ip-sysctl

Page based on Documentation/networking/ip-sysctl.txt.

Contents


/proc/sys/net/ipv4

ip_forward 
BOOLEAN 0 - disabled (default)
Forward Packets between interfaces. This variable is special, its change resets all configuration parameters to their default state (RFC1122 for hosts, RFC1812 for routers)
ip_default_ttl 
INTEGER default 64
ip_no_pmtu_disc 
BOOLEAN default FALSE
Disable Path MTU Discovery.
min_pmtu 
INTEGER default 562
Minimum discovered Path MTU
mtu_expires 
INTEGER
Time, in seconds, that cached PMTU information is kept.
min_adv_mss 
INTEGER
The advertised MSS depends on the first hop route MTU, but will never be lower than this setting.


IP Fragmentation

ipfrag_high_thresh 
INTEGER
Maximum memory used to reassemble IP fragments. When ipfrag_high_thresh bytes of memory is allocated for this purpose, the fragment handler will toss packets until ipfrag_low_thresh is reached.
ipfrag_low_thresh 
INTEGER
See ipfrag_high_thresh
ipfrag_time 
INTEGER
Time in seconds to keep an IP fragment in memory.
ipfrag_secret_interval 
INTEGER default: 600

Regeneration interval (in seconds) of the hash secret (or lifetime for the hash secret) for IP fragments.

ipfrag_max_dist 
INTEGER default: 64
ipfrag_max_dist is a non-negative integer value which defines the maximum "disorder" which is allowed among fragments which share a common IP source address. Note that reordering of packets is not unusual, but if a large number of fragments arrive from a source IP address while a particular fragment queue remains incomplete, it probably indicates that one or more fragments belonging to that queue have been lost. When ipfrag_max_dist is positive, an additional check is done on fragments before they are added to a reassembly queue - if ipfrag_max_dist (or more) fragments have arrived from a particular IP address between additions to any IP fragment queue using that source address, it's presumed that one or more fragments in the queue are lost. The existing fragment queue will be dropped, and a new one started. An ipfrag_max_dist value of zero disables this check.
Using a very small value, e.g. 1 or 2, for ipfrag_max_dist can result in unnecessarily dropping fragment queues when normal reordering of packets occurs, which could lead to poor application performance. Using a very large value, e.g. 50000, increases the likelihood of incorrectly reassembling IP fragments that originate from different IP datagrams, which could result in data corruption.


INET peer storage

inet_peer_threshold 
INTEGER
The approximate size of the storage. Starting from this threshold entries will be thrown aggressively. This threshold also determines entries' time-to-live and time intervals between garbage collection passes. More entries, less time-to-live, less GC interval.
inet_peer_minttl 
INTEGER
Minimum time-to-live of entries. Should be enough to cover fragment time-to-live on the reassembling side. This minimum time-to-live is guaranteed if the pool size is less than inet_peer_threshold. Measured in jiffies(1).
inet_peer_maxttl 
INTEGER
Maximum time-to-live of entries. Unused entries will expire after this period of time if there is no memory pressure on the pool (i.e. when the number of entries in the pool is very small). Measured in jiffies(1).
inet_peer_gc_mintime 
INTEGER
Minimum interval between garbage collection passes. This interval is in effect under high memory pressure on the pool. Measured in jiffies(1).
inet_peer_gc_maxtime 
INTEGER
Minimum interval between garbage collection passes. This interval is in effect under low (or absent) memory pressure on the pool. Measured in jiffies(1).


=TCP variables

somaxconn 
INTEGER default 128
Limit of socket listen() backlog, known in userspace as SOMAXCONN.

See also tcp_max_syn_backlog for additional tuning for TCP sockets.

tcp_abc 
INTEGER default 0 (off)
Controls Appropriate Byte Count (ABC) defined in RFC3465. ABC is a way of increasing congestion window (cwnd) more slowly in response to partial acknowledgments.

