|
|
medium_id - INTEGER |
|
Integer value used to differentiate the devices by the medium they |
|
are attached to. Two devices can have different id values when |
|
the broadcast packets are received only on one of them. |
|
The default value 0 means that the device is the only interface |
|
to its medium, value of -1 means that medium is not known. |
|
|
|
Currently, it is used to change the proxy_arp behavior: |
|
the proxy_arp feature is enabled for packets forwarded between |
|
two devices attached to different media. |
|
|
|
proxy_arp - BOOLEAN |
|
Do proxy arp. |
|
|
|
proxy_arp for the interface will be enabled if at least one of |
|
conf/{all,interface}/proxy_arp is set to TRUE, |
|
it will be disabled otherwise |
|
|
|
proxy_arp_pvlan - BOOLEAN |
|
Private VLAN proxy arp. |
|
|
|
Basically allow proxy arp replies back to the same interface |
|
(from which the ARP request/solicitation was received). |
|
|
|
This is done to support (ethernet) switch features, like RFC |
|
3069, where the individual ports are NOT allowed to |
|
communicate with each other, but they are allowed to talk to |
|
the upstream router. As described in RFC 3069, it is possible |
|
to allow these hosts to communicate through the upstream |
|
router by proxy_arp'ing. Don't need to be used together with |
|
proxy_arp. |
|
|
|
This technology is known by different names: |
|
|
|
In RFC 3069 it is called VLAN Aggregation. |
|
Cisco and Allied Telesyn call it Private VLAN. |
|
Hewlett-Packard call it Source-Port filtering or port-isolation. |
|
Ericsson call it MAC-Forced Forwarding (RFC Draft). |
|
|
|
shared_media - BOOLEAN |
|
Send(router) or accept(host) RFC1620 shared media redirects. |
|
Overrides secure_redirects. |
|
|
|
shared_media for the interface will be enabled if at least one of |
|
conf/{all,interface}/shared_media is set to TRUE, |
|
it will be disabled otherwise |
|
|
|
default TRUE |
|
|
|
secure_redirects - BOOLEAN |
|
Accept ICMP redirect messages only to gateways listed in the |
|
interface's current gateway list. Even if disabled, RFC1122 redirect |
|
rules still apply. |
|
|
|
Overridden by shared_media. |
|
|
|
secure_redirects for the interface will be enabled if at least one of |
|
conf/{all,interface}/secure_redirects is set to TRUE, |
|
it will be disabled otherwise |
|
|
|
default TRUE |
|
|
|
send_redirects - BOOLEAN |
|
Send redirects, if router. |
|
|
|
send_redirects for the interface will be enabled if at least one of |
|
conf/{all,interface}/send_redirects is set to TRUE, |
|
it will be disabled otherwise |
|
|
|
Default: TRUE |
|
|
|
bootp_relay - BOOLEAN |
|
Accept packets with source address 0.b.c.d destined |
|
not to this host as local ones. It is supposed, that |
|
BOOTP relay daemon will catch and forward such packets. |
|
conf/all/bootp_relay must also be set to TRUE to enable BOOTP relay |
|
for the interface |
|
|
|
default FALSE |
|
|
|
Not Implemented Yet. |
|
|
|
accept_source_route - BOOLEAN |
|
Accept packets with SRR option. |
|
conf/all/accept_source_route must also be set to TRUE to accept packets |
|
with SRR option on the interface |
|
|
|
default |
|
|
|
- TRUE (router) |
|
- FALSE (host) |
|
|
|
accept_local - BOOLEAN |
|
Accept packets with local source addresses. In combination with |
|
suitable routing, this can be used to direct packets between two |
|
local interfaces over the wire and have them accepted properly. |
|
default FALSE |
|
|
|
route_localnet - BOOLEAN |
|
Do not consider loopback addresses as martian source or destination |
|
while routing. This enables the use of 127/8 for local routing purposes. |
|
|
|
default FALSE |
|
|
|
rp_filter - INTEGER |
|
- 0 - No source validation. |
|
- 1 - Strict mode as defined in RFC3704 Strict Reverse Path |
|
Each incoming packet is tested against the FIB and if the interface |
|
is not the best reverse path the packet check will fail. |
|
By default failed packets are discarded. |
|
- 2 - Loose mode as defined in RFC3704 Loose Reverse Path |
|
Each incoming packet's source address is also tested against the FIB |
|
and if the source address is not reachable via any interface |
|
the packet check will fail. |
|
|
|
Current recommended practice in RFC3704 is to enable strict mode |
|
to prevent IP spoofing from DDos attacks. If using asymmetric routing |
|
or other complicated routing, then loose mode is recommended. |
|
|
|
The max value from conf/{all,interface}/rp_filter is used |
|
when doing source validation on the {interface}. |
|
|
|
Default value is 0. Note that some distributions enable it |
|
in startup scripts. |
|
|
|
src_valid_mark - BOOLEAN |
|
- 0 - The fwmark of the packet is not included in reverse path |
|
route lookup. This allows for asymmetric routing configurations |
|
utilizing the fwmark in only one direction, e.g., transparent |
|
proxying. |
|
|
|
- 1 - The fwmark of the packet is included in reverse path route |
|
lookup. This permits rp_filter to function when the fwmark is |
|
used for routing traffic in both directions. |
|
|
|
This setting also affects the utilization of fmwark when |
|
performing source address selection for ICMP replies, or |
|
determining addresses stored for the IPOPT_TS_TSANDADDR and |
|
IPOPT_RR IP options. |
|
|
|
The max value from conf/{all,interface}/src_valid_mark is used. |
|
|
|
Default value is 0. |
|
|
|
arp_filter - BOOLEAN |
|
- 1 - Allows you to have multiple network interfaces on the same |
|
subnet, and have the ARPs for each interface be answered |
|
based on whether or not the kernel would route a packet from |
|
the ARP'd IP out that interface (therefore you must use source |
|
based routing for this to work). In other words it allows control |
|
of which cards (usually 1) will respond to an arp request. |
|
|
|
- 0 - (default) The kernel can respond to arp requests with addresses |
|
from other interfaces. This may seem wrong but it usually makes |
|
sense, because it increases the chance of successful communication. |
|
IP addresses are owned by the complete host on Linux, not by |
|
particular interfaces. Only for more complex setups like load- |
|
balancing, does this behaviour cause problems. |
|
|
|
arp_filter for the interface will be enabled if at least one of |
|
conf/{all,interface}/arp_filter is set to TRUE, |
|
it will be disabled otherwise |
|
|
|
arp_announce - INTEGER |
|
Define different restriction levels for announcing the local |
