1 /proc/sys/net/ipv4/* Variables:
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
13 ip_default_ttl - INTEGER
16 ip_no_pmtu_disc - BOOLEAN
17 Disable Path MTU Discovery.
21 default 562 - minimum discovered Path MTU
24 Time, in seconds, that cached PMTU information is kept.
27 The advertised MSS depends on the first hop route MTU, but will
28 never be lower than this setting.
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
38 ipfrag_low_thresh - INTEGER
39 See ipfrag_high_thresh
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.
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.
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).
105 Controls Appropriate Byte Count (ABC) defined in RFC3465.
106 ABC is a way of increasing congestion window (cwnd) more slowly
107 in response to partial acknowledgments.
109 0 increase cwnd once per acknowledgment (no ABC)
110 1 increase cwnd once per acknowledgment of full sized segment
111 2 allow increase cwnd by two if acknowledgment is
112 of two segments to compensate for delayed acknowledgments.
115 tcp_syn_retries - INTEGER
116 Number of times initial SYNs for an active TCP connection attempt
117 will be retransmitted. Should not be higher than 255. Default value
118 is 5, which corresponds to ~180seconds.
120 tcp_synack_retries - INTEGER
121 Number of times SYNACKs for a passive TCP connection attempt will
122 be retransmitted. Should not be higher than 255. Default value
123 is 5, which corresponds to ~180seconds.
125 tcp_keepalive_time - INTEGER
126 How often TCP sends out keepalive messages when keepalive is enabled.
129 tcp_keepalive_probes - INTEGER
130 How many keepalive probes TCP sends out, until it decides that the
131 connection is broken. Default value: 9.
133 tcp_keepalive_intvl - INTEGER
134 How frequently the probes are send out. Multiplied by
135 tcp_keepalive_probes it is time to kill not responding connection,
136 after probes started. Default value: 75sec i.e. connection
137 will be aborted after ~11 minutes of retries.
139 tcp_retries1 - INTEGER
140 How many times to retry before deciding that something is wrong
141 and it is necessary to report this suspicion to network layer.
142 Minimal RFC value is 3, it is default, which corresponds
143 to ~3sec-8min depending on RTO.
145 tcp_retries2 - INTEGER
146 How may times to retry before killing alive TCP connection.
147 RFC1122 says that the limit should be longer than 100 sec.
148 It is too small number. Default value 15 corresponds to ~13-30min
151 tcp_orphan_retries - INTEGER
152 How may times to retry before killing TCP connection, closed
153 by our side. Default value 7 corresponds to ~50sec-16min
154 depending on RTO. If you machine is loaded WEB server,
155 you should think about lowering this value, such sockets
156 may consume significant resources. Cf. tcp_max_orphans.
158 tcp_fin_timeout - INTEGER
159 Time to hold socket in state FIN-WAIT-2, if it was closed
160 by our side. Peer can be broken and never close its side,
161 or even died unexpectedly. Default value is 60sec.
162 Usual value used in 2.2 was 180 seconds, you may restore
163 it, but remember that if your machine is even underloaded WEB server,
164 you risk to overflow memory with kilotons of dead sockets,
165 FIN-WAIT-2 sockets are less dangerous than FIN-WAIT-1,
166 because they eat maximum 1.5K of memory, but they tend
167 to live longer. Cf. tcp_max_orphans.
169 tcp_max_tw_buckets - INTEGER
170 Maximal number of timewait sockets held by system simultaneously.
171 If this number is exceeded time-wait socket is immediately destroyed
172 and warning is printed. This limit exists only to prevent
173 simple DoS attacks, you _must_ not lower the limit artificially,
174 but rather increase it (probably, after increasing installed memory),
175 if network conditions require more than default value.
177 tcp_tw_recycle - BOOLEAN
178 Enable fast recycling TIME-WAIT sockets. Default value is 0.
179 It should not be changed without advice/request of technical
182 tcp_tw_reuse - BOOLEAN
183 Allow to reuse TIME-WAIT sockets for new connections when it is
184 safe from protocol viewpoint. Default value is 0.