Possible values are:

increase cwnd once per acknowledgment (no ABC)
increase cwnd once per acknowledgment of full sized segment
allow increase cwnd by two if acknowledgment is of two segments to compensate for delayed acknowledgments.

tcp_abort_on_overflow 
BOOLEAN
If listening service is too slow to accept new connections, reset them. Default state is FALSE. It means that if overflow occurred due to a burst, connection will recover. Enable this option _only_ if you are really sure that listening daemon cannot be tuned to accept connections faster. Enabling this option can harm clients of your server.
tcp_adv_win_scale 
INTEGER (default 2)
Count buffering overhead as
if tcp_adv_win_scale > 0
	bytes/2^tcp_adv_win_scale
else
 bytes-bytes/2^(-tcp_adv_win_scale)

tcp_allowed_congestion_control 
STRING
Show/set the congestion control choices available to non-privileged processes. The list is a subset of those listed in tcp_available_congestion_control.
tcp_app_win 
INTEGER (default 31)
Reserve max(window/2^tcp_app_win, mss) of window for application buffer. Value 0 is special, it means that nothing is reserved.
tcp_available_congestion_control 
STRING
Shows the available congestion control choices that are registered. More congestion control algorithms may be available as modules, but not loaded.
tcp_congestion_control 
STRING
Set the congestion control algorithm to be used for new connections. The algorithm "reno" is always available, but additional choices may be available based on kernel configuration.
tcp_dsack 
BOOLEAN
Allows TCP to send "duplicate" SACKs.
tcp_ecn 
BOOLEAN
Enable Explicit Congestion Notification in TCP.
tcp_fack 
BOOLEAN
Enable FACK congestion avoidance and fast retransmission. The value is not used, if tcp_sack is not enabled.
tcp_fin_timeout 
INTEGER
Time to hold socket in state FIN-WAIT-2, if it was closed by our side. Peer can be broken and never close its side, or even died unexpectedly. Default value is 60sec. Usual value used in 2.2 was 180 seconds, you may restore it, but remember that if your machine is even underloaded WEB server, you risk to overflow memory with kilotons of dead sockets, FIN-WAIT-2 sockets are less dangerous than FIN-WAIT-1, because they eat maximum 1.5K of memory, but they tend to live longer. Cf. tcp_max_orphans.
tcp_frto 
BOOLEAN
Enables F-RTO, an enhanced recovery algorithm for TCP retransmission timeouts. It is particularly beneficial in wireless environments where packet loss is typically due to random radio interference rather than intermediate router congestion.
tcp_keepalive_time 
INTEGER (default 2hrs)

How often TCP sends out keepalive messages when keepalive is enabled.

tcp_keepalive_probes 
INTEGER
How many keepalive probes TCP sends out, until it decides that the connection is broken. Default value: 9.
tcp_keepalive_intvl 
INTEGER (default 75sec)
How frequently the probes are send out. Multiplied by tcp_keepalive_probes it is time to kill not responding connection,

after probes started.

tcp_low_latency 
BOOLEAN (default 0)
If set, the TCP stack makes decisions that prefer lower latency as opposed to higher throughput. By default, this option is not set meaning that higher throughput is preferred. An example of an application where this default should be changed would be a Beowulf compute cluster.

tcp_max_orphans 
INTEGER
Maximal number of TCP sockets not attached to any user file handle, held by system. If this number is exceeded orphaned connections are reset immediately and warning is printed. This limit exists only to prevent simple DoS attacks, you _must_ not rely on this or lower the limit artificially, but rather increase it (probably, after increasing installed memory), if network conditions require more than default value, and tune network services to linger and kill such states more aggressively. Let me to remind again: each orphan eats up to ~64K of unswappable memory.
tcp_max_syn_backlog 
INTEGER (default 1024)
Maximal number of remembered connection requests, which are still did not receive an acknowledgment from connecting client. Default value is 1024 for systems with more than 128Mb of memory, and 128 for low memory machines. If server suffers of overload, try to increase this number.
tcp_max_tw_buckets 
INTEGER
Maximal number of timewait sockets held by system simultaneously. If this number is exceeded time-wait socket is immediately destroyed and warning is printed. This limit exists only to prevent simple DoS attacks, you _must_ not lower the limit artificially,

but rather increase it (probably, after increasing installed memory), if network conditions require more than default value.

tcp_mem 
vector of 3 INTEGERs: min, pressure, max
min 
below this number of pages TCP is not bothered about its memory appetite.
pressure 
when amount of memory allocated by TCP exceeds this number of pages, TCP moderates its memory consumption and enters memory pressure mode, which is exited when memory consumption falls under "min".
max 
number of pages allowed for queueing by all TCP sockets.