|
source IP address from IP packets in ARP requests sent on |
|
interface: |
|
|
|
- 0 - (default) Use any local address, configured on any interface |
|
- 1 - Try to avoid local addresses that are not in the target's |
|
subnet for this interface. This mode is useful when target |
|
hosts reachable via this interface require the source IP |
|
address in ARP requests to be part of their logical network |
|
configured on the receiving interface. When we generate the |
|
request we will check all our subnets that include the |
|
target IP and will preserve the source address if it is from |
|
such subnet. If there is no such subnet we select source |
|
address according to the rules for level 2. |
|
- 2 - Always use the best local address for this target. |
|
In this mode we ignore the source address in the IP packet |
|
and try to select local address that we prefer for talks with |
|
the target host. Such local address is selected by looking |
|
for primary IP addresses on all our subnets on the outgoing |
|
interface that include the target IP address. If no suitable |
|
local address is found we select the first local address |
|
we have on the outgoing interface or on all other interfaces, |
|
with the hope we will receive reply for our request and |
|
even sometimes no matter the source IP address we announce. |
|
|
|
The max value from conf/{all,interface}/arp_announce is used. |
|
|
|
Increasing the restriction level gives more chance for |
|
receiving answer from the resolved target while decreasing |
|
the level announces more valid sender's information. |
|
|
|
arp_ignore - INTEGER |
|
Define different modes for sending replies in response to |
|
received ARP requests that resolve local target IP addresses: |
|
|
|
- 0 - (default): reply for any local target IP address, configured |
|
on any interface |
|
- 1 - reply only if the target IP address is local address |
|
configured on the incoming interface |
|
- 2 - reply only if the target IP address is local address |
|
configured on the incoming interface and both with the |
|
sender's IP address are part from same subnet on this interface |
|
- 3 - do not reply for local addresses configured with scope host, |
|
only resolutions for global and link addresses are replied |
|
- 4-7 - reserved |
|
- 8 - do not reply for all local addresses |
|
|
|
The max value from conf/{all,interface}/arp_ignore is used |
|
when ARP request is received on the {interface} |
|
|
|
arp_notify - BOOLEAN |
|
Define mode for notification of address and device changes. |
|
|
|
== ========================================================== |
|
0 (default): do nothing |
|
1 Generate gratuitous arp requests when device is brought up |
|
or hardware address changes. |
|
== ========================================================== |
|
|
|
arp_accept - BOOLEAN |
|
Define behavior for gratuitous ARP frames who's IP is not |
|
already present in the ARP table: |
|
|
|
- 0 - don't create new entries in the ARP table |
|
- 1 - create new entries in the ARP table |
|
|
|
Both replies and requests type gratuitous arp will trigger the |
|
ARP table to be updated, if this setting is on. |
|
|
|
If the ARP table already contains the IP address of the |
|
gratuitous arp frame, the arp table will be updated regardless |
|
if this setting is on or off. |
|
|
|
mcast_solicit - INTEGER |
|
The maximum number of multicast probes in INCOMPLETE state, |
|
when the associated hardware address is unknown. Defaults |
|
to 3. |
|
|
|
ucast_solicit - INTEGER |
|
The maximum number of unicast probes in PROBE state, when |
|
the hardware address is being reconfirmed. Defaults to 3. |
|
|
|
app_solicit - INTEGER |
|
The maximum number of probes to send to the user space ARP daemon |
|
via netlink before dropping back to multicast probes (see |
|
mcast_resolicit). Defaults to 0. |
|
|
|
mcast_resolicit - INTEGER |
|
The maximum number of multicast probes after unicast and |
|
app probes in PROBE state. Defaults to 0. |
|
|
|
disable_policy - BOOLEAN |
|
Disable IPSEC policy (SPD) for this interface |
|
|
|
disable_xfrm - BOOLEAN |
|
Disable IPSEC encryption on this interface, whatever the policy |
|
|
|
igmpv2_unsolicited_report_interval - INTEGER |
|
The interval in milliseconds in which the next unsolicited |
|
IGMPv1 or IGMPv2 report retransmit will take place. |
|
|
|
Default: 10000 (10 seconds) |
|
|
|
igmpv3_unsolicited_report_interval - INTEGER |
|
The interval in milliseconds in which the next unsolicited |
|
IGMPv3 report retransmit will take place. |
|
|
|
Default: 1000 (1 seconds) |
|
|
|
ignore_routes_with_linkdown - BOOLEAN |
|
Ignore routes whose link is down when performing a FIB lookup. |
|
|
|
promote_secondaries - BOOLEAN |
|
When a primary IP address is removed from this interface |
|
promote a corresponding secondary IP address instead of |
|
removing all the corresponding secondary IP addresses. |
|
|
|
drop_unicast_in_l2_multicast - BOOLEAN |
|
Drop any unicast IP packets that are received in link-layer |
|
multicast (or broadcast) frames. |
|
|
|
This behavior (for multicast) is actually a SHOULD in RFC |
|
1122, but is disabled by default for compatibility reasons. |
|
|
|
Default: off (0) |
|
|
|
drop_gratuitous_arp - BOOLEAN |
|
Drop all gratuitous ARP frames, for example if there's a known |
|
good ARP proxy on the network and such frames need not be used |
|
(or in the case of 802.11, must not be used to prevent attacks.) |
|
|
|
Default: off (0) |
|
|
|
|
|
tag - INTEGER |
|
Allows you to write a number, which can be used as required. |
|
|
|
Default value is 0. |
|
|
|
xfrm4_gc_thresh - INTEGER |
|
(Obsolete since linux-4.14) |
|
The threshold at which we will start garbage collecting for IPv4 |
|
destination cache entries. At twice this value the system will |
|
refuse new allocations. |
|
|
|
igmp_link_local_mcast_reports - BOOLEAN |
|
Enable IGMP reports for link local multicast groups in the |
|
224.0.0.X range. |
|
|
|
Default TRUE |
|
|
|
Alexey Kuznetsov. |
|
[email protected] |
|
|
|
Updated by: |
|
|
|
- Andi Kleen |
|
[email protected] |
|
- Nicolas Delon |
|
[email protected] |
|
|
|
|
|
|
|
|
|
/proc/sys/net/ipv6/* Variables |
|
============================== |
|
|
|
IPv6 has no global variables such as tcp_*. tcp_* settings under ipv4/ also |
|
apply to IPv6 [XXX?]. |
|
|
|
bindv6only - BOOLEAN |
|
Default value for IPV6_V6ONLY socket option, |
|