185 It should not be changed without advice/request of technical
188 tcp_max_orphans - INTEGER
189 Maximal number of TCP sockets not attached to any user file handle,
190 held by system. If this number is exceeded orphaned connections are
191 reset immediately and warning is printed. This limit exists
192 only to prevent simple DoS attacks, you _must_ not rely on this
193 or lower the limit artificially, but rather increase it
194 (probably, after increasing installed memory),
195 if network conditions require more than default value,
196 and tune network services to linger and kill such states
197 more aggressively. Let me to remind again: each orphan eats
198 up to ~64K of unswappable memory.
200 tcp_abort_on_overflow - BOOLEAN
201 If listening service is too slow to accept new connections,
202 reset them. Default state is FALSE. It means that if overflow
203 occurred due to a burst, connection will recover. Enable this
204 option _only_ if you are really sure that listening daemon
205 cannot be tuned to accept connections faster. Enabling this
206 option can harm clients of your server.
208 tcp_syncookies - BOOLEAN
209 Only valid when the kernel was compiled with CONFIG_SYNCOOKIES
210 Send out syncookies when the syn backlog queue of a socket
211 overflows. This is to prevent against the common 'syn flood attack'
214 Note, that syncookies is fallback facility.
215 It MUST NOT be used to help highly loaded servers to stand
216 against legal connection rate. If you see synflood warnings
217 in your logs, but investigation shows that they occur
218 because of overload with legal connections, you should tune
219 another parameters until this warning disappear.
220 See: tcp_max_syn_backlog, tcp_synack_retries, tcp_abort_on_overflow.
222 syncookies seriously violate TCP protocol, do not allow
223 to use TCP extensions, can result in serious degradation
224 of some services (f.e. SMTP relaying), visible not by you,
225 but your clients and relays, contacting you. While you see
226 synflood warnings in logs not being really flooded, your server
227 is seriously misconfigured.
230 Use the Host requirements interpretation of the TCP urg pointer field.
231 Most hosts use the older BSD interpretation, so if you turn this on
232 Linux might not communicate correctly with them.
235 tcp_max_syn_backlog - INTEGER
236 Maximal number of remembered connection requests, which are
237 still did not receive an acknowledgment from connecting client.
238 Default value is 1024 for systems with more than 128Mb of memory,
239 and 128 for low memory machines. If server suffers of overload,
240 try to increase this number.
242 tcp_window_scaling - BOOLEAN
243 Enable window scaling as defined in RFC1323.
245 tcp_timestamps - BOOLEAN
246 Enable timestamps as defined in RFC1323.
249 Enable select acknowledgments (SACKS).
252 Enable FACK congestion avoidance and fast retransmission.
253 The value is not used, if tcp_sack is not enabled.
256 Allows TCP to send "duplicate" SACKs.
259 Enable Explicit Congestion Notification in TCP.
261 tcp_reordering - INTEGER
262 Maximal reordering of packets in a TCP stream.
265 tcp_retrans_collapse - BOOLEAN
266 Bug-to-bug compatibility with some broken printers.
267 On retransmit try to send bigger packets to work around bugs in
270 tcp_wmem - vector of 3 INTEGERs: min, default, max
271 min: Amount of memory reserved for send buffers for TCP socket.
272 Each TCP socket has rights to use it due to fact of its birth.
275 default: Amount of memory allowed for send buffers for TCP socket
276 by default. This value overrides net.core.wmem_default used
277 by other protocols, it is usually lower than net.core.wmem_default.
280 max: Maximal amount of memory allowed for automatically selected
281 send buffers for TCP socket. This value does not override
282 net.core.wmem_max, "static" selection via SO_SNDBUF does not use this.
285 tcp_rmem - vector of 3 INTEGERs: min, default, max
286 min: Minimal size of receive buffer used by TCP sockets.
287 It is guaranteed to each TCP socket, even under moderate memory
291 default: default size of receive buffer used by TCP sockets.
292 This value overrides net.core.rmem_default used by other protocols.
293 Default: 87380 bytes. This value results in window of 65535 with
294 default setting of tcp_adv_win_scale and tcp_app_win:0 and a bit
295 less for default tcp_app_win. See below about these variables.
297 max: maximal size of receive buffer allowed for automatically
298 selected receiver buffers for TCP socket. This value does not override
299 net.core.rmem_max, "static" selection via SO_RCVBUF does not use this.