Defaults are calculated at boot time from amount of available memory.

tcp_orphan_retries 
INTEGER
How may times to retry before killing TCP connection, closed by our side. Default value 7 corresponds to ~50sec-16min depending on RTO. If you machine is loaded WEB server, you should think about lowering this value, such sockets may consume significant resources. Cf. tcp_max_orphans.
tcp_reordering 
INTEGER (default 3)
Maximal reordering of packets in a TCP stream.
tcp_retrans_collapse 
BOOLEAN
Bug-to-bug compatibility with some broken printers. On retransmit try to send bigger packets to work around bugs in certain TCP stacks.
tcp_retries1 
INTEGER
How many times to retry before deciding that something is wrong and it is necessary to report this suspicion to network layer. Minimal RFC value is 3, it is default, which corresponds to ~3sec-8min depending on RTO.
tcp_retries2 
INTEGER
How may times to retry before killing alive TCP connection. RFC1122 says that the limit should be longer than 100 sec. It is too small number. Default value 15 corresponds to ~13-30min depending on RTO.
tcp_rfc1337 
BOOLEAN (default 0)
If set, the TCP stack behaves conforming to RFC1337. If unset, we are not conforming to RFC, but prevent TCP TIME_WAIT assassination.
tcp_rmem 
vector of 3 INTEGERs: min, default, max
min 
Minimal size of receive buffer used by TCP sockets. It is guaranteed to each TCP socket, even under moderate memory pressure.
default 
default size of receive buffer used by TCP sockets. This value overrides net.core.rmem_default used by other protocols. Default: 87380 bytes. This value results in window of 65535 with default setting of tcp_adv_win_scale and tcp_app_win:0 and a bit less for default tcp_app_win. See below about these variables.
max 
maximal size of receive buffer allowed for automatically selected receiver buffers for TCP socket. This value does not override net.core.rmem_max, "static" selection via SO_RCVBUF does not use this.
tcp_sack 
BOOLEAN
Enable select acknowledgments (SACKS).
tcp_slow_start_after_idle 
BOOLEAN (default 1)
If set, provide RFC2861 behavior and time out the congestion window after an idle period. An idle period is defined at the current RTO. If unset, the congestion window will not be timed out after an idle period.
tcp_stdurg 
BOOLEAN (default FALSE)
Use the Host requirements interpretation of the TCP urg pointer field. Most hosts use the older BSD interpretation, so if you turn this on Linux might not communicate correctly with them.
tcp_synack_retries 
INTEGER
Number of times SYNACKs for a passive TCP connection attempt will be retransmitted. Should not be higher than 255. Default value is 5, which corresponds to ~180seconds.
tcp_syncookies 
BOOLEAN (defalt FALSE)
Only valid when the kernel was compiled with CONFIG_SYNCOOKIES. Send out syncookies when the syn backlog queue of a socket overflows. This is to prevent against the common 'syn flood attack'

Note, that syncookies is fallback facility. It MUST NOT be used to help highly loaded servers to stand against legal connection rate. If you see synflood warnings in your logs, but investigation shows that they occur because of overload with legal connections, you should tune another parameters until this warning disappear.
See: tcp_max_syn_backlog, tcp_synack_retries, tcp_abort_on_overflow.

syncookies seriously violate TCP protocol, do not allow to use TCP extensions, can result in serious degradation of some services (f.e. SMTP relaying), visible not by you, but your clients and relays, contacting you. While you see synflood warnings in logs not being really flooded, your server is seriously misconfigured.