which restricts use of the IPv6 socket to IPv6 communication |
|
only. |
|
|
|
- TRUE: disable IPv4-mapped address feature |
|
- FALSE: enable IPv4-mapped address feature |
|
|
|
Default: FALSE (as specified in RFC3493) |
|
|
|
flowlabel_consistency - BOOLEAN |
|
Protect the consistency (and unicity) of flow label. |
|
You have to disable it to use IPV6_FL_F_REFLECT flag on the |
|
flow label manager. |
|
|
|
- TRUE: enabled |
|
- FALSE: disabled |
|
|
|
Default: TRUE |
|
|
|
auto_flowlabels - INTEGER |
|
Automatically generate flow labels based on a flow hash of the |
|
packet. This allows intermediate devices, such as routers, to |
|
identify packet flows for mechanisms like Equal Cost Multipath |
|
Routing (see RFC 6438). |
|
|
|
= =========================================================== |
|
0 automatic flow labels are completely disabled |
|
1 automatic flow labels are enabled by default, they can be |
|
disabled on a per socket basis using the IPV6_AUTOFLOWLABEL |
|
socket option |
|
2 automatic flow labels are allowed, they may be enabled on a |
|
per socket basis using the IPV6_AUTOFLOWLABEL socket option |
|
3 automatic flow labels are enabled and enforced, they cannot |
|
be disabled by the socket option |
|
= =========================================================== |
|
|
|
Default: 1 |
|
|
|
flowlabel_state_ranges - BOOLEAN |
|
Split the flow label number space into two ranges. 0-0x7FFFF is |
|
reserved for the IPv6 flow manager facility, 0x80000-0xFFFFF |
|
is reserved for stateless flow labels as described in RFC6437. |
|
|
|
- TRUE: enabled |
|
- FALSE: disabled |
|
|
|
Default: true |
|
|
|
flowlabel_reflect - INTEGER |
|
Control flow label reflection. Needed for Path MTU |
|
Discovery to work with Equal Cost Multipath Routing in anycast |
|
environments. See RFC 7690 and: |
|
https://tools.ietf.org/html/draft-wang-6man-flow-label-reflection-01 |
|
|
|
This is a bitmask. |
|
|
|
- 1: enabled for established flows |
|
|
|
Note that this prevents automatic flowlabel changes, as done |
|
in "tcp: change IPv6 flow-label upon receiving spurious retransmission" |
|
and "tcp: Change txhash on every SYN and RTO retransmit" |
|
|
|
- 2: enabled for TCP RESET packets (no active listener) |
|
If set, a RST packet sent in response to a SYN packet on a closed |
|
port will reflect the incoming flow label. |
|
|
|
- 4: enabled for ICMPv6 echo reply messages. |
|
|
|
Default: 0 |
|
|
|
fib_multipath_hash_policy - INTEGER |
|
Controls which hash policy to use for multipath routes. |
|
|
|
Default: 0 (Layer 3) |
|
|
|
Possible values: |
|
|
|
- 0 - Layer 3 (source and destination addresses plus flow label) |
|
- 1 - Layer 4 (standard 5-tuple) |
|
- 2 - Layer 3 or inner Layer 3 if present |
|
|
|
anycast_src_echo_reply - BOOLEAN |
|
Controls the use of anycast addresses as source addresses for ICMPv6 |
|
echo reply |
|
|
|
- TRUE: enabled |
|
- FALSE: disabled |
|
|
|
Default: FALSE |
|
|
|
idgen_delay - INTEGER |
|
Controls the delay in seconds after which time to retry |
|
privacy stable address generation if a DAD conflict is |
|
detected. |
|
|
|
Default: 1 (as specified in RFC7217) |
|
|
|
idgen_retries - INTEGER |
|
Controls the number of retries to generate a stable privacy |
|
address if a DAD conflict is detected. |
|
|
|
Default: 3 (as specified in RFC7217) |
|
|
|
mld_qrv - INTEGER |
|
Controls the MLD query robustness variable (see RFC3810 9.1). |
|
|
|
Default: 2 (as specified by RFC3810 9.1) |
|
|
|
Minimum: 1 (as specified by RFC6636 4.5) |
|
|
|
max_dst_opts_number - INTEGER |
|
Maximum number of non-padding TLVs allowed in a Destination |
|
options extension header. If this value is less than zero |
|
then unknown options are disallowed and the number of known |
|
TLVs allowed is the absolute value of this number. |
|
|
|
Default: 8 |
|
|
|
max_hbh_opts_number - INTEGER |
|
Maximum number of non-padding TLVs allowed in a Hop-by-Hop |
|
options extension header. If this value is less than zero |
|
then unknown options are disallowed and the number of known |
|
TLVs allowed is the absolute value of this number. |
|
|
|
Default: 8 |
|
|
|
max_dst_opts_length - INTEGER |
|
Maximum length allowed for a Destination options extension |
|
header. |
|
|
|
Default: INT_MAX (unlimited) |
|
|
|
max_hbh_length - INTEGER |
|
Maximum length allowed for a Hop-by-Hop options extension |
|
header. |
|
|
|
Default: INT_MAX (unlimited) |
|
|
|
skip_notify_on_dev_down - BOOLEAN |
|
Controls whether an RTM_DELROUTE message is generated for routes |
|
removed when a device is taken down or deleted. IPv4 does not |
|
generate this message; IPv6 does by default. Setting this sysctl |
|
to true skips the message, making IPv4 and IPv6 on par in relying |
|
on userspace caches to track link events and evict routes. |
|
|
|
Default: false (generate message) |
|
|
|
nexthop_compat_mode - BOOLEAN |
|
New nexthop API provides a means for managing nexthops independent of |
|
prefixes. Backwards compatibilty with old route format is enabled by |
|
default which means route dumps and notifications contain the new |
|
nexthop attribute but also the full, expanded nexthop definition. |
|
Further, updates or deletes of a nexthop configuration generate route |
|
notifications for each fib entry using the nexthop. Once a system |
|
understands the new API, this sysctl can be disabled to achieve full |
|
performance benefits of the new API by disabling the nexthop expansion |
|
and extraneous notifications. |
|
Default: true (backward compat mode) |
|
|
|
fib_notify_on_flag_change - INTEGER |
|
Whether to emit RTM_NEWROUTE notifications whenever RTM_F_OFFLOAD/ |
|
RTM_F_TRAP/RTM_F_OFFLOAD_FAILED flags are changed. |
|
|
|
After installing a route to the kernel, user space receives an |
|
acknowledgment, which means the route was installed in the kernel, |
|
but not necessarily in hardware. |
|
It is also possible for a route already installed in hardware to change |
|
its action and therefore its flags. For example, a host route that is |
|
trapping packets can be "promoted" to perform decapsulation following |
|
the installation of an IPinIP/VXLAN tunnel. |
|
The notifications will indicate to user-space the state of the route. |
|
|
|
Default: 0 (Do not emit notifications.) |
|
|
|
Possible values: |
|
|
|
- 0 - Do not emit notifications. |
|
- 1 - Emit notifications. |
|
- 2 - Emit notifications only for RTM_F_OFFLOAD_FAILED flag change. |