300 Default: 87380*2 bytes.
302 tcp_mem - vector of 3 INTEGERs: min, pressure, max
303 min: below this number of pages TCP is not bothered about its
306 pressure: when amount of memory allocated by TCP exceeds this number
307 of pages, TCP moderates its memory consumption and enters memory
308 pressure mode, which is exited when memory consumption falls
311 max: number of pages allowed for queueing by all TCP sockets.
313 Defaults are calculated at boot time from amount of available
316 tcp_app_win - INTEGER
317 Reserve max(window/2^tcp_app_win, mss) of window for application
318 buffer. Value 0 is special, it means that nothing is reserved.
321 tcp_adv_win_scale - INTEGER
322 Count buffering overhead as bytes/2^tcp_adv_win_scale
323 (if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale),
327 tcp_rfc1337 - BOOLEAN
328 If set, the TCP stack behaves conforming to RFC1337. If unset,
329 we are not conforming to RFC, but prevent TCP TIME_WAIT
333 tcp_low_latency - BOOLEAN
334 If set, the TCP stack makes decisions that prefer lower
335 latency as opposed to higher throughput. By default, this
336 option is not set meaning that higher throughput is preferred.
337 An example of an application where this default should be
338 changed would be a Beowulf compute cluster.
341 tcp_tso_win_divisor - INTEGER
342 This allows control over what percentage of the congestion window
343 can be consumed by a single TSO frame.
344 The setting of this parameter is a choice between burstiness and
345 building larger TSO frames.
349 Enables F-RTO, an enhanced recovery algorithm for TCP retransmission
350 timeouts. It is particularly beneficial in wireless environments
351 where packet loss is typically due to random radio interference
352 rather than intermediate router congestion.
354 tcp_available_congestion_control - STRING
355 Shows the available congestion control choices that are registered.
356 More congestion control algorithms may be available as modules,
359 tcp_congestion_control - STRING
360 Set the congestion control algorithm to be used for new
361 connections. The algorithm "reno" is always available, but
362 additional choices may be available based on kernel configuration.
363 Default is set as part of kernel configuration.
366 Limit of socket listen() backlog, known in userspace as SOMAXCONN.
367 Defaults to 128. See also tcp_max_syn_backlog for additional tuning
370 tcp_workaround_signed_windows - BOOLEAN
371 If set, assume no receipt of a window scaling option means the
372 remote TCP is broken and treats the window as a signed quantity.
373 If unset, assume the remote TCP is not broken even if we do
374 not receive a window scaling option from them.
377 tcp_slow_start_after_idle - BOOLEAN
378 If set, provide RFC2861 behavior and time out the congestion
379 window after an idle period. An idle period is defined at
380 the current RTO. If unset, the congestion window will not
381 be timed out after an idle period.
386 cipso_cache_enable - BOOLEAN
387 If set, enable additions to and lookups from the CIPSO label mapping
388 cache. If unset, additions are ignored and lookups always result in a
389 miss. However, regardless of the setting the cache is still
390 invalidated when required when means you can safely toggle this on and
391 off and the cache will always be "safe".
394 cipso_cache_bucket_size - INTEGER
395 The CIPSO label cache consists of a fixed size hash table with each
396 hash bucket containing a number of cache entries. This variable limits
397 the number of entries in each hash bucket; the larger the value the
398 more CIPSO label mappings that can be cached. When the number of
399 entries in a given hash bucket reaches this limit adding new entries
400 causes the oldest entry in the bucket to be removed to make room.
403 cipso_rbm_optfmt - BOOLEAN
404 Enable the "Optimized Tag 1 Format" as defined in section 3.4.2.6 of
405 the CIPSO draft specification (see Documentation/netlabel for details).
406 This means that when set the CIPSO tag will be padded with empty
407 categories in order to make the packet data 32-bit aligned.
410 cipso_rbm_structvalid - BOOLEAN
411 If set, do a very strict check of the CIPSO option when
412 ip_options_compile() is called. If unset, relax the checks done during
413 ip_options_compile(). Either way is "safe" as errors are caught else
414 where in the CIPSO processing code but setting this to 0 (False) should
415 result in less work (i.e. it should be faster) but could cause problems
416 with other implementations that require strict checking.
