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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/proc/sys/net/ipv4/* Variables:
2
3ip_forward - BOOLEAN
4 0 - disabled (default)
5 not 0 - enabled
6
7 Forward Packets between interfaces.
8
9 This variable is special, its change resets all configuration
10 parameters to their default state (RFC1122 for hosts, RFC1812
11 for routers)
12
13ip_default_ttl - INTEGER
14 default 64
15
16ip_no_pmtu_disc - BOOLEAN
17 Disable Path MTU Discovery.
18 default FALSE
19
20min_pmtu - INTEGER
21 default 562 - minimum discovered Path MTU
22
23mtu_expires - INTEGER
24 Time, in seconds, that cached PMTU information is kept.
25
26min_adv_mss - INTEGER
27 The advertised MSS depends on the first hop route MTU, but will
28 never be lower than this setting.
29
30IP Fragmentation:
31
32ipfrag_high_thresh - INTEGER
33 Maximum memory used to reassemble IP fragments. When
34 ipfrag_high_thresh bytes of memory is allocated for this purpose,
35 the fragment handler will toss packets until ipfrag_low_thresh
36 is reached.
37
38ipfrag_low_thresh - INTEGER
39 See ipfrag_high_thresh
40
41ipfrag_time - INTEGER
42 Time in seconds to keep an IP fragment in memory.
43
44ipfrag_secret_interval - INTEGER
45 Regeneration interval (in seconds) of the hash secret (or lifetime
46 for the hash secret) for IP fragments.
47 Default: 600
48
Herbert Xu89cee8b2005-12-13 23:14:27 -080049ipfrag_max_dist - INTEGER
50 ipfrag_max_dist is a non-negative integer value which defines the
51 maximum "disorder" which is allowed among fragments which share a
52 common IP source address. Note that reordering of packets is
53 not unusual, but if a large number of fragments arrive from a source
54 IP address while a particular fragment queue remains incomplete, it
55 probably indicates that one or more fragments belonging to that queue
56 have been lost. When ipfrag_max_dist is positive, an additional check
57 is done on fragments before they are added to a reassembly queue - if
58 ipfrag_max_dist (or more) fragments have arrived from a particular IP
59 address between additions to any IP fragment queue using that source
60 address, it's presumed that one or more fragments in the queue are
61 lost. The existing fragment queue will be dropped, and a new one
62 started. An ipfrag_max_dist value of zero disables this check.
63
64 Using a very small value, e.g. 1 or 2, for ipfrag_max_dist can
65 result in unnecessarily dropping fragment queues when normal
66 reordering of packets occurs, which could lead to poor application
67 performance. Using a very large value, e.g. 50000, increases the
68 likelihood of incorrectly reassembling IP fragments that originate
69 from different IP datagrams, which could result in data corruption.
70 Default: 64
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072INET peer storage:
73
74inet_peer_threshold - INTEGER
75 The approximate size of the storage. Starting from this threshold
76 entries will be thrown aggressively. This threshold also determines
77 entries' time-to-live and time intervals between garbage collection
78 passes. More entries, less time-to-live, less GC interval.
79
80inet_peer_minttl - INTEGER
81 Minimum time-to-live of entries. Should be enough to cover fragment
82 time-to-live on the reassembling side. This minimum time-to-live is
83 guaranteed if the pool size is less than inet_peer_threshold.
Stephen Hemminger77a538d2008-07-01 17:22:48 -070084 Measured in seconds.
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
86inet_peer_maxttl - INTEGER
87 Maximum time-to-live of entries. Unused entries will expire after
88 this period of time if there is no memory pressure on the pool (i.e.
89 when the number of entries in the pool is very small).
Stephen Hemminger77a538d2008-07-01 17:22:48 -070090 Measured in seconds.
Linus Torvalds1da177e2005-04-16 15:20:36 -070091
92inet_peer_gc_mintime - INTEGER
93 Minimum interval between garbage collection passes. This interval is
94 in effect under high memory pressure on the pool.
Stephen Hemminger77a538d2008-07-01 17:22:48 -070095 Measured in seconds.
Linus Torvalds1da177e2005-04-16 15:20:36 -070096
97inet_peer_gc_maxtime - INTEGER
98 Minimum interval between garbage collection passes. This interval is
99 in effect under low (or absent) memory pressure on the pool.
Stephen Hemminger77a538d2008-07-01 17:22:48 -0700100 Measured in seconds.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101
102TCP variables:
103
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800104somaxconn - INTEGER
105 Limit of socket listen() backlog, known in userspace as SOMAXCONN.
106 Defaults to 128. See also tcp_max_syn_backlog for additional tuning
107 for TCP sockets.
108
Stephen Hemminger9772efb2005-11-10 17:09:53 -0800109tcp_abc - INTEGER
Stephen Hemmingerb3a8a402006-09-13 19:51:02 -0700110 Controls Appropriate Byte Count (ABC) defined in RFC3465.
111 ABC is a way of increasing congestion window (cwnd) more slowly
112 in response to partial acknowledgments.
113 Possible values are:
114 0 increase cwnd once per acknowledgment (no ABC)
115 1 increase cwnd once per acknowledgment of full sized segment
116 2 allow increase cwnd by two if acknowledgment is
117 of two segments to compensate for delayed acknowledgments.
118 Default: 0 (off)
Stephen Hemminger9772efb2005-11-10 17:09:53 -0800119
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800120tcp_abort_on_overflow - BOOLEAN
121 If listening service is too slow to accept new connections,
122 reset them. Default state is FALSE. It means that if overflow
123 occurred due to a burst, connection will recover. Enable this
124 option _only_ if you are really sure that listening daemon
125 cannot be tuned to accept connections faster. Enabling this
126 option can harm clients of your server.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800128tcp_adv_win_scale - INTEGER
129 Count buffering overhead as bytes/2^tcp_adv_win_scale
130 (if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale),
131 if it is <= 0.
132 Default: 2
133
134tcp_allowed_congestion_control - STRING
135 Show/set the congestion control choices available to non-privileged
136 processes. The list is a subset of those listed in
137 tcp_available_congestion_control.
138 Default is "reno" and the default setting (tcp_congestion_control).
139
140tcp_app_win - INTEGER
141 Reserve max(window/2^tcp_app_win, mss) of window for application
142 buffer. Value 0 is special, it means that nothing is reserved.
143 Default: 31
144
145tcp_available_congestion_control - STRING
146 Shows the available congestion control choices that are registered.
147 More congestion control algorithms may be available as modules,
148 but not loaded.
