| blob | 26364d06ae927f0262e4cbccda03d1ad2cca35ba |
1 /proc/sys/net/ipv4/* Variables:
3 ip_forward - BOOLEAN
4 0 - disabled (default)
5 not 0 - enabled
7 Forward Packets between interfaces.
9 This variable is special, its change resets all configuration
10 parameters to their default state (RFC1122 for hosts, RFC1812
11 for routers)
13 ip_default_ttl - INTEGER
14 default 64
16 ip_no_pmtu_disc - BOOLEAN
17 Disable Path MTU Discovery.
18 default FALSE
20 min_pmtu - INTEGER
21 default 562 - minimum discovered Path MTU
23 mtu_expires - INTEGER
24 Time, in seconds, that cached PMTU information is kept.
26 min_adv_mss - INTEGER
27 The advertised MSS depends on the first hop route MTU, but will
28 never be lower than this setting.
30 IP Fragmentation:
32 ipfrag_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.
38 ipfrag_low_thresh - INTEGER
39 See ipfrag_high_thresh
41 ipfrag_time - INTEGER
42 Time in seconds to keep an IP fragment in memory.
44 ipfrag_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
49 ipfrag_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.
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
72 INET peer storage:
74 inet_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.
80 inet_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.
84 Measured in jiffies(1).
86 inet_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).
90 Measured in jiffies(1).
92 inet_peer_gc_mintime - INTEGER
93 Minimum interval between garbage collection passes. This interval is
94 in effect under high memory pressure on the pool.
95 Measured in jiffies(1).
97 inet_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.
100 Measured in jiffies(1).
102 TCP variables:
104 tcp_abc - INTEGER
105 Controls Appropriate Byte Count defined in RFC3465. If set to
106 0 then does congestion avoid once per ack. 1 is conservative
107 value, and 2 is more agressive.
109 tcp_syn_retries - INTEGER
110 Number of times initial SYNs for an active TCP connection attempt
111 will be retransmitted. Should not be higher than 255. Default value
112 is 5, which corresponds to ~180seconds.
114 tcp_synack_retries - INTEGER
115 Number of times SYNACKs for a passive TCP connection attempt will
116 be retransmitted. Should not be higher than 255. Default value
117 is 5, which corresponds to ~180seconds.
119 tcp_keepalive_time - INTEGER
120 How often TCP sends out keepalive messages when keepalive is enabled.
121 Default: 2hours.
123 tcp_keepalive_probes - INTEGER
124 How many keepalive probes TCP sends out, until it decides that the
125 connection is broken. Default value: 9.
127 tcp_keepalive_intvl - INTEGER
128 How frequently the probes are send out. Multiplied by
129 tcp_keepalive_probes it is time to kill not responding connection,
130 after probes started. Default value: 75sec i.e. connection
131 will be aborted after ~11 minutes of retries.
133 tcp_retries1 - INTEGER
134 How many times to retry before deciding that something is wrong
135 and it is necessary to report this suspicion to network layer.
136 Minimal RFC value is 3, it is default, which corresponds
137 to ~3sec-8min depending on RTO.
139 tcp_retries2 - INTEGER
140 How may times to retry before killing alive TCP connection.
141 RFC1122 says that the limit should be longer than 100 sec.
142 It is too small number. Default value 15 corresponds to ~13-30min
143 depending on RTO.
145 tcp_orphan_retries - INTEGER
146 How may times to retry before killing TCP connection, closed
147 by our side. Default value 7 corresponds to ~50sec-16min
148 depending on RTO. If you machine is loaded WEB server,
149 you should think about lowering this value, such sockets
150 may consume significant resources. Cf. tcp_max_orphans.
152 tcp_fin_timeout - INTEGER
153 Time to hold socket in state FIN-WAIT-2, if it was closed
154 by our side. Peer can be broken and never close its side,
155 or even died unexpectedly. Default value is 60sec.
156 Usual value used in 2.2 was 180 seconds, you may restore
157 it, but remember that if your machine is even underloaded WEB server,
158 you risk to overflow memory with kilotons of dead sockets,
159 FIN-WAIT-2 sockets are less dangerous than FIN-WAIT-1,
160 because they eat maximum 1.5K of memory, but they tend
161 to live longer. Cf. tcp_max_orphans.