421 ip_local_port_range - 2 INTEGERS
422 Defines the local port range that is used by TCP and UDP to
423 choose the local port. The first number is the first, the
424 second the last local port number. Default value depends on
425 amount of memory available on the system:
427 < 128Mb 1024-4999 or even less.
428 This number defines number of active connections, which this
429 system can issue simultaneously to systems not supporting
430 TCP extensions (timestamps). With tcp_tw_recycle enabled
431 (i.e. by default) range 1024-4999 is enough to issue up to
432 2000 connections per second to systems supporting timestamps.
434 ip_nonlocal_bind - BOOLEAN
435 If set, allows processes to bind() to non-local IP addresses,
436 which can be quite useful - but may break some applications.
440 If set non-zero, enables support for dynamic addresses.
441 If set to a non-zero value larger than 1, a kernel log
442 message will be printed when dynamic address rewriting
446 icmp_echo_ignore_all - BOOLEAN
447 If set non-zero, then the kernel will ignore all ICMP ECHO
451 icmp_echo_ignore_broadcasts - BOOLEAN
452 If set non-zero, then the kernel will ignore all ICMP ECHO and
453 TIMESTAMP requests sent to it via broadcast/multicast.
456 icmp_ratelimit - INTEGER
457 Limit the maximal rates for sending ICMP packets whose type matches
458 icmp_ratemask (see below) to specific targets.
459 0 to disable any limiting, otherwise the maximal rate in jiffies(1)
462 icmp_ratemask - INTEGER
463 Mask made of ICMP types for which rates are being limited.
464 Significant bits: IHGFEDCBA9876543210
465 Default mask: 0000001100000011000 (6168)
467 Bit definitions (see include/linux/icmp.h):
469 3 Destination Unreachable *
474 C Parameter Problem *
479 H Address Mask Request
482 * These are rate limited by default (see default mask above)
484 icmp_ignore_bogus_error_responses - BOOLEAN
485 Some routers violate RFC1122 by sending bogus responses to broadcast
486 frames. Such violations are normally logged via a kernel warning.
487 If this is set to TRUE, the kernel will not give such warnings, which
488 will avoid log file clutter.
491 icmp_errors_use_inbound_ifaddr - BOOLEAN
493 If zero, icmp error messages are sent with the primary address of
494 the exiting interface.
496 If non-zero, the message will be sent with the primary address of
497 the interface that received the packet that caused the icmp error.
498 This is the behaviour network many administrators will expect from
499 a router. And it can make debugging complicated network layouts
502 Note that if no primary address exists for the interface selected,
503 then the primary address of the first non-loopback interface that
504 has one will be used regardless of this setting.
508 igmp_max_memberships - INTEGER
509 Change the maximum number of multicast groups we can subscribe to.
512 conf/interface/* changes special settings per interface (where "interface" is
513 the name of your network interface)
514 conf/all/* is special, changes the settings for all interfaces
517 log_martians - BOOLEAN
518 Log packets with impossible addresses to kernel log.
519 log_martians for the interface will be enabled if at least one of
520 conf/{all,interface}/log_martians is set to TRUE,
521 it will be disabled otherwise
523 accept_redirects - BOOLEAN
524 Accept ICMP redirect messages.
525 accept_redirects for the interface will be enabled if:
526 - both conf/{all,interface}/accept_redirects are TRUE in the case forwarding
527 for the interface is enabled
529 - at least one of conf/{all,interface}/accept_redirects is TRUE in the case
530 forwarding for the interface is disabled
531 accept_redirects for the interface will be disabled otherwise
536 Enable IP forwarding on this interface.
538 mc_forwarding - BOOLEAN
539 Do multicast routing. The kernel needs to be compiled with CONFIG_MROUTE
540 and a multicast routing daemon is required.
541 conf/all/mc_forwarding must also be set to TRUE to enable multicast routing
545 Integer value used to differentiate the devices by the medium they
546 are attached to. Two devices can have different id values when
547 the broadcast packets are received only on one of them.
548 The default value 0 means that the device is the only interface
549 to its medium, value of -1 means that medium is not known.
551 Currently, it is used to change the proxy_arp behavior:
552 the proxy_arp feature is enabled for packets forwarded between
553 two devices attached to different media.