tcp_syn_retries 
INTEGER
Number of times initial SYNs for an active TCP connection attempt will be retransmitted. Should not be higher than 255. Default value is 5, which corresponds to ~180seconds.
tcp_timestamps 
BOOLEAN
Enable timestamps as defined in RFC1323.
tcp_tso_win_divisor 
INTEGER (default 3)
This allows control over what percentage of the congestion window can be consumed by a single TSO frame. The setting of this parameter is a choice between burstiness and building larger TSO frames.
tcp_tw_recycle 
BOOLEAN (default 0)
Enable fast recycling TIME-WAIT sockets. It should not be changed without advice/request of technical experts.
tcp_tw_reuse 
BOOLEAN (default 0)
Allow to reuse TIME-WAIT sockets for new connections when it is safe from protocol viewpoint. It should not be changed without advice/request of technical experts.
tcp_window_scaling 
BOOLEAN
Enable window scaling as defined in RFC1323.
tcp_wmem 
vector of 3 INTEGERs: min, default, max
min 
Amount of memory reserved for send buffers for TCP socket. Each TCP socket has rights to use it due to fact of its birth.
default 
Amount of memory allowed for send buffers for TCP socket by default. This value overrides net.core.wmem_default used by other protocols, it is usually lower than net.core.wmem_default.
max 
Maximal amount of memory allowed for automatically selected send buffers for TCP socket. This value does not override net.core.wmem_max, "static" selection via SO_SNDBUF does not use this.
tcp_workaround_signed_windows 
BOOLEAN (default 0)
If set, assume no receipt of a window scaling option means the remote TCP is broken and treats the window as a signed quantity. If unset, assume the remote TCP is not broken even if we do not receive a window scaling option from them.


CIPSOv4

cipso_cache_enable 
BOOLEAN (default 1)
If set, enable additions to and lookups from the CIPSO label mapping cache. If unset, additions are ignored and lookups always result in a miss. However, regardless of the setting the cache is still invalidated when required when means you can safely toggle this on and off and the cache will always be "safe".
cipso_cache_bucket_size 
INTEGER (default 10)
The CIPSO label cache consists of a fixed size hash table with each hash bucket containing a number of cache entries. This variable limits the number of entries in each hash bucket; the larger the value the more CIPSO label mappings that can be cached. When the number of entries in a given hash bucket reaches this limit adding new entries causes the oldest entry in the bucket to be removed to make room.
cipso_rbm_optfmt 
BOOLEAN (default 0)
Enable the "Optimized Tag 1 Format" as defined in section 3.4.2.6 of the CIPSO draft specification (see Documentation/netlabel for details). This means that when set the CIPSO tag will be padded with empty categories in order to make the packet data 32-bit aligned.
cipso_rbm_structvalid 
BOOLEAN (default 0)
If set, do a very strict check of the CIPSO option when ip_options_compile() is called. If unset, relax the checks done during ip_options_compile(). Either way is "safe" as errors are caught else where in the CIPSO processing code but setting this to 0 (False) should result in less work (i.e. it should be faster) but could cause problems with other implementations that require strict checking.


IP Variables

ip_local_port_range 
2 INTEGERS
Defines the local port range that is used by TCP and UDP to choose the local port. The first number is the first, the second the last local port number. Default value depends on amount of memory available on the system:
32768-61000
1024-4999 or less.
This number defines number of active connections, which this system can issue simultaneously to systems not supporting TCP extensions (timestamps). With tcp_tw_recycle enabled (i.e. by default) range 1024-4999 is enough to issue up to 2000 connections per second to systems supporting timestamps.
ip_nonlocal_bind 
BOOLEAN (default 0)
If set, allows processes to bind() to non-local IP addresses, which can be quite useful - but may break some applications.
ip_dynaddr 
BOOLEAN (default 0)
If set non-zero, enables support for dynamic addresses. If set to a non-zero value larger than 1, a kernel log message will be printed when dynamic address rewriting occurs.
icmp_echo_ignore_all 
BOOLEAN (default 0)
If set non-zero, then the kernel will ignore all ICMP ECHO requests sent to it.
icmp_echo_ignore_broadcasts 
BOOLEAN (default 1)
If set non-zero, then the kernel will ignore all ICMP ECHO and TIMESTAMP requests sent to it via broadcast/multicast.
icmp_ratelimit 
INTEGER (default 100)
Limit the maximal rates for sending ICMP packets whose type matches icmp_ratemask (see below) to specific targets. 0 to disable any limiting, otherwise the maximal rate in jiffies(1)

icmp_ratemask 
INTEGER
Mask made of ICMP types for which rates are being limited.
 Significant bits: IHGFEDCBA9876543210
 Default mask:     0000001100000011000 (6168)
 Bit definitions (see include/linux/icmp.h):