163 tcp_max_tw_buckets - INTEGER
164 Maximal number of timewait sockets held by system simultaneously.
165 If this number is exceeded time-wait socket is immediately destroyed
166 and warning is printed. This limit exists only to prevent
167 simple DoS attacks, you _must_ not lower the limit artificially,
168 but rather increase it (probably, after increasing installed memory),
169 if network conditions require more than default value.
171 tcp_tw_recycle - BOOLEAN
172 Enable fast recycling TIME-WAIT sockets. Default value is 0.
173 It should not be changed without advice/request of technical
174 experts.
176 tcp_tw_reuse - BOOLEAN
177 Allow to reuse TIME-WAIT sockets for new connections when it is
178 safe from protocol viewpoint. Default value is 0.
179 It should not be changed without advice/request of technical
180 experts.
182 tcp_max_orphans - INTEGER
183 Maximal number of TCP sockets not attached to any user file handle,
184 held by system. If this number is exceeded orphaned connections are
185 reset immediately and warning is printed. This limit exists
186 only to prevent simple DoS attacks, you _must_ not rely on this
187 or lower the limit artificially, but rather increase it
188 (probably, after increasing installed memory),
189 if network conditions require more than default value,
190 and tune network services to linger and kill such states
191 more aggressively. Let me to remind again: each orphan eats
192 up to ~64K of unswappable memory.
194 tcp_abort_on_overflow - BOOLEAN
195 If listening service is too slow to accept new connections,
196 reset them. Default state is FALSE. It means that if overflow
197 occurred due to a burst, connection will recover. Enable this
198 option _only_ if you are really sure that listening daemon
199 cannot be tuned to accept connections faster. Enabling this
200 option can harm clients of your server.
202 tcp_syncookies - BOOLEAN
203 Only valid when the kernel was compiled with CONFIG_SYNCOOKIES
204 Send out syncookies when the syn backlog queue of a socket
205 overflows. This is to prevent against the common 'syn flood attack'
206 Default: FALSE
208 Note, that syncookies is fallback facility.
209 It MUST NOT be used to help highly loaded servers to stand
210 against legal connection rate. If you see synflood warnings
211 in your logs, but investigation shows that they occur
212 because of overload with legal connections, you should tune
213 another parameters until this warning disappear.
214 See: tcp_max_syn_backlog, tcp_synack_retries, tcp_abort_on_overflow.
216 syncookies seriously violate TCP protocol, do not allow
217 to use TCP extensions, can result in serious degradation
218 of some services (f.e. SMTP relaying), visible not by you,
219 but your clients and relays, contacting you. While you see
220 synflood warnings in logs not being really flooded, your server
221 is seriously misconfigured.
223 tcp_stdurg - BOOLEAN
224 Use the Host requirements interpretation of the TCP urg pointer field.
225 Most hosts use the older BSD interpretation, so if you turn this on
226 Linux might not communicate correctly with them.
227 Default: FALSE
229 tcp_max_syn_backlog - INTEGER
230 Maximal number of remembered connection requests, which are
231 still did not receive an acknowledgment from connecting client.
232 Default value is 1024 for systems with more than 128Mb of memory,
233 and 128 for low memory machines. If server suffers of overload,
234 try to increase this number.
236 tcp_window_scaling - BOOLEAN
237 Enable window scaling as defined in RFC1323.
239 tcp_timestamps - BOOLEAN
240 Enable timestamps as defined in RFC1323.
242 tcp_sack - BOOLEAN
243 Enable select acknowledgments (SACKS).
245 tcp_fack - BOOLEAN
246 Enable FACK congestion avoidance and fast retransmission.
247 The value is not used, if tcp_sack is not enabled.
249 tcp_dsack - BOOLEAN
250 Allows TCP to send "duplicate" SACKs.
252 tcp_ecn - BOOLEAN
253 Enable Explicit Congestion Notification in TCP.
255 tcp_reordering - INTEGER
256 Maximal reordering of packets in a TCP stream.
257 Default: 3
259 tcp_retrans_collapse - BOOLEAN
260 Bug-to-bug compatibility with some broken printers.
261 On retransmit try to send bigger packets to work around bugs in
262 certain TCP stacks.
264 tcp_wmem - vector of 3 INTEGERs: min, default, max
265 min: Amount of memory reserved for send buffers for TCP socket.
266 Each TCP socket has rights to use it due to fact of its birth.
267 Default: 4K
269 default: Amount of memory allowed for send buffers for TCP socket
270 by default. This value overrides net.core.wmem_default used
271 by other protocols, it is usually lower than net.core.wmem_default.