557 proxy_arp for the interface will be enabled if at least one of
558 conf/{all,interface}/proxy_arp is set to TRUE,
559 it will be disabled otherwise
561 shared_media - BOOLEAN
562 Send(router) or accept(host) RFC1620 shared media redirects.
563 Overrides ip_secure_redirects.
564 shared_media for the interface will be enabled if at least one of
565 conf/{all,interface}/shared_media is set to TRUE,
566 it will be disabled otherwise
569 secure_redirects - BOOLEAN
570 Accept ICMP redirect messages only for gateways,
571 listed in default gateway list.
572 secure_redirects for the interface will be enabled if at least one of
573 conf/{all,interface}/secure_redirects is set to TRUE,
574 it will be disabled otherwise
577 send_redirects - BOOLEAN
578 Send redirects, if router.
579 send_redirects for the interface will be enabled if at least one of
580 conf/{all,interface}/send_redirects is set to TRUE,
581 it will be disabled otherwise
584 bootp_relay - BOOLEAN
585 Accept packets with source address 0.b.c.d destined
586 not to this host as local ones. It is supposed, that
587 BOOTP relay daemon will catch and forward such packets.
588 conf/all/bootp_relay must also be set to TRUE to enable BOOTP relay
593 accept_source_route - BOOLEAN
594 Accept packets with SRR option.
595 conf/all/accept_source_route must also be set to TRUE to accept packets
596 with SRR option on the interface
597 default TRUE (router)
601 1 - do source validation by reversed path, as specified in RFC1812
602 Recommended option for single homed hosts and stub network
603 routers. Could cause troubles for complicated (not loop free)
604 networks running a slow unreliable protocol (sort of RIP),
605 or using static routes.
607 0 - No source validation.
609 conf/all/rp_filter must also be set to TRUE to do source validation
612 Default value is 0. Note that some distributions enable it
616 1 - Allows you to have multiple network interfaces on the same
617 subnet, and have the ARPs for each interface be answered
618 based on whether or not the kernel would route a packet from
619 the ARP'd IP out that interface (therefore you must use source
620 based routing for this to work). In other words it allows control
621 of which cards (usually 1) will respond to an arp request.
623 0 - (default) The kernel can respond to arp requests with addresses
624 from other interfaces. This may seem wrong but it usually makes
625 sense, because it increases the chance of successful communication.
626 IP addresses are owned by the complete host on Linux, not by
627 particular interfaces. Only for more complex setups like load-
628 balancing, does this behaviour cause problems.
630 arp_filter for the interface will be enabled if at least one of
631 conf/{all,interface}/arp_filter is set to TRUE,
632 it will be disabled otherwise
634 arp_announce - INTEGER
635 Define different restriction levels for announcing the local
636 source IP address from IP packets in ARP requests sent on
638 0 - (default) Use any local address, configured on any interface
639 1 - Try to avoid local addresses that are not in the target's
640 subnet for this interface. This mode is useful when target
641 hosts reachable via this interface require the source IP
642 address in ARP requests to be part of their logical network
643 configured on the receiving interface. When we generate the
644 request we will check all our subnets that include the
645 target IP and will preserve the source address if it is from
646 such subnet. If there is no such subnet we select source
647 address according to the rules for level 2.
648 2 - Always use the best local address for this target.
649 In this mode we ignore the source address in the IP packet
650 and try to select local address that we prefer for talks with
651 the target host. Such local address is selected by looking
652 for primary IP addresses on all our subnets on the outgoing
653 interface that include the target IP address. If no suitable
654 local address is found we select the first local address
655 we have on the outgoing interface or on all other interfaces,
656 with the hope we will receive reply for our request and
657 even sometimes no matter the source IP address we announce.
659 The max value from conf/{all,interface}/arp_announce is used.
661 Increasing the restriction level gives more chance for
662 receiving answer from the resolved target while decreasing
663 the level announces more valid sender's information.