149
John Heffner71599cd2007-02-27 10:03:56 -0800150tcp_base_mss - INTEGER
Stephen Hemminger4edc2f32008-07-10 16:50:26 -0700151 The initial value of search_low to be used by the packetization layer
152 Path MTU discovery (MTU probing). If MTU probing is enabled,
153 this is the initial MSS used by the connection.
John Heffner71599cd2007-02-27 10:03:56 -0800154
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800155tcp_congestion_control - STRING
156 Set the congestion control algorithm to be used for new
157 connections. The algorithm "reno" is always available, but
158 additional choices may be available based on kernel configuration.
159 Default is set as part of kernel configuration.
160
161tcp_dsack - BOOLEAN
162 Allows TCP to send "duplicate" SACKs.
163
164tcp_ecn - BOOLEAN
165 Enable Explicit Congestion Notification in TCP.
166
167tcp_fack - BOOLEAN
168 Enable FACK congestion avoidance and fast retransmission.
169 The value is not used, if tcp_sack is not enabled.
170
171tcp_fin_timeout - INTEGER
172 Time to hold socket in state FIN-WAIT-2, if it was closed
173 by our side. Peer can be broken and never close its side,
174 or even died unexpectedly. Default value is 60sec.
175 Usual value used in 2.2 was 180 seconds, you may restore
176 it, but remember that if your machine is even underloaded WEB server,
177 you risk to overflow memory with kilotons of dead sockets,
178 FIN-WAIT-2 sockets are less dangerous than FIN-WAIT-1,
179 because they eat maximum 1.5K of memory, but they tend
180 to live longer. Cf. tcp_max_orphans.
181
Ilpo Järvinen89808062007-02-27 10:10:55 -0800182tcp_frto - INTEGER
Ilpo Järvinencd998892007-09-20 11:35:26 -0700183 Enables Forward RTO-Recovery (F-RTO) defined in RFC4138.
184 F-RTO is an enhanced recovery algorithm for TCP retransmission
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800185 timeouts. It is particularly beneficial in wireless environments
186 where packet loss is typically due to random radio interference
Ryousei Takano564262c12007-10-25 23:03:52 -0700187 rather than intermediate router congestion. F-RTO is sender-side
Stephen Hemminger4edc2f32008-07-10 16:50:26 -0700188 only modification. Therefore it does not require any support from
189 the peer.
190
Ilpo Järvinencd998892007-09-20 11:35:26 -0700191 If set to 1, basic version is enabled. 2 enables SACK enhanced
192 F-RTO if flow uses SACK. The basic version can be used also when
Ryousei Takano564262c12007-10-25 23:03:52 -0700193 SACK is in use though scenario(s) with it exists where F-RTO
Ilpo Järvinencd998892007-09-20 11:35:26 -0700194 interacts badly with the packet counting of the SACK enabled TCP
195 flow.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196
Ilpo Järvinen89808062007-02-27 10:10:55 -0800197tcp_frto_response - INTEGER
198 When F-RTO has detected that a TCP retransmission timeout was
199 spurious (i.e, the timeout would have been avoided had TCP set a
200 longer retransmission timeout), TCP has several options what to do
201 next. Possible values are:
202 0 Rate halving based; a smooth and conservative response,
203 results in halved cwnd and ssthresh after one RTT
204 1 Very conservative response; not recommended because even
205 though being valid, it interacts poorly with the rest of
206 Linux TCP, halves cwnd and ssthresh immediately
207 2 Aggressive response; undoes congestion control measures
208 that are now known to be unnecessary (ignoring the
209 possibility of a lost retransmission that would require
210 TCP to be more cautious), cwnd and ssthresh are restored
211 to the values prior timeout
212 Default: 0 (rate halving based)
213
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214tcp_keepalive_time - INTEGER
215 How often TCP sends out keepalive messages when keepalive is enabled.
216 Default: 2hours.
217
218tcp_keepalive_probes - INTEGER
219 How many keepalive probes TCP sends out, until it decides that the
220 connection is broken. Default value: 9.
221
222tcp_keepalive_intvl - INTEGER
223 How frequently the probes are send out. Multiplied by
224 tcp_keepalive_probes it is time to kill not responding connection,
225 after probes started. Default value: 75sec i.e. connection
226 will be aborted after ~11 minutes of retries.
227
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800228tcp_low_latency - BOOLEAN
229 If set, the TCP stack makes decisions that prefer lower
230 latency as opposed to higher throughput. By default, this
231 option is not set meaning that higher throughput is preferred.
232 An example of an application where this default should be
233 changed would be a Beowulf compute cluster.
234 Default: 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235
236tcp_max_orphans - INTEGER
237 Maximal number of TCP sockets not attached to any user file handle,
238 held by system. If this number is exceeded orphaned connections are
239 reset immediately and warning is printed. This limit exists
240 only to prevent simple DoS attacks, you _must_ not rely on this
241 or lower the limit artificially, but rather increase it
242 (probably, after increasing installed memory),
243 if network conditions require more than default value,
244 and tune network services to linger and kill such states
245 more aggressively. Let me to remind again: each orphan eats
246 up to ~64K of unswappable memory.
247
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248tcp_max_syn_backlog - INTEGER
249 Maximal number of remembered connection requests, which are
250 still did not receive an acknowledgment from connecting client.
251 Default value is 1024 for systems with more than 128Mb of memory,
252 and 128 for low memory machines. If server suffers of overload,
253 try to increase this number.
254
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800255tcp_max_tw_buckets - INTEGER
256 Maximal number of timewait sockets held by system simultaneously.
257 If this number is exceeded time-wait socket is immediately destroyed
258 and warning is printed. This limit exists only to prevent
259 simple DoS attacks, you _must_ not lower the limit artificially,
260 but rather increase it (probably, after increasing installed memory),
261 if network conditions require more than default value.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800263tcp_mem - vector of 3 INTEGERs: min, pressure, max
264 min: below this number of pages TCP is not bothered about its
265 memory appetite.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800267 pressure: when amount of memory allocated by TCP exceeds this number
268 of pages, TCP moderates its memory consumption and enters memory
269 pressure mode, which is exited when memory consumption falls
270 under "min".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800272 max: number of pages allowed for queueing by all TCP sockets.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800274 Defaults are calculated at boot time from amount of available
275 memory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276
John Heffner71599cd2007-02-27 10:03:56 -0800277tcp_moderate_rcvbuf - BOOLEAN
Stephen Hemminger4edc2f32008-07-10 16:50:26 -0700278 If set, TCP performs receive buffer auto-tuning, attempting to
John Heffner71599cd2007-02-27 10:03:56 -0800279 automatically size the buffer (no greater than tcp_rmem[2]) to
280 match the size required by the path for full throughput. Enabled by
281 default.