272 Default: 16K
274 max: Maximal amount of memory allowed for automatically selected
275 send buffers for TCP socket. This value does not override
276 net.core.wmem_max, "static" selection via SO_SNDBUF does not use this.
277 Default: 128K
279 tcp_rmem - vector of 3 INTEGERs: min, default, max
280 min: Minimal size of receive buffer used by TCP sockets.
281 It is guaranteed to each TCP socket, even under moderate memory
282 pressure.
283 Default: 8K
285 default: default size of receive buffer used by TCP sockets.
286 This value overrides net.core.rmem_default used by other protocols.
287 Default: 87380 bytes. This value results in window of 65535 with
288 default setting of tcp_adv_win_scale and tcp_app_win:0 and a bit
289 less for default tcp_app_win. See below about these variables.
291 max: maximal size of receive buffer allowed for automatically
292 selected receiver buffers for TCP socket. This value does not override
293 net.core.rmem_max, "static" selection via SO_RCVBUF does not use this.
294 Default: 87380*2 bytes.
296 tcp_mem - vector of 3 INTEGERs: min, pressure, max
297 low: below this number of pages TCP is not bothered about its
298 memory appetite.
300 pressure: when amount of memory allocated by TCP exceeds this number
301 of pages, TCP moderates its memory consumption and enters memory
302 pressure mode, which is exited when memory consumption falls
303 under "low".
305 high: number of pages allowed for queueing by all TCP sockets.
307 Defaults are calculated at boot time from amount of available
308 memory.
310 tcp_app_win - INTEGER
311 Reserve max(window/2^tcp_app_win, mss) of window for application
312 buffer. Value 0 is special, it means that nothing is reserved.
313 Default: 31
315 tcp_adv_win_scale - INTEGER
316 Count buffering overhead as bytes/2^tcp_adv_win_scale
317 (if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale),
318 if it is <= 0.
319 Default: 2
321 tcp_rfc1337 - BOOLEAN
322 If set, the TCP stack behaves conforming to RFC1337. If unset,
323 we are not conforming to RFC, but prevent TCP TIME_WAIT
324 assassination.
325 Default: 0
327 tcp_low_latency - BOOLEAN
328 If set, the TCP stack makes decisions that prefer lower
329 latency as opposed to higher throughput. By default, this
330 option is not set meaning that higher throughput is preferred.
331 An example of an application where this default should be
332 changed would be a Beowulf compute cluster.
333 Default: 0
335 tcp_tso_win_divisor - INTEGER
336 This allows control over what percentage of the congestion window
337 can be consumed by a single TSO frame.
338 The setting of this parameter is a choice between burstiness and
339 building larger TSO frames.
340 Default: 3
342 tcp_frto - BOOLEAN
343 Enables F-RTO, an enhanced recovery algorithm for TCP retransmission
344 timeouts. It is particularly beneficial in wireless environments
345 where packet loss is typically due to random radio interference
346 rather than intermediate router congestion.
348 tcp_congestion_control - STRING
349 Set the congestion control algorithm to be used for new
350 connections. The algorithm "reno" is always available, but
351 additional choices may be available based on kernel configuration.
353 somaxconn - INTEGER
354 Limit of socket listen() backlog, known in userspace as SOMAXCONN.
355 Defaults to 128. See also tcp_max_syn_backlog for additional tuning
356 for TCP sockets.
358 IP Variables:
360 ip_local_port_range - 2 INTEGERS
361 Defines the local port range that is used by TCP and UDP to
362 choose the local port. The first number is the first, the
363 second the last local port number. Default value depends on
364 amount of memory available on the system:
365 > 128Mb 32768-61000
366 < 128Mb 1024-4999 or even less.
367 This number defines number of active connections, which this
368 system can issue simultaneously to systems not supporting
369 TCP extensions (timestamps). With tcp_tw_recycle enabled
370 (i.e. by default) range 1024-4999 is enough to issue up to
371 2000 connections per second to systems supporting timestamps.
373 ip_nonlocal_bind - BOOLEAN
374 If set, allows processes to bind() to non-local IP addresses,
375 which can be quite useful - but may break some applications.
376 Default: 0
378 ip_dynaddr - BOOLEAN
379 If set non-zero, enables support for dynamic addresses.
380 If set to a non-zero value larger than 1, a kernel log
381 message will be printed when dynamic address rewriting
382 occurs.