|
|
|
IPv6 Fragmentation: |
|
|
|
ip6frag_high_thresh - INTEGER |
|
Maximum memory used to reassemble IPv6 fragments. When |
|
ip6frag_high_thresh bytes of memory is allocated for this purpose, |
|
the fragment handler will toss packets until ip6frag_low_thresh |
|
is reached. |
|
|
|
ip6frag_low_thresh - INTEGER |
|
See ip6frag_high_thresh |
|
|
|
ip6frag_time - INTEGER |
|
Time in seconds to keep an IPv6 fragment in memory. |
|
|
|
``conf/default/*``: |
|
Change the interface-specific default settings. |
|
|
|
These settings would be used during creating new interfaces. |
|
|
|
|
|
``conf/all/*``: |
|
Change all the interface-specific settings. |
|
|
|
[XXX: Other special features than forwarding?] |
|
|
|
conf/all/disable_ipv6 - BOOLEAN |
|
Changing this value is same as changing ``conf/default/disable_ipv6`` |
|
setting and also all per-interface ``disable_ipv6`` settings to the same |
|
value. |
|
|
|
Reading this value does not have any particular meaning. It does not say |
|
whether IPv6 support is enabled or disabled. Returned value can be 1 |
|
also in the case when some interface has ``disable_ipv6`` set to 0 and |
|
has configured IPv6 addresses. |
|
|
|
conf/all/forwarding - BOOLEAN |
|
Enable global IPv6 forwarding between all interfaces. |
|
|
|
IPv4 and IPv6 work differently here; e.g. netfilter must be used |
|
to control which interfaces may forward packets and which not. |
|
|
|
This also sets all interfaces' Host/Router setting |
|
'forwarding' to the specified value. See below for details. |
|
|
|
This referred to as global forwarding. |
|
|
|
proxy_ndp - BOOLEAN |
|
Do proxy ndp. |
|
|
|
fwmark_reflect - BOOLEAN |
|
Controls the fwmark of kernel-generated IPv6 reply packets that are not |
|
associated with a socket for example, TCP RSTs or ICMPv6 echo replies). |
|
If unset, these packets have a fwmark of zero. If set, they have the |
|
fwmark of the packet they are replying to. |
|
|
|
Default: 0 |
|
|
|
``conf/interface/*``: |
|
Change special settings per interface. |
|
|
|
The functional behaviour for certain settings is different |
|
depending on whether local forwarding is enabled or not. |
|
|
|
accept_ra - INTEGER |
|
Accept Router Advertisements; autoconfigure using them. |
|
|
|
It also determines whether or not to transmit Router |
|
Solicitations. If and only if the functional setting is to |
|
accept Router Advertisements, Router Solicitations will be |
|
transmitted. |
|
|
|
Possible values are: |
|
|
|
== =========================================================== |
|
0 Do not accept Router Advertisements. |
|
1 Accept Router Advertisements if forwarding is disabled. |
|
2 Overrule forwarding behaviour. Accept Router Advertisements |
|
even if forwarding is enabled. |
|
== =========================================================== |
|
|
|
Functional default: |
|
|
|
- enabled if local forwarding is disabled. |
|
- disabled if local forwarding is enabled. |
|
|
|
accept_ra_defrtr - BOOLEAN |
|
Learn default router in Router Advertisement. |
|
|
|
Functional default: |
|
|
|
- enabled if accept_ra is enabled. |
|
- disabled if accept_ra is disabled. |
|
|
|
ra_defrtr_metric - UNSIGNED INTEGER |
|
Route metric for default route learned in Router Advertisement. This value |
|
will be assigned as metric for the default route learned via IPv6 Router |
|
Advertisement. Takes affect only if accept_ra_defrtr is enabled. |
|
|
|
Possible values: |
|
1 to 0xFFFFFFFF |
|
|
|
Default: IP6_RT_PRIO_USER i.e. 1024. |
|
|
|
accept_ra_from_local - BOOLEAN |
|
Accept RA with source-address that is found on local machine |
|
if the RA is otherwise proper and able to be accepted. |
|
|
|
Default is to NOT accept these as it may be an un-intended |
|
network loop. |
|
|
|
Functional default: |
|
|
|
- enabled if accept_ra_from_local is enabled |
|
on a specific interface. |
|
- disabled if accept_ra_from_local is disabled |
|
on a specific interface. |
|
|
|
accept_ra_min_hop_limit - INTEGER |
|
Minimum hop limit Information in Router Advertisement. |
|
|
|
Hop limit Information in Router Advertisement less than this |
|
variable shall be ignored. |
|
|
|
Default: 1 |
|
|
|
accept_ra_pinfo - BOOLEAN |
|
Learn Prefix Information in Router Advertisement. |
|
|
|
Functional default: |
|
|
|
- enabled if accept_ra is enabled. |
|
- disabled if accept_ra is disabled. |
|
|
|
accept_ra_rt_info_min_plen - INTEGER |
|
Minimum prefix length of Route Information in RA. |
|
|
|
Route Information w/ prefix smaller than this variable shall |
|
be ignored. |
|
|
|
Functional default: |
|
|
|
* 0 if accept_ra_rtr_pref is enabled. |
|
* -1 if accept_ra_rtr_pref is disabled. |
|
|
|
accept_ra_rt_info_max_plen - INTEGER |
|
Maximum prefix length of Route Information in RA. |
|
|
|
Route Information w/ prefix larger than this variable shall |
|
be ignored. |
|
|
|
Functional default: |
|
|
|
* 0 if accept_ra_rtr_pref is enabled. |
|
* -1 if accept_ra_rtr_pref is disabled. |
|
|
|
accept_ra_rtr_pref - BOOLEAN |
|
Accept Router Preference in RA. |
|
|
|
Functional default: |
|
|
|
- enabled if accept_ra is enabled. |
|
- disabled if accept_ra is disabled. |
|
|
|
accept_ra_mtu - BOOLEAN |
|
Apply the MTU value specified in RA option 5 (RFC4861). If |
|
disabled, the MTU specified in the RA will be ignored. |
|
|
|
Functional default: |
|
|
|
- enabled if accept_ra is enabled. |
|
- disabled if accept_ra is disabled. |
|
|
|
accept_redirects - BOOLEAN |
|
Accept Redirects. |
|
|
|
Functional default: |
|
|
|
- enabled if local forwarding is disabled. |
|
- disabled if local forwarding is enabled. |
|
|
|
accept_source_route - INTEGER |
|
Accept source routing (routing extension header). |
|
|
|
- >= 0: Accept only routing header type 2. |
|
- < 0: Do not accept routing header. |
|
|
|
Default: 0 |
|
|
|
autoconf - BOOLEAN |
|
Autoconfigure addresses using Prefix Information in Router |
|
Advertisements. |
|
|
|
Functional default: |
|
|
|
- enabled if accept_ra_pinfo is enabled. |
|
- disabled if accept_ra_pinfo is disabled. |
|
|
|
dad_transmits - INTEGER |
|
The amount of Duplicate Address Detection probes to send. |
|
|
|
Default: 1 |
|
|
|
forwarding - INTEGER |
|
Configure interface-specific Host/Router behaviour. |
|
|
|
.. note:: |
|
|
|
It is recommended to have the same setting on all |
|
interfaces; mixed router/host scenarios are rather uncommon. |
|
|
|
Possible values are: |
|