282
283tcp_mtu_probing - INTEGER
284 Controls TCP Packetization-Layer Path MTU Discovery. Takes three
285 values:
286 0 - Disabled
287 1 - Disabled by default, enabled when an ICMP black hole detected
288 2 - Always enabled, use initial MSS of tcp_base_mss.
289
290tcp_no_metrics_save - BOOLEAN
291 By default, TCP saves various connection metrics in the route cache
292 when the connection closes, so that connections established in the
293 near future can use these to set initial conditions. Usually, this
294 increases overall performance, but may sometimes cause performance
Simon Arlott0f035b82007-10-20 01:30:25 +0200295 degradation. If set, TCP will not cache metrics on closing
John Heffner71599cd2007-02-27 10:03:56 -0800296 connections.
297
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800298tcp_orphan_retries - INTEGER
299 How may times to retry before killing TCP connection, closed
300 by our side. Default value 7 corresponds to ~50sec-16min
301 depending on RTO. If you machine is loaded WEB server,
302 you should think about lowering this value, such sockets
303 may consume significant resources. Cf. tcp_max_orphans.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304
305tcp_reordering - INTEGER
306 Maximal reordering of packets in a TCP stream.
307 Default: 3
308
309tcp_retrans_collapse - BOOLEAN
310 Bug-to-bug compatibility with some broken printers.
311 On retransmit try to send bigger packets to work around bugs in
312 certain TCP stacks.
313
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800314tcp_retries1 - INTEGER
315 How many times to retry before deciding that something is wrong
316 and it is necessary to report this suspicion to network layer.
317 Minimal RFC value is 3, it is default, which corresponds
318 to ~3sec-8min depending on RTO.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800320tcp_retries2 - INTEGER
321 How may times to retry before killing alive TCP connection.
322 RFC1122 says that the limit should be longer than 100 sec.
323 It is too small number. Default value 15 corresponds to ~13-30min
324 depending on RTO.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800326tcp_rfc1337 - BOOLEAN
327 If set, the TCP stack behaves conforming to RFC1337. If unset,
328 we are not conforming to RFC, but prevent TCP TIME_WAIT
329 assassination.
330 Default: 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331
332tcp_rmem - vector of 3 INTEGERs: min, default, max
333 min: Minimal size of receive buffer used by TCP sockets.
334 It is guaranteed to each TCP socket, even under moderate memory
335 pressure.
336 Default: 8K
337
J. Bruce Fields53025f52008-07-10 16:47:41 -0700338 default: initial size of receive buffer used by TCP sockets.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 This value overrides net.core.rmem_default used by other protocols.
340 Default: 87380 bytes. This value results in window of 65535 with
341 default setting of tcp_adv_win_scale and tcp_app_win:0 and a bit
342 less for default tcp_app_win. See below about these variables.
343
344 max: maximal size of receive buffer allowed for automatically
345 selected receiver buffers for TCP socket. This value does not override
J. Bruce Fields53025f52008-07-10 16:47:41 -0700346 net.core.rmem_max. Calling setsockopt() with SO_RCVBUF disables
347 automatic tuning of that socket's receive buffer size, in which
348 case this value is ignored.
349 Default: between 87380B and 4MB, depending on RAM size.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800351tcp_sack - BOOLEAN
352 Enable select acknowledgments (SACKS).
Rick Jones15d99e02006-03-20 22:40:29 -0800353
David S. Miller35089bb2006-06-13 22:33:04 -0700354tcp_slow_start_after_idle - BOOLEAN
355 If set, provide RFC2861 behavior and time out the congestion
356 window after an idle period. An idle period is defined at
357 the current RTO. If unset, the congestion window will not
358 be timed out after an idle period.
359 Default: 1
360
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800361tcp_stdurg - BOOLEAN
Stephen Hemminger4edc2f32008-07-10 16:50:26 -0700362 Use the Host requirements interpretation of the TCP urgent pointer field.
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800363 Most hosts use the older BSD interpretation, so if you turn this on
364 Linux might not communicate correctly with them.
365 Default: FALSE
366
367tcp_synack_retries - INTEGER
368 Number of times SYNACKs for a passive TCP connection attempt will
369 be retransmitted. Should not be higher than 255. Default value
370 is 5, which corresponds to ~180seconds.
371
372tcp_syncookies - BOOLEAN
373 Only valid when the kernel was compiled with CONFIG_SYNCOOKIES
374 Send out syncookies when the syn backlog queue of a socket
Stephen Hemminger4edc2f32008-07-10 16:50:26 -0700375 overflows. This is to prevent against the common 'SYN flood attack'
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800376 Default: FALSE
377
378 Note, that syncookies is fallback facility.
379 It MUST NOT be used to help highly loaded servers to stand
Stephen Hemminger4edc2f32008-07-10 16:50:26 -0700380 against legal connection rate. If you see SYN flood warnings
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800381 in your logs, but investigation shows that they occur
382 because of overload with legal connections, you should tune
383 another parameters until this warning disappear.
384 See: tcp_max_syn_backlog, tcp_synack_retries, tcp_abort_on_overflow.
385
386 syncookies seriously violate TCP protocol, do not allow
387 to use TCP extensions, can result in serious degradation
388 of some services (f.e. SMTP relaying), visible not by you,
389 but your clients and relays, contacting you. While you see
Stephen Hemminger4edc2f32008-07-10 16:50:26 -0700390 SYN flood warnings in logs not being really flooded, your server
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800391 is seriously misconfigured.
392
393tcp_syn_retries - INTEGER
394 Number of times initial SYNs for an active TCP connection attempt
395 will be retransmitted. Should not be higher than 255. Default value
396 is 5, which corresponds to ~180seconds.
397
398tcp_timestamps - BOOLEAN
399 Enable timestamps as defined in RFC1323.
400
401tcp_tso_win_divisor - INTEGER
402 This allows control over what percentage of the congestion window
403 can be consumed by a single TSO frame.
404 The setting of this parameter is a choice between burstiness and
405 building larger TSO frames.
406 Default: 3
407
408tcp_tw_recycle - BOOLEAN
409 Enable fast recycling TIME-WAIT sockets. Default value is 0.
410 It should not be changed without advice/request of technical
411 experts.
412
413tcp_tw_reuse - BOOLEAN
414 Allow to reuse TIME-WAIT sockets for new connections when it is
415 safe from protocol viewpoint. Default value is 0.
416 It should not be changed without advice/request of technical
417 experts.