383 Default: 0
385 icmp_echo_ignore_all - BOOLEAN
386 If set non-zero, then the kernel will ignore all ICMP ECHO
387 requests sent to it.
388 Default: 0
390 icmp_echo_ignore_broadcasts - BOOLEAN
391 If set non-zero, then the kernel will ignore all ICMP ECHO and
392 TIMESTAMP requests sent to it via broadcast/multicast.
393 Default: 1
395 icmp_ratelimit - INTEGER
396 Limit the maximal rates for sending ICMP packets whose type matches
397 icmp_ratemask (see below) to specific targets.
398 0 to disable any limiting, otherwise the maximal rate in jiffies(1)
399 Default: 100
401 icmp_ratemask - INTEGER
402 Mask made of ICMP types for which rates are being limited.
403 Significant bits: IHGFEDCBA9876543210
404 Default mask: 0000001100000011000 (6168)
406 Bit definitions (see include/linux/icmp.h):
407 0 Echo Reply
408 3 Destination Unreachable *
409 4 Source Quench *
410 5 Redirect
411 8 Echo Request
412 B Time Exceeded *
413 C Parameter Problem *
414 D Timestamp Request
415 E Timestamp Reply
416 F Info Request
417 G Info Reply
418 H Address Mask Request
419 I Address Mask Reply
421 * These are rate limited by default (see default mask above)
423 icmp_ignore_bogus_error_responses - BOOLEAN
424 Some routers violate RFC1122 by sending bogus responses to broadcast
425 frames. Such violations are normally logged via a kernel warning.
426 If this is set to TRUE, the kernel will not give such warnings, which
427 will avoid log file clutter.
428 Default: FALSE
430 icmp_errors_use_inbound_ifaddr - BOOLEAN
432 If zero, icmp error messages are sent with the primary address of
433 the exiting interface.
435 If non-zero, the message will be sent with the primary address of
436 the interface that received the packet that caused the icmp error.
437 This is the behaviour network many administrators will expect from
438 a router. And it can make debugging complicated network layouts
439 much easier.
441 Note that if no primary address exists for the interface selected,
442 then the primary address of the first non-loopback interface that
443 has one will be used regarldess of this setting.
445 Default: 0
447 igmp_max_memberships - INTEGER
448 Change the maximum number of multicast groups we can subscribe to.
449 Default: 20
451 conf/interface/* changes special settings per interface (where "interface" is
452 the name of your network interface)
453 conf/all/* is special, changes the settings for all interfaces
456 log_martians - BOOLEAN
457 Log packets with impossible addresses to kernel log.
458 log_martians for the interface will be enabled if at least one of
459 conf/{all,interface}/log_martians is set to TRUE,
460 it will be disabled otherwise
462 accept_redirects - BOOLEAN
463 Accept ICMP redirect messages.
464 accept_redirects for the interface will be enabled if:
465 - both conf/{all,interface}/accept_redirects are TRUE in the case forwarding
466 for the interface is enabled
467 or
468 - at least one of conf/{all,interface}/accept_redirects is TRUE in the case
469 forwarding for the interface is disabled
470 accept_redirects for the interface will be disabled otherwise
471 default TRUE (host)
472 FALSE (router)
474 forwarding - BOOLEAN
475 Enable IP forwarding on this interface.
477 mc_forwarding - BOOLEAN
478 Do multicast routing. The kernel needs to be compiled with CONFIG_MROUTE
479 and a multicast routing daemon is required.
480 conf/all/mc_forwarding must also be set to TRUE to enable multicast routing
481 for the interface
483 medium_id - INTEGER
484 Integer value used to differentiate the devices by the medium they
485 are attached to. Two devices can have different id values when
486 the broadcast packets are received only on one of them.
487 The default value 0 means that the device is the only interface
488 to its medium, value of -1 means that medium is not known.
490 Currently, it is used to change the proxy_arp behavior:
491 the proxy_arp feature is enabled for packets forwarded between
492 two devices attached to different media.