|
|
- 0 Forwarding disabled |
|
- 1 Forwarding enabled |
|
|
|
**FALSE (0)**: |
|
|
|
By default, Host behaviour is assumed. This means: |
|
|
|
1. IsRouter flag is not set in Neighbour Advertisements. |
|
2. If accept_ra is TRUE (default), transmit Router |
|
Solicitations. |
|
3. If accept_ra is TRUE (default), accept Router |
|
Advertisements (and do autoconfiguration). |
|
4. If accept_redirects is TRUE (default), accept Redirects. |
|
|
|
**TRUE (1)**: |
|
|
|
If local forwarding is enabled, Router behaviour is assumed. |
|
This means exactly the reverse from the above: |
|
|
|
1. IsRouter flag is set in Neighbour Advertisements. |
|
2. Router Solicitations are not sent unless accept_ra is 2. |
|
3. Router Advertisements are ignored unless accept_ra is 2. |
|
4. Redirects are ignored. |
|
|
|
Default: 0 (disabled) if global forwarding is disabled (default), |
|
otherwise 1 (enabled). |
|
|
|
hop_limit - INTEGER |
|
Default Hop Limit to set. |
|
|
|
Default: 64 |
|
|
|
mtu - INTEGER |
|
Default Maximum Transfer Unit |
|
|
|
Default: 1280 (IPv6 required minimum) |
|
|
|
ip_nonlocal_bind - BOOLEAN |
|
If set, allows processes to bind() to non-local IPv6 addresses, |
|
which can be quite useful - but may break some applications. |
|
|
|
Default: 0 |
|
|
|
router_probe_interval - INTEGER |
|
Minimum interval (in seconds) between Router Probing described |
|
in RFC4191. |
|
|
|
Default: 60 |
|
|
|
router_solicitation_delay - INTEGER |
|
Number of seconds to wait after interface is brought up |
|
before sending Router Solicitations. |
|
|
|
Default: 1 |
|
|
|
router_solicitation_interval - INTEGER |
|
Number of seconds to wait between Router Solicitations. |
|
|
|
Default: 4 |
|
|
|
router_solicitations - INTEGER |
|
Number of Router Solicitations to send until assuming no |
|
routers are present. |
|
|
|
Default: 3 |
|
|
|
use_oif_addrs_only - BOOLEAN |
|
When enabled, the candidate source addresses for destinations |
|
routed via this interface are restricted to the set of addresses |
|
configured on this interface (vis. RFC 6724, section 4). |
|
|
|
Default: false |
|
|
|
use_tempaddr - INTEGER |
|
Preference for Privacy Extensions (RFC3041). |
|
|
|
* <= 0 : disable Privacy Extensions |
|
* == 1 : enable Privacy Extensions, but prefer public |
|
addresses over temporary addresses. |
|
* > 1 : enable Privacy Extensions and prefer temporary |
|
addresses over public addresses. |
|
|
|
Default: |
|
|
|
* 0 (for most devices) |
|
* -1 (for point-to-point devices and loopback devices) |
|
|
|
temp_valid_lft - INTEGER |
|
valid lifetime (in seconds) for temporary addresses. |
|
|
|
Default: 172800 (2 days) |
|
|
|
temp_prefered_lft - INTEGER |
|
Preferred lifetime (in seconds) for temporary addresses. |
|
|
|
Default: 86400 (1 day) |
|
|
|
keep_addr_on_down - INTEGER |
|
Keep all IPv6 addresses on an interface down event. If set static |
|
global addresses with no expiration time are not flushed. |
|
|
|
* >0 : enabled |
|
* 0 : system default |
|
* <0 : disabled |
|
|
|
Default: 0 (addresses are removed) |
|
|
|
max_desync_factor - INTEGER |
|
Maximum value for DESYNC_FACTOR, which is a random value |
|
that ensures that clients don't synchronize with each |
|
other and generate new addresses at exactly the same time. |
|
value is in seconds. |
|
|
|
Default: 600 |
|
|
|
regen_max_retry - INTEGER |
|
Number of attempts before give up attempting to generate |
|
valid temporary addresses. |
|
|
|
Default: 5 |
|
|
|
max_addresses - INTEGER |
|
Maximum number of autoconfigured addresses per interface. Setting |
|
to zero disables the limitation. It is not recommended to set this |
|
value too large (or to zero) because it would be an easy way to |
|
crash the kernel by allowing too many addresses to be created. |
|
|
|
Default: 16 |
|
|
|
disable_ipv6 - BOOLEAN |
|
Disable IPv6 operation. If accept_dad is set to 2, this value |
|
will be dynamically set to TRUE if DAD fails for the link-local |
|
address. |
|
|
|
Default: FALSE (enable IPv6 operation) |
|
|
|
When this value is changed from 1 to 0 (IPv6 is being enabled), |
|
it will dynamically create a link-local address on the given |
|
interface and start Duplicate Address Detection, if necessary. |
|
|
|
When this value is changed from 0 to 1 (IPv6 is being disabled), |
|
it will dynamically delete all addresses and routes on the given |
|
interface. From now on it will not possible to add addresses/routes |
|
to the selected interface. |
|
|
|
accept_dad - INTEGER |
|
Whether to accept DAD (Duplicate Address Detection). |
|
|
|
== ============================================================== |
|
0 Disable DAD |
|
1 Enable DAD (default) |
|
2 Enable DAD, and disable IPv6 operation if MAC-based duplicate |
|
link-local address has been found. |
|
== ============================================================== |
|
|
|
DAD operation and mode on a given interface will be selected according |
|
to the maximum value of conf/{all,interface}/accept_dad. |
|
|
|
force_tllao - BOOLEAN |
|
Enable sending the target link-layer address option even when |
|
responding to a unicast neighbor solicitation. |
|
|
|
Default: FALSE |
|
|
|
Quoting from RFC 2461, section 4.4, Target link-layer address: |
|
|
|
"The option MUST be included for multicast solicitations in order to |
|
avoid infinite Neighbor Solicitation "recursion" when the peer node |
|
does not have a cache entry to return a Neighbor Advertisements |
|
message. When responding to unicast solicitations, the option can be |
|
omitted since the sender of the solicitation has the correct link- |
|
layer address; otherwise it would not have be able to send the unicast |
|
solicitation in the first place. However, including the link-layer |
|
address in this case adds little overhead and eliminates a potential |
|
race condition where the sender deletes the cached link-layer address |
|
prior to receiving a response to a previous solicitation." |
|
|
|
ndisc_notify - BOOLEAN |
|
Define mode for notification of address and device changes. |
|
|
|
* 0 - (default): do nothing |
|
* 1 - Generate unsolicited neighbour advertisements when device is brought |
|
up or hardware address changes. |
|
|
|
ndisc_tclass - INTEGER |
|
The IPv6 Traffic Class to use by default when sending IPv6 Neighbor |
|
Discovery (Router Solicitation, Router Advertisement, Neighbor |
|
Solicitation, Neighbor Advertisement, Redirect) messages. |