418
419tcp_window_scaling - BOOLEAN
420 Enable window scaling as defined in RFC1323.
421
422tcp_wmem - vector of 3 INTEGERs: min, default, max
J. Bruce Fields53025f52008-07-10 16:47:41 -0700423 min: Amount of memory reserved for send buffers for TCP sockets.
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800424 Each TCP socket has rights to use it due to fact of its birth.
425 Default: 4K
426
J. Bruce Fields53025f52008-07-10 16:47:41 -0700427 default: initial size of send buffer used by TCP sockets. This
428 value overrides net.core.wmem_default used by other protocols.
429 It is usually lower than net.core.wmem_default.
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800430 Default: 16K
431
J. Bruce Fields53025f52008-07-10 16:47:41 -0700432 max: Maximal amount of memory allowed for automatically tuned
433 send buffers for TCP sockets. This value does not override
434 net.core.wmem_max. Calling setsockopt() with SO_SNDBUF disables
435 automatic tuning of that socket's send buffer size, in which case
436 this value is ignored.
437 Default: between 64K and 4MB, depending on RAM size.
Stephen Hemmingeref56e622006-11-09 16:37:26 -0800438
439tcp_workaround_signed_windows - BOOLEAN
440 If set, assume no receipt of a window scaling option means the
441 remote TCP is broken and treats the window as a signed quantity.
442 If unset, assume the remote TCP is not broken even if we do
443 not receive a window scaling option from them.
444 Default: 0
445
Chris Leech72d0b7a2007-03-08 09:57:35 -0800446tcp_dma_copybreak - INTEGER
447 Lower limit, in bytes, of the size of socket reads that will be
448 offloaded to a DMA copy engine, if one is present in the system
449 and CONFIG_NET_DMA is enabled.
450 Default: 4096
451
Hideo Aoki95766ff2007-12-31 00:29:24 -0800452UDP variables:
453
454udp_mem - vector of 3 INTEGERs: min, pressure, max
455 Number of pages allowed for queueing by all UDP sockets.
456
457 min: Below this number of pages UDP is not bothered about its
458 memory appetite. When amount of memory allocated by UDP exceeds
459 this number, UDP starts to moderate memory usage.
460
461 pressure: This value was introduced to follow format of tcp_mem.
462
463 max: Number of pages allowed for queueing by all UDP sockets.
464
465 Default is calculated at boot time from amount of available memory.
466
467udp_rmem_min - INTEGER
468 Minimal size of receive buffer used by UDP sockets in moderation.
469 Each UDP socket is able to use the size for receiving data, even if
470 total pages of UDP sockets exceed udp_mem pressure. The unit is byte.
471 Default: 4096
472
473udp_wmem_min - INTEGER
474 Minimal size of send buffer used by UDP sockets in moderation.
475 Each UDP socket is able to use the size for sending data, even if
476 total pages of UDP sockets exceed udp_mem pressure. The unit is byte.
477 Default: 4096
478
Paul Moore8802f612006-08-03 16:45:49 -0700479CIPSOv4 Variables:
480
481cipso_cache_enable - BOOLEAN
482 If set, enable additions to and lookups from the CIPSO label mapping
483 cache. If unset, additions are ignored and lookups always result in a
484 miss. However, regardless of the setting the cache is still
485 invalidated when required when means you can safely toggle this on and
486 off and the cache will always be "safe".
487 Default: 1
488
489cipso_cache_bucket_size - INTEGER
490 The CIPSO label cache consists of a fixed size hash table with each
491 hash bucket containing a number of cache entries. This variable limits
492 the number of entries in each hash bucket; the larger the value the
493 more CIPSO label mappings that can be cached. When the number of
494 entries in a given hash bucket reaches this limit adding new entries
495 causes the oldest entry in the bucket to be removed to make room.
496 Default: 10
497
498cipso_rbm_optfmt - BOOLEAN
499 Enable the "Optimized Tag 1 Format" as defined in section 3.4.2.6 of
500 the CIPSO draft specification (see Documentation/netlabel for details).
501 This means that when set the CIPSO tag will be padded with empty
502 categories in order to make the packet data 32-bit aligned.
503 Default: 0
504
505cipso_rbm_structvalid - BOOLEAN
506 If set, do a very strict check of the CIPSO option when
507 ip_options_compile() is called. If unset, relax the checks done during
508 ip_options_compile(). Either way is "safe" as errors are caught else
509 where in the CIPSO processing code but setting this to 0 (False) should
510 result in less work (i.e. it should be faster) but could cause problems
511 with other implementations that require strict checking.
512 Default: 0
513
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514IP Variables:
515
516ip_local_port_range - 2 INTEGERS
517 Defines the local port range that is used by TCP and UDP to
518 choose the local port. The first number is the first, the
519 second the last local port number. Default value depends on
520 amount of memory available on the system:
521 > 128Mb 32768-61000
522 < 128Mb 1024-4999 or even less.
523 This number defines number of active connections, which this
524 system can issue simultaneously to systems not supporting
525 TCP extensions (timestamps). With tcp_tw_recycle enabled
526 (i.e. by default) range 1024-4999 is enough to issue up to
527 2000 connections per second to systems supporting timestamps.
528
529ip_nonlocal_bind - BOOLEAN
530 If set, allows processes to bind() to non-local IP addresses,
531 which can be quite useful - but may break some applications.
532 Default: 0
533
534ip_dynaddr - BOOLEAN
535 If set non-zero, enables support for dynamic addresses.
536 If set to a non-zero value larger than 1, a kernel log
537 message will be printed when dynamic address rewriting
538 occurs.
539 Default: 0
540
541icmp_echo_ignore_all - BOOLEAN
David S. Miller7ce312462005-10-03 16:07:30 -0700542 If set non-zero, then the kernel will ignore all ICMP ECHO
543 requests sent to it.
544 Default: 0
545
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546icmp_echo_ignore_broadcasts - BOOLEAN
David S. Miller7ce312462005-10-03 16:07:30 -0700547 If set non-zero, then the kernel will ignore all ICMP ECHO and
548 TIMESTAMP requests sent to it via broadcast/multicast.
549 Default: 1
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550
551icmp_ratelimit - INTEGER
552 Limit the maximal rates for sending ICMP packets whose type matches
553 icmp_ratemask (see below) to specific targets.
Stephen Hemminger6dbf4bc2008-07-01 19:29:07 -0700554 0 to disable any limiting,
555 otherwise the minimal space between responses in milliseconds.