0 Echo Reply
3 Destination Unreachable *
4 Source Quench *
5 Redirect
8 Echo Request
B Time Exceeded *
C Parameter Problem *
D Timestamp Request
E Timestamp Reply
F Info Request
G Info Reply
H Address Mask Request
I Address Mask Reply

 * These are rate limited by default (see default mask above)
icmp_ignore_bogus_error_responses 
BOOLEAN (default FALSE)
Some routers violate RFC1122 by sending bogus responses to broadcast frames. Such violations are normally logged via a kernel warning. If this is set to TRUE, the kernel will not give such warnings, which will avoid log file clutter.
icmp_errors_use_inbound_ifaddr 
BOOLEAN (default 0)a
If zero, icmp error messages are sent with the primary address of the exiting interface. If non-zero, the message will be sent with the primary address of the interface that received the packet that caused the icmp error. This is the behaviour network many administrators will expect from a router. And it can make debugging complicated network layouts much easier.

Note that if no primary address exists for the interface selected, then the primary address of the first non-loopback interface that has one will be used regardless of this setting.

igmp_max_memberships 
INTEGER (default 20)
Change the maximum number of multicast groups we can subscribe to.


conf/interface

changes special settings per interface (where "interface" is  the name of your network interface) conf/all/  is special, changes the settings for all interfaces.
log_martians 
BOOLEAN
Log packets with impossible addresses to kernel log. log_martians for the interface will be enabled if at least one of conf/{all,interface}/log_martians is set to TRUE, it will be disabled otherwise
accept_redirects 
BOOLEAN
Accept ICMP redirect messages.
 accept_redirects for the interface will be enabled if:
 - both conf/{all,interface}/accept_redirects are TRUE in the case forwarding for the interface is enabled
 or
 - at least one of conf/{all,interface}/accept_redirects is TRUE in the case forwarding for the interface is disabled
 accept_redirects for the interface will be disabled otherwise
 default TRUE (host)

FALSE (router)

forwarding 
BOOLEAN
Enable IP forwarding on this interface.
mc_forwarding 
BOOLEAN
Do multicast routing. The kernel needs to be compiled with CONFIG_MROUTE and a multicast routing daemon is required. conf/all/mc_forwarding must also be set to TRUE to enable multicast routing for the interface
medium_id 
INTEGER
Integer value used to differentiate the devices by the medium they are attached to. Two devices can have different id values when the broadcast packets are received only on one of them. The default value 0 means that the device is the only interface to its medium, value of -1 means that medium is not known.

Currently, it is used to change the proxy_arp behavior: the proxy_arp feature is enabled for packets forwarded between two devices attached to different media.

proxy_arp 
BOOLEAN
Do proxy arp. proxy_arp for the interface will be enabled if at least one of conf/{all,interface}/proxy_arp is set to TRUE, it will be disabled otherwise
shared_media 
BOOLEAN (default TRUE)
Send(router) or accept(host) RFC1620 shared media redirects. Overrides ip_secure_redirects. shared_media for the interface will be enabled if at least one of conf/{all,interface}/shared_media is set to TRUE, it will be disabled otherwise
secure_redirects 
BOOLEAN (default TRUE)
Accept ICMP redirect messages only for gateways, listed in default gateway list. secure_redirects for the interface will be enabled if at least one of conf/{all,interface}/secure_redirects is set to TRUE, it will be disabled otherwise
send_redirects 
BOOLEAN (default TRUE)
Send redirects, if router. send_redirects for the interface will be enabled if at least one of conf/{all,interface}/send_redirects is set to TRUE, it will be disabled otherwise.

bootp_relay 
BOOLEAN (default FALSE)
Accept packets with source address 0.b.c.d destined not to this host as local ones. It is supposed, that BOOTP relay daemon will catch and forward such packets. conf/all/bootp_relay must also be set to TRUE to enable BOOTP relay for the interface