|
These 8 bits can be interpreted as 6 high order bits holding the DSCP |
|
value and 2 low order bits representing ECN (which you probably want |
|
to leave cleared). |
|
|
|
* 0 - (default) |
|
|
|
mldv1_unsolicited_report_interval - INTEGER |
|
The interval in milliseconds in which the next unsolicited |
|
MLDv1 report retransmit will take place. |
|
|
|
Default: 10000 (10 seconds) |
|
|
|
mldv2_unsolicited_report_interval - INTEGER |
|
The interval in milliseconds in which the next unsolicited |
|
MLDv2 report retransmit will take place. |
|
|
|
Default: 1000 (1 second) |
|
|
|
force_mld_version - INTEGER |
|
* 0 - (default) No enforcement of a MLD version, MLDv1 fallback allowed |
|
* 1 - Enforce to use MLD version 1 |
|
* 2 - Enforce to use MLD version 2 |
|
|
|
suppress_frag_ndisc - INTEGER |
|
Control RFC 6980 (Security Implications of IPv6 Fragmentation |
|
with IPv6 Neighbor Discovery) behavior: |
|
|
|
* 1 - (default) discard fragmented neighbor discovery packets |
|
* 0 - allow fragmented neighbor discovery packets |
|
|
|
optimistic_dad - BOOLEAN |
|
Whether to perform Optimistic Duplicate Address Detection (RFC 4429). |
|
|
|
* 0: disabled (default) |
|
* 1: enabled |
|
|
|
Optimistic Duplicate Address Detection for the interface will be enabled |
|
if at least one of conf/{all,interface}/optimistic_dad is set to 1, |
|
it will be disabled otherwise. |
|
|
|
use_optimistic - BOOLEAN |
|
If enabled, do not classify optimistic addresses as deprecated during |
|
source address selection. Preferred addresses will still be chosen |
|
before optimistic addresses, subject to other ranking in the source |
|
address selection algorithm. |
|
|
|
* 0: disabled (default) |
|
* 1: enabled |
|
|
|
This will be enabled if at least one of |
|
conf/{all,interface}/use_optimistic is set to 1, disabled otherwise. |
|
|
|
stable_secret - IPv6 address |
|
This IPv6 address will be used as a secret to generate IPv6 |
|
addresses for link-local addresses and autoconfigured |
|
ones. All addresses generated after setting this secret will |
|
be stable privacy ones by default. This can be changed via the |
|
addrgenmode ip-link. conf/default/stable_secret is used as the |
|
secret for the namespace, the interface specific ones can |
|
overwrite that. Writes to conf/all/stable_secret are refused. |
|
|
|
It is recommended to generate this secret during installation |
|
of a system and keep it stable after that. |
|
|
|
By default the stable secret is unset. |
|
|
|
addr_gen_mode - INTEGER |
|
Defines how link-local and autoconf addresses are generated. |
|
|
|
= ================================================================= |
|
0 generate address based on EUI64 (default) |
|
1 do no generate a link-local address, use EUI64 for addresses |
|
generated from autoconf |
|
2 generate stable privacy addresses, using the secret from |
|
stable_secret (RFC7217) |
|
3 generate stable privacy addresses, using a random secret if unset |
|
= ================================================================= |
|
|
|
drop_unicast_in_l2_multicast - BOOLEAN |
|
Drop any unicast IPv6 packets that are received in link-layer |
|
multicast (or broadcast) frames. |
|
|
|
By default this is turned off. |
|
|
|
drop_unsolicited_na - BOOLEAN |
|
Drop all unsolicited neighbor advertisements, for example if there's |
|
a known good NA proxy on the network and such frames need not be used |
|
(or in the case of 802.11, must not be used to prevent attacks.) |
|
|
|
By default this is turned off. |
|
|
|
enhanced_dad - BOOLEAN |
|
Include a nonce option in the IPv6 neighbor solicitation messages used for |
|
duplicate address detection per RFC7527. A received DAD NS will only signal |
|
a duplicate address if the nonce is different. This avoids any false |
|
detection of duplicates due to loopback of the NS messages that we send. |
|
The nonce option will be sent on an interface unless both of |
|
conf/{all,interface}/enhanced_dad are set to FALSE. |
|
|
|
Default: TRUE |
|
|
|
``icmp/*``: |
|
=========== |
|
|
|
ratelimit - INTEGER |
|
Limit the maximal rates for sending ICMPv6 messages. |
|
|
|
0 to disable any limiting, |
|
otherwise the minimal space between responses in milliseconds. |
|
|
|
Default: 1000 |
|
|
|
ratemask - list of comma separated ranges |
|
For ICMPv6 message types matching the ranges in the ratemask, limit |
|
the sending of the message according to ratelimit parameter. |
|
|
|
The format used for both input and output is a comma separated |
|
list of ranges (e.g. "0-127,129" for ICMPv6 message type 0 to 127 and |
|
129). Writing to the file will clear all previous ranges of ICMPv6 |
|
message types and update the current list with the input. |
|
|
|
Refer to: https://www.iana.org/assignments/icmpv6-parameters/icmpv6-parameters.xhtml |
|
for numerical values of ICMPv6 message types, e.g. echo request is 128 |
|
and echo reply is 129. |
|
|
|
Default: 0-1,3-127 (rate limit ICMPv6 errors except Packet Too Big) |
|
|
|
echo_ignore_all - BOOLEAN |
|
If set non-zero, then the kernel will ignore all ICMP ECHO |
|
requests sent to it over the IPv6 protocol. |
|
|
|
Default: 0 |
|
|
|
echo_ignore_multicast - BOOLEAN |
|
If set non-zero, then the kernel will ignore all ICMP ECHO |
|
requests sent to it over the IPv6 protocol via multicast. |
|
|
|
Default: 0 |
|
|
|
echo_ignore_anycast - BOOLEAN |
|
If set non-zero, then the kernel will ignore all ICMP ECHO |
|
requests sent to it over the IPv6 protocol destined to anycast address. |
|
|
|
Default: 0 |
|
|
|
xfrm6_gc_thresh - INTEGER |
|
(Obsolete since linux-4.14) |
|
The threshold at which we will start garbage collecting for IPv6 |
|
destination cache entries. At twice this value the system will |
|
refuse new allocations. |
|
|
|
|
|
IPv6 Update by: |
|
Pekka Savola <[email protected]> |
|
YOSHIFUJI Hideaki / USAGI Project <[email protected]> |
|
|
|
|
|
/proc/sys/net/bridge/* Variables: |
|
================================= |
|
|
|
bridge-nf-call-arptables - BOOLEAN |
|
- 1 : pass bridged ARP traffic to arptables' FORWARD chain. |
|
- 0 : disable this. |
|
|
|
Default: 1 |
|
|
|
bridge-nf-call-iptables - BOOLEAN |
|
- 1 : pass bridged IPv4 traffic to iptables' chains. |
|
- 0 : disable this. |
|
|
|
Default: 1 |
|
|
|
bridge-nf-call-ip6tables - BOOLEAN |
|
- 1 : pass bridged IPv6 traffic to ip6tables' chains. |
|
- 0 : disable this. |
|
|
|
Default: 1 |
|
|
|