556 Default: 1000
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557
558icmp_ratemask - INTEGER
559 Mask made of ICMP types for which rates are being limited.
560 Significant bits: IHGFEDCBA9876543210
561 Default mask: 0000001100000011000 (6168)
562
563 Bit definitions (see include/linux/icmp.h):
564 0 Echo Reply
565 3 Destination Unreachable *
566 4 Source Quench *
567 5 Redirect
568 8 Echo Request
569 B Time Exceeded *
570 C Parameter Problem *
571 D Timestamp Request
572 E Timestamp Reply
573 F Info Request
574 G Info Reply
575 H Address Mask Request
576 I Address Mask Reply
577
578 * These are rate limited by default (see default mask above)
579
580icmp_ignore_bogus_error_responses - BOOLEAN
581 Some routers violate RFC1122 by sending bogus responses to broadcast
582 frames. Such violations are normally logged via a kernel warning.
583 If this is set to TRUE, the kernel will not give such warnings, which
584 will avoid log file clutter.
585 Default: FALSE
586
Horms95f7daf2006-02-02 17:02:25 -0800587icmp_errors_use_inbound_ifaddr - BOOLEAN
588
589 If zero, icmp error messages are sent with the primary address of
590 the exiting interface.
591
592 If non-zero, the message will be sent with the primary address of
593 the interface that received the packet that caused the icmp error.
594 This is the behaviour network many administrators will expect from
595 a router. And it can make debugging complicated network layouts
596 much easier.
597
598 Note that if no primary address exists for the interface selected,
599 then the primary address of the first non-loopback interface that
Matt LaPlanted6bc8ac2006-10-03 22:54:15 +0200600 has one will be used regardless of this setting.
Horms95f7daf2006-02-02 17:02:25 -0800601
602 Default: 0
603
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604igmp_max_memberships - INTEGER
605 Change the maximum number of multicast groups we can subscribe to.
606 Default: 20
607
608conf/interface/* changes special settings per interface (where "interface" is
609 the name of your network interface)
610conf/all/* is special, changes the settings for all interfaces
611
612
613log_martians - BOOLEAN
614 Log packets with impossible addresses to kernel log.
615 log_martians for the interface will be enabled if at least one of
616 conf/{all,interface}/log_martians is set to TRUE,
617 it will be disabled otherwise
618
619accept_redirects - BOOLEAN
620 Accept ICMP redirect messages.
621 accept_redirects for the interface will be enabled if:
622 - both conf/{all,interface}/accept_redirects are TRUE in the case forwarding
623 for the interface is enabled
624 or
625 - at least one of conf/{all,interface}/accept_redirects is TRUE in the case
626 forwarding for the interface is disabled
627 accept_redirects for the interface will be disabled otherwise
628 default TRUE (host)
629 FALSE (router)
630
631forwarding - BOOLEAN
632 Enable IP forwarding on this interface.
633
634mc_forwarding - BOOLEAN
635 Do multicast routing. The kernel needs to be compiled with CONFIG_MROUTE
636 and a multicast routing daemon is required.
637 conf/all/mc_forwarding must also be set to TRUE to enable multicast routing
638 for the interface
639
640medium_id - INTEGER
641 Integer value used to differentiate the devices by the medium they
642 are attached to. Two devices can have different id values when
643 the broadcast packets are received only on one of them.
644 The default value 0 means that the device is the only interface
645 to its medium, value of -1 means that medium is not known.
646
647 Currently, it is used to change the proxy_arp behavior:
648 the proxy_arp feature is enabled for packets forwarded between
649 two devices attached to different media.
650
651proxy_arp - BOOLEAN
652 Do proxy arp.
653 proxy_arp for the interface will be enabled if at least one of
654 conf/{all,interface}/proxy_arp is set to TRUE,
655 it will be disabled otherwise
656
657shared_media - BOOLEAN
658 Send(router) or accept(host) RFC1620 shared media redirects.
659 Overrides ip_secure_redirects.
660 shared_media for the interface will be enabled if at least one of
661 conf/{all,interface}/shared_media is set to TRUE,
662 it will be disabled otherwise
663 default TRUE
664
665secure_redirects - BOOLEAN
666 Accept ICMP redirect messages only for gateways,
667 listed in default gateway list.
668 secure_redirects for the interface will be enabled if at least one of
669 conf/{all,interface}/secure_redirects is set to TRUE,
670 it will be disabled otherwise
671 default TRUE
672
673send_redirects - BOOLEAN
674 Send redirects, if router.
675 send_redirects for the interface will be enabled if at least one of
676 conf/{all,interface}/send_redirects is set to TRUE,
677 it will be disabled otherwise
678 Default: TRUE
679
680bootp_relay - BOOLEAN
681 Accept packets with source address 0.b.c.d destined
682 not to this host as local ones. It is supposed, that
683 BOOTP relay daemon will catch and forward such packets.
684 conf/all/bootp_relay must also be set to TRUE to enable BOOTP relay
685 for the interface
686 default FALSE
687 Not Implemented Yet.
688
689accept_source_route - BOOLEAN
690 Accept packets with SRR option.
691 conf/all/accept_source_route must also be set to TRUE to accept packets
692 with SRR option on the interface
693 default TRUE (router)
694 FALSE (host)
695
696rp_filter - BOOLEAN
697 1 - do source validation by reversed path, as specified in RFC1812
698 Recommended option for single homed hosts and stub network
699 routers. Could cause troubles for complicated (not loop free)
700 networks running a slow unreliable protocol (sort of RIP),
701 or using static routes.
702
703 0 - No source validation.
704
705 conf/all/rp_filter must also be set to TRUE to do source validation
706 on the interface
707
708 Default value is 0. Note that some distributions enable it
709 in startup scripts.
710
711arp_filter - BOOLEAN
712 1 - Allows you to have multiple network interfaces on the same
713 subnet, and have the ARPs for each interface be answered
714 based on whether or not the kernel would route a packet from
715 the ARP'd IP out that interface (therefore you must use source
716 based routing for this to work). In other words it allows control
717 of which cards (usually 1) will respond to an arp request.
718
719 0 - (default) The kernel can respond to arp requests with addresses
720 from other interfaces. This may seem wrong but it usually makes
721 sense, because it increases the chance of successful communication.
722 IP addresses are owned by the complete host on Linux, not by
723 particular interfaces. Only for more complex setups like load-
724 balancing, does this behaviour cause problems.
725
726 arp_filter for the interface will be enabled if at least one of
727 conf/{all,interface}/arp_filter is set to TRUE,
728 it will be disabled otherwise
729
730arp_announce - INTEGER
731 Define different restriction levels for announcing the local
732 source IP address from IP packets in ARP requests sent on
733 interface:
734 0 - (default) Use any local address, configured on any interface
735 1 - Try to avoid local addresses that are not in the target's
736 subnet for this interface. This mode is useful when target
737 hosts reachable via this interface require the source IP
738 address in ARP requests to be part of their logical network
739 configured on the receiving interface. When we generate the
740 request we will check all our subnets that include the
741 target IP and will preserve the source address if it is from
742 such subnet. If there is no such subnet we select source
743 address according to the rules for level 2.