Not Implemented Yet.

accept_source_route 
BOOLEAN
Accept packets with SRR option. conf/all/accept_source_route must also be set to TRUE to accept packets with SRR option on the interface

default TRUE (router) / FALSE (host)

rp_filter 
BOOLEAN
do source validation by reversed path, as specified in RFC1812. Recommended option for single homed hosts and stub network routers. Could cause troubles for complicated (not loop free) networks running a slow unreliable protocol (sort of RIP), or using static routes.
No source validation.

conf/all/rp_filter must also be set to TRUE to do source validation on the interface. Default value is 0. Note that some distributions enable it in startup scripts.

arp_filter 
BOOLEAN
1
Allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP'd IP out that interface (therefore you must use source based routing for this to work). In other words it allows control of which cards (usually 1) will respond to an arp request.
(default) The kernel can respond to arp requests with addresses from other interfaces. This may seem wrong but it usually makes sense, because it increases the chance of successful communication. IP addresses are owned by the complete host on Linux, not by particular interfaces. Only for more complex setups like load-balancing, does this behaviour cause problems.

arp_filter for the interface will be enabled if at least one of conf/{all,interface}/arp_filter is set to TRUE,it will be disabled otherwise

arp_announce 
INTEGER
Define different restriction levels for announcing the local source IP address from IP packets in ARP requests sent on interface:
(default) Use any local address, configured on any interface
Try to avoid local addresses that are not in the target's subnet for this interface. This mode is useful when target hosts reachable via this interface require the source IP address in ARP requests to be part of their logical network configured on the receiving interface. When we generate the request we will check all our subnets that include the target IP and will preserve the source address if it is from such subnet. If there is no such subnet we select source address according to the rules for level 2.
Always use the best local address for this target. In this mode we ignore the source address in the IP packet and try to select local address that we prefer for talks with the target host. Such local address is selected by looking for primary IP addresses on all our subnets on the outgoing interface that include the target IP address. If no suitable local address is found we select the first local address we have on the outgoing interface or on all other interfaces, with the hope we will receive reply for our request and even sometimes no matter the source IP address we announce.

The max value from conf/{all,interface}/arp_announce is used.
Increasing the restriction level gives more chance for receiving answer from the resolved target while decreasing the level announces more valid sender's information.

arp_ignore 
INTEGER
Define different modes for sending replies in response to received ARP requests that resolve local target IP addresses:
(default): reply for any local target IP address, configured on any interface
reply only if the target IP address is local address configured on the incoming interface
reply only if the target IP address is local address configured on the incoming interface and both with the sender's IP address are part from same subnet on this interface
do not reply for local addresses configured with scope host, only resolutions for global and link addresses are replied
4-7 
reserved
do not reply for all local addresses
The max value from conf/{all,interface}/arp_ignore is used when ARP request is received on the {interface}
arp_accept 
BOOLEAN
Define behavior when gratuitous arp replies are received:
drop gratuitous arp frames
accept gratuitous arp frames
app_solicit 
INTEGER
The maximum number of probes to send to the user space ARP daemon via netlink before dropping back to multicast probes (see mcast_solicit). Defaults to 0.
disable_policy 
BOOLEAN
Disable IPSEC policy (SPD) for this interface
disable_xfrm 
BOOLEAN
Disable IPSEC encryption on this interface, whatever the policy
tag 
INTEGER
Allows you to write a number, which can be used as required. Default value is 0.


/proc/sys/net/ipv6/*

IPv6 has no global variables such as tcp_*. tcp_* settings under ipv4/ also
apply to IPv6 [XXX?].

bindv6only 
BOOLEAN
Default value for IPV6_V6ONLY socket option,which restricts use of the IPv6 socket to IPv6 communication only.
TRUE 
disable IPv4-mapped address feature
FALSE 
enable IPv4-mapped address feature
Default: FALSE (as specified in RFC2553bis)