bridge-nf-filter-vlan-tagged - BOOLEAN |
|
- 1 : pass bridged vlan-tagged ARP/IP/IPv6 traffic to {arp,ip,ip6}tables. |
|
- 0 : disable this. |
|
|
|
Default: 0 |
|
|
|
bridge-nf-filter-pppoe-tagged - BOOLEAN |
|
- 1 : pass bridged pppoe-tagged IP/IPv6 traffic to {ip,ip6}tables. |
|
- 0 : disable this. |
|
|
|
Default: 0 |
|
|
|
bridge-nf-pass-vlan-input-dev - BOOLEAN |
|
- 1: if bridge-nf-filter-vlan-tagged is enabled, try to find a vlan |
|
interface on the bridge and set the netfilter input device to the |
|
vlan. This allows use of e.g. "iptables -i br0.1" and makes the |
|
REDIRECT target work with vlan-on-top-of-bridge interfaces. When no |
|
matching vlan interface is found, or this switch is off, the input |
|
device is set to the bridge interface. |
|
|
|
- 0: disable bridge netfilter vlan interface lookup. |
|
|
|
Default: 0 |
|
|
|
``proc/sys/net/sctp/*`` Variables: |
|
================================== |
|
|
|
addip_enable - BOOLEAN |
|
Enable or disable extension of Dynamic Address Reconfiguration |
|
(ADD-IP) functionality specified in RFC5061. This extension provides |
|
the ability to dynamically add and remove new addresses for the SCTP |
|
associations. |
|
|
|
1: Enable extension. |
|
|
|
0: Disable extension. |
|
|
|
Default: 0 |
|
|
|
pf_enable - INTEGER |
|
Enable or disable pf (pf is short for potentially failed) state. A value |
|
of pf_retrans > path_max_retrans also disables pf state. That is, one of |
|
both pf_enable and pf_retrans > path_max_retrans can disable pf state. |
|
Since pf_retrans and path_max_retrans can be changed by userspace |
|
application, sometimes user expects to disable pf state by the value of |
|
pf_retrans > path_max_retrans, but occasionally the value of pf_retrans |
|
or path_max_retrans is changed by the user application, this pf state is |
|
enabled. As such, it is necessary to add this to dynamically enable |
|
and disable pf state. See: |
|
https://datatracker.ietf.org/doc/draft-ietf-tsvwg-sctp-failover for |
|
details. |
|
|
|
1: Enable pf. |
|
|
|
0: Disable pf. |
|
|
|
Default: 1 |
|
|
|
pf_expose - INTEGER |
|
Unset or enable/disable pf (pf is short for potentially failed) state |
|
exposure. Applications can control the exposure of the PF path state |
|
in the SCTP_PEER_ADDR_CHANGE event and the SCTP_GET_PEER_ADDR_INFO |
|
sockopt. When it's unset, no SCTP_PEER_ADDR_CHANGE event with |
|
SCTP_ADDR_PF state will be sent and a SCTP_PF-state transport info |
|
can be got via SCTP_GET_PEER_ADDR_INFO sockopt; When it's enabled, |
|
a SCTP_PEER_ADDR_CHANGE event will be sent for a transport becoming |
|
SCTP_PF state and a SCTP_PF-state transport info can be got via |
|
SCTP_GET_PEER_ADDR_INFO sockopt; When it's diabled, no |
|
SCTP_PEER_ADDR_CHANGE event will be sent and it returns -EACCES when |
|
trying to get a SCTP_PF-state transport info via SCTP_GET_PEER_ADDR_INFO |
|
sockopt. |
|
|
|
0: Unset pf state exposure, Compatible with old applications. |
|
|
|
1: Disable pf state exposure. |
|
|
|
2: Enable pf state exposure. |
|
|
|
Default: 0 |
|
|
|
addip_noauth_enable - BOOLEAN |
|
Dynamic Address Reconfiguration (ADD-IP) requires the use of |
|
authentication to protect the operations of adding or removing new |
|
addresses. This requirement is mandated so that unauthorized hosts |
|
would not be able to hijack associations. However, older |
|
implementations may not have implemented this requirement while |
|
allowing the ADD-IP extension. For reasons of interoperability, |
|
we provide this variable to control the enforcement of the |
|
authentication requirement. |
|
|
|
== =============================================================== |
|
1 Allow ADD-IP extension to be used without authentication. This |
|
should only be set in a closed environment for interoperability |
|
with older implementations. |
|
|
|
0 Enforce the authentication requirement |
|
== =============================================================== |
|
|
|
Default: 0 |
|
|
|
auth_enable - BOOLEAN |
|
Enable or disable Authenticated Chunks extension. This extension |
|
provides the ability to send and receive authenticated chunks and is |
|
required for secure operation of Dynamic Address Reconfiguration |
|
(ADD-IP) extension. |
|
|
|
- 1: Enable this extension. |
|
- 0: Disable this extension. |
|
|
|
Default: 0 |
|
|
|
prsctp_enable - BOOLEAN |
|
Enable or disable the Partial Reliability extension (RFC3758) which |
|
is used to notify peers that a given DATA should no longer be expected. |
|
|
|
- 1: Enable extension |
|
- 0: Disable |
|
|
|
Default: 1 |
|
|
|
max_burst - INTEGER |
|
The limit of the number of new packets that can be initially sent. It |
|
controls how bursty the generated traffic can be. |
|
|
|
Default: 4 |
|
|
|
association_max_retrans - INTEGER |
|
Set the maximum number for retransmissions that an association can |
|
attempt deciding that the remote end is unreachable. If this value |
|
is exceeded, the association is terminated. |
|
|
|
Default: 10 |
|
|
|
max_init_retransmits - INTEGER |
|
The maximum number of retransmissions of INIT and COOKIE-ECHO chunks |
|
that an association will attempt before declaring the destination |
|
unreachable and terminating. |
|
|
|
Default: 8 |
|
|
|
path_max_retrans - INTEGER |
|
The maximum number of retransmissions that will be attempted on a given |
|
path. Once this threshold is exceeded, the path is considered |
|
unreachable, and new traffic will use a different path when the |
|
association is multihomed. |
|
|
|
Default: 5 |
|
|
|
pf_retrans - INTEGER |
|
The number of retransmissions that will be attempted on a given path |
|
before traffic is redirected to an alternate transport (should one |
|
exist). Note this is distinct from path_max_retrans, as a path that |
|
passes the pf_retrans threshold can still be used. Its only |
|
deprioritized when a transmission path is selected by the stack. This |
|
setting is primarily used to enable fast failover mechanisms without |
|
having to reduce path_max_retrans to a very low value. See: |
|
http://www.ietf.org/id/draft-nishida-tsvwg-sctp-failover-05.txt |
|
for details. Note also that a value of pf_retrans > path_max_retrans |
|
disables this feature. Since both pf_retrans and path_max_retrans can |
|
be changed by userspace application, a variable pf_enable is used to |
|
disable pf state. |
|
|
|
Default: 0 |
|
|
|
ps_retrans - INTEGER |
|