494 proxy_arp - BOOLEAN
495 Do proxy arp.
496 proxy_arp for the interface will be enabled if at least one of
497 conf/{all,interface}/proxy_arp is set to TRUE,
498 it will be disabled otherwise
500 shared_media - BOOLEAN
501 Send(router) or accept(host) RFC1620 shared media redirects.
502 Overrides ip_secure_redirects.
503 shared_media for the interface will be enabled if at least one of
504 conf/{all,interface}/shared_media is set to TRUE,
505 it will be disabled otherwise
506 default TRUE
508 secure_redirects - BOOLEAN
509 Accept ICMP redirect messages only for gateways,
510 listed in default gateway list.
511 secure_redirects for the interface will be enabled if at least one of
512 conf/{all,interface}/secure_redirects is set to TRUE,
513 it will be disabled otherwise
514 default TRUE
516 send_redirects - BOOLEAN
517 Send redirects, if router.
518 send_redirects for the interface will be enabled if at least one of
519 conf/{all,interface}/send_redirects is set to TRUE,
520 it will be disabled otherwise
521 Default: TRUE
523 bootp_relay - BOOLEAN
524 Accept packets with source address 0.b.c.d destined
525 not to this host as local ones. It is supposed, that
526 BOOTP relay daemon will catch and forward such packets.
527 conf/all/bootp_relay must also be set to TRUE to enable BOOTP relay
528 for the interface
529 default FALSE
530 Not Implemented Yet.
532 accept_source_route - BOOLEAN
533 Accept packets with SRR option.
534 conf/all/accept_source_route must also be set to TRUE to accept packets
535 with SRR option on the interface
536 default TRUE (router)
537 FALSE (host)
539 rp_filter - BOOLEAN
540 1 - do source validation by reversed path, as specified in RFC1812
541 Recommended option for single homed hosts and stub network
542 routers. Could cause troubles for complicated (not loop free)
543 networks running a slow unreliable protocol (sort of RIP),
544 or using static routes.
546 0 - No source validation.
548 conf/all/rp_filter must also be set to TRUE to do source validation
549 on the interface
551 Default value is 0. Note that some distributions enable it
552 in startup scripts.
554 arp_filter - BOOLEAN
555 1 - Allows you to have multiple network interfaces on the same
556 subnet, and have the ARPs for each interface be answered
557 based on whether or not the kernel would route a packet from
558 the ARP'd IP out that interface (therefore you must use source
559 based routing for this to work). In other words it allows control
560 of which cards (usually 1) will respond to an arp request.
562 0 - (default) The kernel can respond to arp requests with addresses
563 from other interfaces. This may seem wrong but it usually makes
564 sense, because it increases the chance of successful communication.
565 IP addresses are owned by the complete host on Linux, not by
566 particular interfaces. Only for more complex setups like load-
567 balancing, does this behaviour cause problems.
569 arp_filter for the interface will be enabled if at least one of
570 conf/{all,interface}/arp_filter is set to TRUE,
571 it will be disabled otherwise
573 arp_announce - INTEGER
574 Define different restriction levels for announcing the local
575 source IP address from IP packets in ARP requests sent on
576 interface:
577 0 - (default) Use any local address, configured on any interface
578 1 - Try to avoid local addresses that are not in the target's
579 subnet for this interface. This mode is useful when target
580 hosts reachable via this interface require the source IP
581 address in ARP requests to be part of their logical network
582 configured on the receiving interface. When we generate the
583 request we will check all our subnets that include the
584 target IP and will preserve the source address if it is from
585 such subnet. If there is no such subnet we select source
586 address according to the rules for level 2.
587 2 - Always use the best local address for this target.
588 In this mode we ignore the source address in the IP packet
589 and try to select local address that we prefer for talks with
590 the target host. Such local address is selected by looking
591 for primary IP addresses on all our subnets on the outgoing
592 interface that include the target IP address. If no suitable
593 local address is found we select the first local address
594 we have on the outgoing interface or on all other interfaces,
595 with the hope we will receive reply for our request and
596 even sometimes no matter the source IP address we announce.
598 The max value from conf/{all,interface}/arp_announce is used.
600 Increasing the restriction level gives more chance for
601 receiving answer from the resolved target while decreasing
602 the level announces more valid sender's information.