744 2 - Always use the best local address for this target.
745 In this mode we ignore the source address in the IP packet
746 and try to select local address that we prefer for talks with
747 the target host. Such local address is selected by looking
748 for primary IP addresses on all our subnets on the outgoing
749 interface that include the target IP address. If no suitable
750 local address is found we select the first local address
751 we have on the outgoing interface or on all other interfaces,
752 with the hope we will receive reply for our request and
753 even sometimes no matter the source IP address we announce.
754
755 The max value from conf/{all,interface}/arp_announce is used.
756
757 Increasing the restriction level gives more chance for
758 receiving answer from the resolved target while decreasing
759 the level announces more valid sender's information.
760
761arp_ignore - INTEGER
762 Define different modes for sending replies in response to
763 received ARP requests that resolve local target IP addresses:
764 0 - (default): reply for any local target IP address, configured
765 on any interface
766 1 - reply only if the target IP address is local address
767 configured on the incoming interface
768 2 - reply only if the target IP address is local address
769 configured on the incoming interface and both with the
770 sender's IP address are part from same subnet on this interface
771 3 - do not reply for local addresses configured with scope host,
772 only resolutions for global and link addresses are replied
773 4-7 - reserved
774 8 - do not reply for all local addresses
775
776 The max value from conf/{all,interface}/arp_ignore is used
777 when ARP request is received on the {interface}
778
Neil Hormanc1b1bce2006-03-20 22:40:03 -0800779arp_accept - BOOLEAN
780 Define behavior when gratuitous arp replies are received:
781 0 - drop gratuitous arp frames
782 1 - accept gratuitous arp frames
783
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784app_solicit - INTEGER
785 The maximum number of probes to send to the user space ARP daemon
786 via netlink before dropping back to multicast probes (see
787 mcast_solicit). Defaults to 0.
788
789disable_policy - BOOLEAN
790 Disable IPSEC policy (SPD) for this interface
791
792disable_xfrm - BOOLEAN
793 Disable IPSEC encryption on this interface, whatever the policy
794
795
796
797tag - INTEGER
798 Allows you to write a number, which can be used as required.
799 Default value is 0.
800
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801Alexey Kuznetsov.
802kuznet@ms2.inr.ac.ru
803
804Updated by:
805Andi Kleen
806ak@muc.de
807Nicolas Delon
808delon.nicolas@wanadoo.fr
809
810
811
812
813/proc/sys/net/ipv6/* Variables:
814
815IPv6 has no global variables such as tcp_*. tcp_* settings under ipv4/ also
816apply to IPv6 [XXX?].
817
818bindv6only - BOOLEAN
819 Default value for IPV6_V6ONLY socket option,
820 which restricts use of the IPv6 socket to IPv6 communication
821 only.
822 TRUE: disable IPv4-mapped address feature
823 FALSE: enable IPv4-mapped address feature
824
825 Default: FALSE (as specified in RFC2553bis)
826
827IPv6 Fragmentation:
828
829ip6frag_high_thresh - INTEGER
830 Maximum memory used to reassemble IPv6 fragments. When
831 ip6frag_high_thresh bytes of memory is allocated for this purpose,
832 the fragment handler will toss packets until ip6frag_low_thresh
833 is reached.
834
835ip6frag_low_thresh - INTEGER
836 See ip6frag_high_thresh
837
838ip6frag_time - INTEGER
839 Time in seconds to keep an IPv6 fragment in memory.
840
841ip6frag_secret_interval - INTEGER
842 Regeneration interval (in seconds) of the hash secret (or lifetime
843 for the hash secret) for IPv6 fragments.
844 Default: 600
845
846conf/default/*:
847 Change the interface-specific default settings.
848
849
850conf/all/*:
851 Change all the interface-specific settings.
852
853 [XXX: Other special features than forwarding?]
854
855conf/all/forwarding - BOOLEAN
856 Enable global IPv6 forwarding between all interfaces.
857
858 IPv4 and IPv6 work differently here; e.g. netfilter must be used
859 to control which interfaces may forward packets and which not.
860
861 This also sets all interfaces' Host/Router setting
862 'forwarding' to the specified value. See below for details.
863
864 This referred to as global forwarding.
865
YOSHIFUJI Hideakifbea49e2006-09-22 14:43:49 -0700866proxy_ndp - BOOLEAN
867 Do proxy ndp.
868
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869conf/interface/*:
870 Change special settings per interface.
871
872 The functional behaviour for certain settings is different
873 depending on whether local forwarding is enabled or not.
874
875accept_ra - BOOLEAN
876 Accept Router Advertisements; autoconfigure using them.
877
878 Functional default: enabled if local forwarding is disabled.
879 disabled if local forwarding is enabled.
880
YOSHIFUJI Hideaki65f5c7c2006-03-20 16:55:08 -0800881accept_ra_defrtr - BOOLEAN
882 Learn default router in Router Advertisement.
883
884 Functional default: enabled if accept_ra is enabled.
885 disabled if accept_ra is disabled.
886
YOSHIFUJI Hideakic4fd30e2006-03-20 16:55:26 -0800887accept_ra_pinfo - BOOLEAN
Matt LaPlante2fe0ae72006-10-03 22:50:39 +0200888 Learn Prefix Information in Router Advertisement.
YOSHIFUJI Hideakic4fd30e2006-03-20 16:55:26 -0800889
890 Functional default: enabled if accept_ra is enabled.
891 disabled if accept_ra is disabled.
892
YOSHIFUJI Hideaki09c884d2006-03-20 17:07:03 -0800893accept_ra_rt_info_max_plen - INTEGER
894 Maximum prefix length of Route Information in RA.
895
896 Route Information w/ prefix larger than or equal to this
897 variable shall be ignored.
898
899 Functional default: 0 if accept_ra_rtr_pref is enabled.
900 -1 if accept_ra_rtr_pref is disabled.
901
YOSHIFUJI Hideaki930d6ff2006-03-20 17:05:30 -0800902accept_ra_rtr_pref - BOOLEAN
903 Accept Router Preference in RA.
904
905 Functional default: enabled if accept_ra is enabled.
906 disabled if accept_ra is disabled.
907
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908accept_redirects - BOOLEAN
909 Accept Redirects.
910
911 Functional default: enabled if local forwarding is disabled.
912 disabled if local forwarding is enabled.