666 Define different modes for sending replies in response to
667 received ARP requests that resolve local target IP addresses:
668 0 - (default): reply for any local target IP address, configured
670 1 - reply only if the target IP address is local address
671 configured on the incoming interface
672 2 - reply only if the target IP address is local address
673 configured on the incoming interface and both with the
674 sender's IP address are part from same subnet on this interface
675 3 - do not reply for local addresses configured with scope host,
676 only resolutions for global and link addresses are replied
678 8 - do not reply for all local addresses
680 The max value from conf/{all,interface}/arp_ignore is used
681 when ARP request is received on the {interface}
684 Define behavior when gratuitous arp replies are received:
685 0 - drop gratuitous arp frames
686 1 - accept gratuitous arp frames
688 app_solicit - INTEGER
689 The maximum number of probes to send to the user space ARP daemon
690 via netlink before dropping back to multicast probes (see
691 mcast_solicit). Defaults to 0.
693 disable_policy - BOOLEAN
694 Disable IPSEC policy (SPD) for this interface
696 disable_xfrm - BOOLEAN
697 Disable IPSEC encryption on this interface, whatever the policy
702 Allows you to write a number, which can be used as required.
705 (1) Jiffie: internal timeunit for the kernel. On the i386 1/100s, on the
706 Alpha 1/1024s. See the HZ define in /usr/include/asm/param.h for the exact
707 value on your system.
716 delon.nicolas@wanadoo.fr
721 /proc/sys/net/ipv6/* Variables:
723 IPv6 has no global variables such as tcp_*. tcp_* settings under ipv4/ also
724 apply to IPv6 [XXX?].
727 Default value for IPV6_V6ONLY socket option,
728 which restricts use of the IPv6 socket to IPv6 communication
730 TRUE: disable IPv4-mapped address feature
731 FALSE: enable IPv4-mapped address feature
733 Default: FALSE (as specified in RFC2553bis)
737 ip6frag_high_thresh - INTEGER
738 Maximum memory used to reassemble IPv6 fragments. When
739 ip6frag_high_thresh bytes of memory is allocated for this purpose,
740 the fragment handler will toss packets until ip6frag_low_thresh
743 ip6frag_low_thresh - INTEGER
744 See ip6frag_high_thresh
746 ip6frag_time - INTEGER
747 Time in seconds to keep an IPv6 fragment in memory.
749 ip6frag_secret_interval - INTEGER
750 Regeneration interval (in seconds) of the hash secret (or lifetime
751 for the hash secret) for IPv6 fragments.
755 Change the interface-specific default settings.
759 Change all the interface-specific settings.
761 [XXX: Other special features than forwarding?]
763 conf/all/forwarding - BOOLEAN
764 Enable global IPv6 forwarding between all interfaces.
766 IPv4 and IPv6 work differently here; e.g. netfilter must be used
767 to control which interfaces may forward packets and which not.
769 This also sets all interfaces' Host/Router setting
770 'forwarding' to the specified value. See below for details.
772 This referred to as global forwarding.
778 Change special settings per interface.
780 The functional behaviour for certain settings is different
781 depending on whether local forwarding is enabled or not.
784 Accept Router Advertisements; autoconfigure using them.
786 Functional default: enabled if local forwarding is disabled.
787 disabled if local forwarding is enabled.
789 accept_ra_defrtr - BOOLEAN
790 Learn default router in Router Advertisement.
792 Functional default: enabled if accept_ra is enabled.
793 disabled if accept_ra is disabled.
795 accept_ra_pinfo - BOOLEAN
796 Learn Prefix Information in Router Advertisement.
798 Functional default: enabled if accept_ra is enabled.
799 disabled if accept_ra is disabled.
801 accept_ra_rt_info_max_plen - INTEGER
802 Maximum prefix length of Route Information in RA.
804 Route Information w/ prefix larger than or equal to this
805 variable shall be ignored.
807 Functional default: 0 if accept_ra_rtr_pref is enabled.
808 -1 if accept_ra_rtr_pref is disabled.
810 accept_ra_rtr_pref - BOOLEAN
811 Accept Router Preference in RA.
813 Functional default: enabled if accept_ra is enabled.
814 disabled if accept_ra is disabled.
816 accept_redirects - BOOLEAN
819 Functional default: enabled if local forwarding is disabled.
820 disabled if local forwarding is enabled.