604 arp_ignore - INTEGER
605 Define different modes for sending replies in response to
606 received ARP requests that resolve local target IP addresses:
607 0 - (default): reply for any local target IP address, configured
608 on any interface
609 1 - reply only if the target IP address is local address
610 configured on the incoming interface
611 2 - reply only if the target IP address is local address
612 configured on the incoming interface and both with the
613 sender's IP address are part from same subnet on this interface
614 3 - do not reply for local addresses configured with scope host,
615 only resolutions for global and link addresses are replied
616 4-7 - reserved
617 8 - do not reply for all local addresses
619 The max value from conf/{all,interface}/arp_ignore is used
620 when ARP request is received on the {interface}
622 app_solicit - INTEGER
623 The maximum number of probes to send to the user space ARP daemon
624 via netlink before dropping back to multicast probes (see
625 mcast_solicit). Defaults to 0.
627 disable_policy - BOOLEAN
628 Disable IPSEC policy (SPD) for this interface
630 disable_xfrm - BOOLEAN
631 Disable IPSEC encryption on this interface, whatever the policy
635 tag - INTEGER
636 Allows you to write a number, which can be used as required.
637 Default value is 0.
639 (1) Jiffie: internal timeunit for the kernel. On the i386 1/100s, on the
640 Alpha 1/1024s. See the HZ define in /usr/include/asm/param.h for the exact
641 value on your system.
643 Alexey Kuznetsov.
644 kuznet@ms2.inr.ac.ru
646 Updated by:
647 Andi Kleen
648 ak@muc.de
649 Nicolas Delon
650 delon.nicolas@wanadoo.fr
655 /proc/sys/net/ipv6/* Variables:
657 IPv6 has no global variables such as tcp_*. tcp_* settings under ipv4/ also
658 apply to IPv6 [XXX?].
660 bindv6only - BOOLEAN
661 Default value for IPV6_V6ONLY socket option,
662 which restricts use of the IPv6 socket to IPv6 communication
663 only.
664 TRUE: disable IPv4-mapped address feature
665 FALSE: enable IPv4-mapped address feature
667 Default: FALSE (as specified in RFC2553bis)
669 IPv6 Fragmentation:
671 ip6frag_high_thresh - INTEGER
672 Maximum memory used to reassemble IPv6 fragments. When
673 ip6frag_high_thresh bytes of memory is allocated for this purpose,
674 the fragment handler will toss packets until ip6frag_low_thresh
675 is reached.
677 ip6frag_low_thresh - INTEGER
678 See ip6frag_high_thresh
680 ip6frag_time - INTEGER
681 Time in seconds to keep an IPv6 fragment in memory.
683 ip6frag_secret_interval - INTEGER
684 Regeneration interval (in seconds) of the hash secret (or lifetime
685 for the hash secret) for IPv6 fragments.
686 Default: 600
688 conf/default/*:
689 Change the interface-specific default settings.
692 conf/all/*:
693 Change all the interface-specific settings.
695 [XXX: Other special features than forwarding?]
697 conf/all/forwarding - BOOLEAN
698 Enable global IPv6 forwarding between all interfaces.
700 IPv4 and IPv6 work differently here; e.g. netfilter must be used
701 to control which interfaces may forward packets and which not.
703 This also sets all interfaces' Host/Router setting
704 'forwarding' to the specified value. See below for details.
706 This referred to as global forwarding.
708 conf/interface/*:
709 Change special settings per interface.
711 The functional behaviour for certain settings is different
712 depending on whether local forwarding is enabled or not.
714 accept_ra - BOOLEAN
715 Accept Router Advertisements; autoconfigure using them.
717 Functional default: enabled if local forwarding is disabled.
718 disabled if local forwarding is enabled.
720 accept_redirects - BOOLEAN
721 Accept Redirects.
723 Functional default: enabled if local forwarding is disabled.
724 disabled if local forwarding is enabled.
726 autoconf - BOOLEAN
727 Autoconfigure addresses using Prefix Information in Router
728 Advertisements.
730 Functional default: enabled if accept_ra is enabled.
731 disabled if accept_ra is disabled.
733 dad_transmits - INTEGER
734 The amount of Duplicate Address Detection probes to send.
735 Default: 1
737 forwarding - BOOLEAN
738 Configure interface-specific Host/Router behaviour.
740 Note: It is recommended to have the same setting on all
741 interfaces; mixed router/host scenarios are rather uncommon.
743 FALSE:
745 By default, Host behaviour is assumed. This means:
747 1. IsRouter flag is not set in Neighbour Advertisements.
748 2. Router Solicitations are being sent when necessary.
749 3. If accept_ra is TRUE (default), accept Router
750 Advertisements (and do autoconfiguration).
751 4. If accept_redirects is TRUE (default), accept Redirects.