Primary.Switchover.Max.Retrans (PSMR), it's a tunable parameter coming |
|
from section-5 "Primary Path Switchover" in rfc7829. The primary path |
|
will be changed to another active path when the path error counter on |
|
the old primary path exceeds PSMR, so that "the SCTP sender is allowed |
|
to continue data transmission on a new working path even when the old |
|
primary destination address becomes active again". Note this feature |
|
is disabled by initializing 'ps_retrans' per netns as 0xffff by default, |
|
and its value can't be less than 'pf_retrans' when changing by sysctl. |
|
|
|
Default: 0xffff |
|
|
|
rto_initial - INTEGER |
|
The initial round trip timeout value in milliseconds that will be used |
|
in calculating round trip times. This is the initial time interval |
|
for retransmissions. |
|
|
|
Default: 3000 |
|
|
|
rto_max - INTEGER |
|
The maximum value (in milliseconds) of the round trip timeout. This |
|
is the largest time interval that can elapse between retransmissions. |
|
|
|
Default: 60000 |
|
|
|
rto_min - INTEGER |
|
The minimum value (in milliseconds) of the round trip timeout. This |
|
is the smallest time interval the can elapse between retransmissions. |
|
|
|
Default: 1000 |
|
|
|
hb_interval - INTEGER |
|
The interval (in milliseconds) between HEARTBEAT chunks. These chunks |
|
are sent at the specified interval on idle paths to probe the state of |
|
a given path between 2 associations. |
|
|
|
Default: 30000 |
|
|
|
sack_timeout - INTEGER |
|
The amount of time (in milliseconds) that the implementation will wait |
|
to send a SACK. |
|
|
|
Default: 200 |
|
|
|
valid_cookie_life - INTEGER |
|
The default lifetime of the SCTP cookie (in milliseconds). The cookie |
|
is used during association establishment. |
|
|
|
Default: 60000 |
|
|
|
cookie_preserve_enable - BOOLEAN |
|
Enable or disable the ability to extend the lifetime of the SCTP cookie |
|
that is used during the establishment phase of SCTP association |
|
|
|
- 1: Enable cookie lifetime extension. |
|
- 0: Disable |
|
|
|
Default: 1 |
|
|
|
cookie_hmac_alg - STRING |
|
Select the hmac algorithm used when generating the cookie value sent by |
|
a listening sctp socket to a connecting client in the INIT-ACK chunk. |
|
Valid values are: |
|
|
|
* md5 |
|
* sha1 |
|
* none |
|
|
|
Ability to assign md5 or sha1 as the selected alg is predicated on the |
|
configuration of those algorithms at build time (CONFIG_CRYPTO_MD5 and |
|
CONFIG_CRYPTO_SHA1). |
|
|
|
Default: Dependent on configuration. MD5 if available, else SHA1 if |
|
available, else none. |
|
|
|
rcvbuf_policy - INTEGER |
|
Determines if the receive buffer is attributed to the socket or to |
|
association. SCTP supports the capability to create multiple |
|
associations on a single socket. When using this capability, it is |
|
possible that a single stalled association that's buffering a lot |
|
of data may block other associations from delivering their data by |
|
consuming all of the receive buffer space. To work around this, |
|
the rcvbuf_policy could be set to attribute the receiver buffer space |
|
to each association instead of the socket. This prevents the described |
|
blocking. |
|
|
|
- 1: rcvbuf space is per association |
|
- 0: rcvbuf space is per socket |
|
|
|
Default: 0 |
|
|
|
sndbuf_policy - INTEGER |
|
Similar to rcvbuf_policy above, this applies to send buffer space. |
|
|
|
- 1: Send buffer is tracked per association |
|
- 0: Send buffer is tracked per socket. |
|
|
|
Default: 0 |
|
|
|
sctp_mem - vector of 3 INTEGERs: min, pressure, max |
|
Number of pages allowed for queueing by all SCTP sockets. |
|
|
|
min: Below this number of pages SCTP is not bothered about its |
|
memory appetite. When amount of memory allocated by SCTP exceeds |
|
this number, SCTP starts to moderate memory usage. |
|
|
|
pressure: This value was introduced to follow format of tcp_mem. |
|
|
|
max: Number of pages allowed for queueing by all SCTP sockets. |
|
|
|
Default is calculated at boot time from amount of available memory. |
|
|
|
sctp_rmem - vector of 3 INTEGERs: min, default, max |
|
Only the first value ("min") is used, "default" and "max" are |
|
ignored. |
|
|
|
min: Minimal size of receive buffer used by SCTP socket. |
|
It is guaranteed to each SCTP socket (but not association) even |
|
under moderate memory pressure. |
|
|
|
Default: 4K |
|
|
|
sctp_wmem - vector of 3 INTEGERs: min, default, max |
|
Currently this tunable has no effect. |
|
|
|
addr_scope_policy - INTEGER |
|
Control IPv4 address scoping - draft-stewart-tsvwg-sctp-ipv4-00 |
|
|
|
- 0 - Disable IPv4 address scoping |
|
- 1 - Enable IPv4 address scoping |
|
- 2 - Follow draft but allow IPv4 private addresses |
|
- 3 - Follow draft but allow IPv4 link local addresses |
|
|
|
Default: 1 |
|
|
|
udp_port - INTEGER |
|
The listening port for the local UDP tunneling sock. Normally it's |
|
using the IANA-assigned UDP port number 9899 (sctp-tunneling). |
|
|
|
This UDP sock is used for processing the incoming UDP-encapsulated |
|
SCTP packets (from RFC6951), and shared by all applications in the |
|
same net namespace. This UDP sock will be closed when the value is |
|
set to 0. |
|
|
|
The value will also be used to set the src port of the UDP header |
|
for the outgoing UDP-encapsulated SCTP packets. For the dest port, |
|
please refer to 'encap_port' below. |
|
|
|
Default: 0 |
|
|
|
encap_port - INTEGER |
|
The default remote UDP encapsulation port. |
|
|
|
This value is used to set the dest port of the UDP header for the |
|
outgoing UDP-encapsulated SCTP packets by default. Users can also |
|
change the value for each sock/asoc/transport by using setsockopt. |
|
For further information, please refer to RFC6951. |
|
|
|
Note that when connecting to a remote server, the client should set |
|
this to the port that the UDP tunneling sock on the peer server is |
|
listening to and the local UDP tunneling sock on the client also |
|
must be started. On the server, it would get the encap_port from |
|
the incoming packet's source port. |
|
|
|
Default: 0 |
|
|
|
|
|
``/proc/sys/net/core/*`` |
|
======================== |
|
|
|
Please see: Documentation/admin-guide/sysctl/net.rst for descriptions of these entries. |
|
|
|
|
|
``/proc/sys/net/unix/*`` |
|
======================== |
|
|
|
max_dgram_qlen - INTEGER |
|
The maximum length of dgram socket receive queue |
|
|
|
Default: 10 |
|
|
|
|