913
YOSHIFUJI Hideaki0bcbc922007-04-24 14:58:30 -0700914accept_source_route - INTEGER
915 Accept source routing (routing extension header).
916
YOSHIFUJI Hideakibb4dbf92007-07-10 22:55:49 -0700917 >= 0: Accept only routing header type 2.
YOSHIFUJI Hideaki0bcbc922007-04-24 14:58:30 -0700918 < 0: Do not accept routing header.
919
920 Default: 0
921
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922autoconf - BOOLEAN
923 Autoconfigure addresses using Prefix Information in Router
924 Advertisements.
925
YOSHIFUJI Hideakic4fd30e2006-03-20 16:55:26 -0800926 Functional default: enabled if accept_ra_pinfo is enabled.
927 disabled if accept_ra_pinfo is disabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928
929dad_transmits - INTEGER
930 The amount of Duplicate Address Detection probes to send.
931 Default: 1
932
933forwarding - BOOLEAN
934 Configure interface-specific Host/Router behaviour.
935
936 Note: It is recommended to have the same setting on all
937 interfaces; mixed router/host scenarios are rather uncommon.
938
939 FALSE:
940
941 By default, Host behaviour is assumed. This means:
942
943 1. IsRouter flag is not set in Neighbour Advertisements.
944 2. Router Solicitations are being sent when necessary.
945 3. If accept_ra is TRUE (default), accept Router
946 Advertisements (and do autoconfiguration).
947 4. If accept_redirects is TRUE (default), accept Redirects.
948
949 TRUE:
950
951 If local forwarding is enabled, Router behaviour is assumed.
952 This means exactly the reverse from the above:
953
954 1. IsRouter flag is set in Neighbour Advertisements.
955 2. Router Solicitations are not sent.
956 3. Router Advertisements are ignored.
957 4. Redirects are ignored.
958
959 Default: FALSE if global forwarding is disabled (default),
960 otherwise TRUE.
961
962hop_limit - INTEGER
963 Default Hop Limit to set.
964 Default: 64
965
966mtu - INTEGER
967 Default Maximum Transfer Unit
968 Default: 1280 (IPv6 required minimum)
969
YOSHIFUJI Hideaki52e16352006-03-20 17:05:47 -0800970router_probe_interval - INTEGER
971 Minimum interval (in seconds) between Router Probing described
972 in RFC4191.
973
974 Default: 60
975
Linus Torvalds1da177e2005-04-16 15:20:36 -0700976router_solicitation_delay - INTEGER
977 Number of seconds to wait after interface is brought up
978 before sending Router Solicitations.
979 Default: 1
980
981router_solicitation_interval - INTEGER
982 Number of seconds to wait between Router Solicitations.
983 Default: 4
984
985router_solicitations - INTEGER
986 Number of Router Solicitations to send until assuming no
987 routers are present.
988 Default: 3
989
990use_tempaddr - INTEGER
991 Preference for Privacy Extensions (RFC3041).
992 <= 0 : disable Privacy Extensions
993 == 1 : enable Privacy Extensions, but prefer public
994 addresses over temporary addresses.
995 > 1 : enable Privacy Extensions and prefer temporary
996 addresses over public addresses.
997 Default: 0 (for most devices)
998 -1 (for point-to-point devices and loopback devices)
999
1000temp_valid_lft - INTEGER
1001 valid lifetime (in seconds) for temporary addresses.
1002 Default: 604800 (7 days)
1003
1004temp_prefered_lft - INTEGER
1005 Preferred lifetime (in seconds) for temporary addresses.
1006 Default: 86400 (1 day)
1007
1008max_desync_factor - INTEGER
1009 Maximum value for DESYNC_FACTOR, which is a random value
1010 that ensures that clients don't synchronize with each
1011 other and generate new addresses at exactly the same time.
1012 value is in seconds.
1013 Default: 600
1014
1015regen_max_retry - INTEGER
1016 Number of attempts before give up attempting to generate
1017 valid temporary addresses.
1018 Default: 5
1019
1020max_addresses - INTEGER
1021 Number of maximum addresses per interface. 0 disables limitation.
1022 It is recommended not set too large value (or 0) because it would
1023 be too easy way to crash kernel to allow to create too much of
1024 autoconfigured addresses.
1025 Default: 16
1026
YOSHIFUJI Hideaki778d80b2008-06-28 14:17:11 +09001027disable_ipv6 - BOOLEAN
1028 Disable IPv6 operation.
1029 Default: FALSE (enable IPv6 operation)
1030
YOSHIFUJI Hideaki1b34be72008-06-28 14:18:38 +09001031accept_dad - INTEGER
1032 Whether to accept DAD (Duplicate Address Detection).
1033 0: Disable DAD
1034 1: Enable DAD (default)
1035 2: Enable DAD, and disable IPv6 operation if MAC-based duplicate
1036 link-local address has been found.
1037
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038icmp/*:
1039ratelimit - INTEGER
1040 Limit the maximal rates for sending ICMPv6 packets.
Stephen Hemminger6dbf4bc2008-07-01 19:29:07 -07001041 0 to disable any limiting,
1042 otherwise the minimal space between responses in milliseconds.
1043 Default: 1000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044
1045
1046IPv6 Update by:
1047Pekka Savola <pekkas@netcore.fi>
1048YOSHIFUJI Hideaki / USAGI Project <yoshfuji@linux-ipv6.org>
1049
1050
1051/proc/sys/net/bridge/* Variables:
1052
1053bridge-nf-call-arptables - BOOLEAN
1054 1 : pass bridged ARP traffic to arptables' FORWARD chain.
1055 0 : disable this.
1056 Default: 1
1057
1058bridge-nf-call-iptables - BOOLEAN
1059 1 : pass bridged IPv4 traffic to iptables' chains.
1060 0 : disable this.
1061 Default: 1
1062
1063bridge-nf-call-ip6tables - BOOLEAN
1064 1 : pass bridged IPv6 traffic to ip6tables' chains.
1065 0 : disable this.
1066 Default: 1
1067
1068bridge-nf-filter-vlan-tagged - BOOLEAN
Michael Milner516299d2007-04-12 22:14:23 -07001069 1 : pass bridged vlan-tagged ARP/IP/IPv6 traffic to {arp,ip,ip6}tables.
1070 0 : disable this.
1071 Default: 1
1072
1073bridge-nf-filter-pppoe-tagged - BOOLEAN
1074 1 : pass bridged pppoe-tagged IP/IPv6 traffic to {ip,ip6}tables.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 0 : disable this.