753 TRUE:
755 If local forwarding is enabled, Router behaviour is assumed.
756 This means exactly the reverse from the above:
758 1. IsRouter flag is set in Neighbour Advertisements.
759 2. Router Solicitations are not sent.
760 3. Router Advertisements are ignored.
761 4. Redirects are ignored.
763 Default: FALSE if global forwarding is disabled (default),
764 otherwise TRUE.
766 hop_limit - INTEGER
767 Default Hop Limit to set.
768 Default: 64
770 mtu - INTEGER
771 Default Maximum Transfer Unit
772 Default: 1280 (IPv6 required minimum)
774 router_solicitation_delay - INTEGER
775 Number of seconds to wait after interface is brought up
776 before sending Router Solicitations.
777 Default: 1
779 router_solicitation_interval - INTEGER
780 Number of seconds to wait between Router Solicitations.
781 Default: 4
783 router_solicitations - INTEGER
784 Number of Router Solicitations to send until assuming no
785 routers are present.
786 Default: 3
788 use_tempaddr - INTEGER
789 Preference for Privacy Extensions (RFC3041).
790 <= 0 : disable Privacy Extensions
791 == 1 : enable Privacy Extensions, but prefer public
792 addresses over temporary addresses.
793 > 1 : enable Privacy Extensions and prefer temporary
794 addresses over public addresses.
795 Default: 0 (for most devices)
796 -1 (for point-to-point devices and loopback devices)
798 temp_valid_lft - INTEGER
799 valid lifetime (in seconds) for temporary addresses.
800 Default: 604800 (7 days)
802 temp_prefered_lft - INTEGER
803 Preferred lifetime (in seconds) for temporary addresses.
804 Default: 86400 (1 day)
806 max_desync_factor - INTEGER
807 Maximum value for DESYNC_FACTOR, which is a random value
808 that ensures that clients don't synchronize with each
809 other and generate new addresses at exactly the same time.
810 value is in seconds.
811 Default: 600
813 regen_max_retry - INTEGER
814 Number of attempts before give up attempting to generate
815 valid temporary addresses.
816 Default: 5
818 max_addresses - INTEGER
819 Number of maximum addresses per interface. 0 disables limitation.
820 It is recommended not set too large value (or 0) because it would
821 be too easy way to crash kernel to allow to create too much of
822 autoconfigured addresses.
823 Default: 16
825 icmp/*:
826 ratelimit - INTEGER
827 Limit the maximal rates for sending ICMPv6 packets.
828 0 to disable any limiting, otherwise the maximal rate in jiffies(1)
829 Default: 100
832 IPv6 Update by:
833 Pekka Savola <pekkas@netcore.fi>
834 YOSHIFUJI Hideaki / USAGI Project <yoshfuji@linux-ipv6.org>
837 /proc/sys/net/bridge/* Variables:
839 bridge-nf-call-arptables - BOOLEAN
840 1 : pass bridged ARP traffic to arptables' FORWARD chain.
841 0 : disable this.
842 Default: 1
844 bridge-nf-call-iptables - BOOLEAN
845 1 : pass bridged IPv4 traffic to iptables' chains.
846 0 : disable this.
847 Default: 1
849 bridge-nf-call-ip6tables - BOOLEAN
850 1 : pass bridged IPv6 traffic to ip6tables' chains.
851 0 : disable this.
852 Default: 1
854 bridge-nf-filter-vlan-tagged - BOOLEAN
855 1 : pass bridged vlan-tagged ARP/IP traffic to arptables/iptables.
856 0 : disable this.
857 Default: 1
860 UNDOCUMENTED:
862 dev_weight FIXME
863 discovery_slots FIXME
864 discovery_timeout FIXME
865 fast_poll_increase FIXME
866 ip6_queue_maxlen FIXME
867 lap_keepalive_time FIXME
868 lo_cong FIXME
869 max_baud_rate FIXME
870 max_dgram_qlen FIXME
871 max_noreply_time FIXME
872 max_tx_data_size FIXME
873 max_tx_window FIXME
874 min_tx_turn_time FIXME
875 mod_cong FIXME
876 no_cong FIXME
877 no_cong_thresh FIXME
878 slot_timeout FIXME
879 warn_noreply_time FIXME
881 $Id: ip-sysctl.txt,v 1.20 2001/12/13 09:00:18 davem Exp $