823 Autoconfigure addresses using Prefix Information in Router
826 Functional default: enabled if accept_ra_pinfo is enabled.
827 disabled if accept_ra_pinfo is disabled.
829 dad_transmits - INTEGER
830 The amount of Duplicate Address Detection probes to send.
834 Configure interface-specific Host/Router behaviour.
836 Note: It is recommended to have the same setting on all
837 interfaces; mixed router/host scenarios are rather uncommon.
841 By default, Host behaviour is assumed. This means:
843 1. IsRouter flag is not set in Neighbour Advertisements.
844 2. Router Solicitations are being sent when necessary.
845 3. If accept_ra is TRUE (default), accept Router
846 Advertisements (and do autoconfiguration).
847 4. If accept_redirects is TRUE (default), accept Redirects.
851 If local forwarding is enabled, Router behaviour is assumed.
852 This means exactly the reverse from the above:
854 1. IsRouter flag is set in Neighbour Advertisements.
855 2. Router Solicitations are not sent.
856 3. Router Advertisements are ignored.
857 4. Redirects are ignored.
859 Default: FALSE if global forwarding is disabled (default),
863 Default Hop Limit to set.
867 Default Maximum Transfer Unit
868 Default: 1280 (IPv6 required minimum)
870 router_probe_interval - INTEGER
871 Minimum interval (in seconds) between Router Probing described
876 router_solicitation_delay - INTEGER
877 Number of seconds to wait after interface is brought up
878 before sending Router Solicitations.
881 router_solicitation_interval - INTEGER
882 Number of seconds to wait between Router Solicitations.
885 router_solicitations - INTEGER
886 Number of Router Solicitations to send until assuming no
890 use_tempaddr - INTEGER
891 Preference for Privacy Extensions (RFC3041).
892 <= 0 : disable Privacy Extensions
893 == 1 : enable Privacy Extensions, but prefer public
894 addresses over temporary addresses.
895 > 1 : enable Privacy Extensions and prefer temporary
896 addresses over public addresses.
897 Default: 0 (for most devices)
898 -1 (for point-to-point devices and loopback devices)
900 temp_valid_lft - INTEGER
901 valid lifetime (in seconds) for temporary addresses.
902 Default: 604800 (7 days)
904 temp_prefered_lft - INTEGER
905 Preferred lifetime (in seconds) for temporary addresses.
906 Default: 86400 (1 day)
908 max_desync_factor - INTEGER
909 Maximum value for DESYNC_FACTOR, which is a random value
910 that ensures that clients don't synchronize with each
911 other and generate new addresses at exactly the same time.
915 regen_max_retry - INTEGER
916 Number of attempts before give up attempting to generate
917 valid temporary addresses.
920 max_addresses - INTEGER
921 Number of maximum addresses per interface. 0 disables limitation.
922 It is recommended not set too large value (or 0) because it would
923 be too easy way to crash kernel to allow to create too much of
924 autoconfigured addresses.
929 Limit the maximal rates for sending ICMPv6 packets.
930 0 to disable any limiting, otherwise the maximal rate in jiffies(1)
935 Pekka Savola <pekkas@netcore.fi>
936 YOSHIFUJI Hideaki / USAGI Project <yoshfuji@linux-ipv6.org>
939 /proc/sys/net/bridge/* Variables:
941 bridge-nf-call-arptables - BOOLEAN
942 1 : pass bridged ARP traffic to arptables' FORWARD chain.
946 bridge-nf-call-iptables - BOOLEAN
947 1 : pass bridged IPv4 traffic to iptables' chains.
951 bridge-nf-call-ip6tables - BOOLEAN
952 1 : pass bridged IPv6 traffic to ip6tables' chains.
956 bridge-nf-filter-vlan-tagged - BOOLEAN
957 1 : pass bridged vlan-tagged ARP/IP traffic to arptables/iptables.
965 discovery_slots FIXME
966 discovery_timeout FIXME
967 fast_poll_increase FIXME
968 ip6_queue_maxlen FIXME
969 lap_keepalive_time FIXME
973 max_noreply_time FIXME
974 max_tx_data_size FIXME
976 min_tx_turn_time FIXME
981 warn_noreply_time FIXME
983 $Id: ip-sysctl.txt,v 1.20 2001/12/13 09:00:18 davem Exp $