1076 Default: 1
1077
1078
Vlad Yasevich32e8d492008-07-08 16:43:29 -07001079proc/sys/net/sctp/* Variables:
1080
1081addip_enable - BOOLEAN
1082 Enable or disable extension of Dynamic Address Reconfiguration
1083 (ADD-IP) functionality specified in RFC5061. This extension provides
1084 the ability to dynamically add and remove new addresses for the SCTP
1085 associations.
1086
1087 1: Enable extension.
1088
1089 0: Disable extension.
1090
1091 Default: 0
1092
1093addip_noauth_enable - BOOLEAN
1094 Dynamic Address Reconfiguration (ADD-IP) requires the use of
1095 authentication to protect the operations of adding or removing new
1096 addresses. This requirement is mandated so that unauthorized hosts
1097 would not be able to hijack associations. However, older
1098 implementations may not have implemented this requirement while
1099 allowing the ADD-IP extension. For reasons of interoperability,
1100 we provide this variable to control the enforcement of the
1101 authentication requirement.
1102
1103 1: Allow ADD-IP extension to be used without authentication. This
1104 should only be set in a closed environment for interoperability
1105 with older implementations.
1106
1107 0: Enforce the authentication requirement
1108
1109 Default: 0
1110
1111auth_enable - BOOLEAN
1112 Enable or disable Authenticated Chunks extension. This extension
1113 provides the ability to send and receive authenticated chunks and is
1114 required for secure operation of Dynamic Address Reconfiguration
1115 (ADD-IP) extension.
1116
1117 1: Enable this extension.
1118 0: Disable this extension.
1119
1120 Default: 0
1121
1122prsctp_enable - BOOLEAN
1123 Enable or disable the Partial Reliability extension (RFC3758) which
1124 is used to notify peers that a given DATA should no longer be expected.
1125
1126 1: Enable extension
1127 0: Disable
1128
1129 Default: 1
1130
1131max_burst - INTEGER
1132 The limit of the number of new packets that can be initially sent. It
1133 controls how bursty the generated traffic can be.
1134
1135 Default: 4
1136
1137association_max_retrans - INTEGER
1138 Set the maximum number for retransmissions that an association can
1139 attempt deciding that the remote end is unreachable. If this value
1140 is exceeded, the association is terminated.
1141
1142 Default: 10
1143
1144max_init_retransmits - INTEGER
1145 The maximum number of retransmissions of INIT and COOKIE-ECHO chunks
1146 that an association will attempt before declaring the destination
1147 unreachable and terminating.
1148
1149 Default: 8
1150
1151path_max_retrans - INTEGER
1152 The maximum number of retransmissions that will be attempted on a given
1153 path. Once this threshold is exceeded, the path is considered
1154 unreachable, and new traffic will use a different path when the
1155 association is multihomed.
1156
1157 Default: 5
1158
1159rto_initial - INTEGER
1160 The initial round trip timeout value in milliseconds that will be used
1161 in calculating round trip times. This is the initial time interval
1162 for retransmissions.
1163
1164 Default: 3000
1165
1166rto_max - INTEGER
1167 The maximum value (in milliseconds) of the round trip timeout. This
1168 is the largest time interval that can elapse between retransmissions.
1169
1170 Default: 60000
1171
1172rto_min - INTEGER
1173 The minimum value (in milliseconds) of the round trip timeout. This
1174 is the smallest time interval the can elapse between retransmissions.
1175
1176 Default: 1000
1177
1178hb_interval - INTEGER
1179 The interval (in milliseconds) between HEARTBEAT chunks. These chunks
1180 are sent at the specified interval on idle paths to probe the state of
1181 a given path between 2 associations.
1182
1183 Default: 30000
1184
1185sack_timeout - INTEGER
1186 The amount of time (in milliseconds) that the implementation will wait
1187 to send a SACK.
1188
1189 Default: 200
1190
1191valid_cookie_life - INTEGER
1192 The default lifetime of the SCTP cookie (in milliseconds). The cookie
1193 is used during association establishment.
1194
1195 Default: 60000
1196
1197cookie_preserve_enable - BOOLEAN
1198 Enable or disable the ability to extend the lifetime of the SCTP cookie
1199 that is used during the establishment phase of SCTP association
1200
1201 1: Enable cookie lifetime extension.
1202 0: Disable
1203
1204 Default: 1
1205
1206rcvbuf_policy - INTEGER
1207 Determines if the receive buffer is attributed to the socket or to
1208 association. SCTP supports the capability to create multiple
1209 associations on a single socket. When using this capability, it is
1210 possible that a single stalled association that's buffering a lot
1211 of data may block other associations from delivering their data by
1212 consuming all of the receive buffer space. To work around this,
1213 the rcvbuf_policy could be set to attribute the receiver buffer space
1214 to each association instead of the socket. This prevents the described
1215 blocking.
1216
1217 1: rcvbuf space is per association
1218 0: recbuf space is per socket
1219
1220 Default: 0
1221
1222sndbuf_policy - INTEGER
1223 Similar to rcvbuf_policy above, this applies to send buffer space.
1224
1225 1: Send buffer is tracked per association
1226 0: Send buffer is tracked per socket.
1227
1228 Default: 0
1229
1230sctp_mem - vector of 3 INTEGERs: min, pressure, max
1231 Number of pages allowed for queueing by all SCTP sockets.
1232
1233 min: Below this number of pages SCTP is not bothered about its
1234 memory appetite. When amount of memory allocated by SCTP exceeds
1235 this number, SCTP starts to moderate memory usage.
1236
1237 pressure: This value was introduced to follow format of tcp_mem.
1238
1239 max: Number of pages allowed for queueing by all SCTP sockets.
1240
1241 Default is calculated at boot time from amount of available memory.
1242
1243sctp_rmem - vector of 3 INTEGERs: min, default, max
1244 See tcp_rmem for a description.
1245
1246sctp_wmem - vector of 3 INTEGERs: min, default, max
1247 See tcp_wmem for a description.
1248
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249UNDOCUMENTED:
1250
Stephen Hemminger4edc2f32008-07-10 16:50:26 -07001251/proc/sys/net/core/*
1252 dev_weight FIXME
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253
Stephen Hemminger4edc2f32008-07-10 16:50:26 -07001254/proc/sys/net/unix/*
1255 max_dgram_qlen FIXME
1256
1257/proc/sys/net/irda/*
1258 fast_poll_increase FIXME
1259 warn_noreply_time FIXME
1260 discovery_slots FIXME
1261 slot_timeout FIXME
1262 max_baud_rate FIXME
1263 discovery_timeout FIXME
1264 lap_keepalive_time FIXME
1265 max_noreply_time FIXME
1266 max_tx_data_size FIXME
1267 max_tx_window FIXME
1268 min_tx_turn_time FIXME