IPv6 Fragmentation

ip6frag_high_thresh 
INTEGER
Maximum memory used to reassemble IPv6 fragments. When ip6frag_high_thresh bytes of memory is allocated for this purpose, the fragment handler will toss packets until ip6frag_low_thresh is reached.
ip6frag_low_thresh 
INTEGER
See ip6frag_high_thresh
ip6frag_time 
INTEGER
Time in seconds to keep an IPv6 fragment in memory.
ip6frag_secret_interval 
INTEGER
Regeneration interval (in seconds) of the hash secret (or lifetime for the hash secret) for IPv6 fragments. Default: 600


conf/default

Change the interface-specific default settings.


conf/all

Change all the interface-specific settings.

conf/all/forwarding 
BOOLEAN
Enable global IPv6 forwarding between all interfaces. IPv4 and IPv6 work differently here; e.g. netfilter must be used to control which interfaces may forward packets and which not.

This also sets all interfaces' Host/Router setting 'forwarding' to the specified value. See below for details. This referred to as global forwarding.

proxy_ndp 
BOOLEAN
Do proxy ndp.


conf/interface/

Change special settings per interface.

The functional behaviour for certain settings is different depending on whether local forwarding is enabled or not.

accept_ra 
BOOLEAN
Accept Router Advertisements; autoconfigure using them. Functional default: enabled if local forwarding is disabled and disabled if local forwarding is enabled.
accept_ra_defrtr 
BOOLEAN
Learn default router in Router Advertisement. Functional default: enabled if accept_ra is enabled, disabled if accept_ra is disabled.
accept_ra_pinfo 
BOOLEAN
Learn Prefix Information in Router Advertisement. Functional default: enabled if accept_ra is enabled, disabled if accept_ra is disabled.
accept_ra_rt_info_max_plen 
INTEGER
Maximum prefix length of Route Information in RA.
Route Information w/ prefix larger than or equal to this variable shall be ignored.
Functional default: 0 if accept_ra_rtr_pref is enabled. -1 if accept_ra_rtr_pref is disabled.
accept_ra_rtr_pref 
BOOLEAN
Accept Router Preference in RA.
Functional default: enabled if accept_ra is enabled. disabled if accept_ra is disabled.
accept_redirects 
BOOLEAN
Accept Redirects.
Functional default: enabled if local forwarding is disabled. disabled if local forwarding is enabled.
autoconf 
BOOLEAN
Autoconfigure addresses using Prefix Information in Router Advertisements.
Functional default: enabled if accept_ra_pinfo is enabled. disabled if accept_ra_pinfo is disabled.
dad_transmits 
INTEGER
The amount of Duplicate Address Detection probes to send. Default: 1
forwarding 
BOOLEAN
Configure interface-specific Host/Router behaviour.
Note: It is recommended to have the same setting on all interfaces; mixed router/host scenarios are rather uncommon.
FALSE 
By default, Host behaviour is assumed. This means:
  1. IsRouter flag is not set in Neighbour Advertisements.
  2. Router Solicitations are being sent when necessary.
  3. If accept_ra is TRUE (default), accept Router Advertisements (and do autoconfiguration).
  4. If accept_redirects is TRUE (default), accept Redirects.
TRUE 
If local forwarding is enabled, Router behaviour is assumed. This means exactly the reverse from the above:
  1. IsRouter flag is set in Neighbour Advertisements.
  2. Router Solicitations are not sent.
  3. Router Advertisements are ignored.
  4. Redirects are ignored.
Default: FALSE if global forwarding is disabled (default), otherwise TRUE.
hop_limit 
INTEGER
Default Hop Limit to set. Default: 64
mtu 
INTEGER
Default Maximum Transfer Unit. Default: 1280 (IPv6 required minimum)
router_probe_interval 
INTEGER
Minimum interval (in seconds) between Router Probing described in RFC4191. Default: 60
router_solicitation_delay 
INTEGER
Number of seconds to wait after interface is brought up before sending Router Solicitations. Default: 1
router_solicitation_interval 
INTEGER
Number of seconds to wait between Router Solicitations. Default: 4
router_solicitations 
INTEGER
Number of Router Solicitations to send until assuming no routers are present. Default: 3
use_tempaddr 
INTEGER
Preference for Privacy Extensions (RFC3041).
<= 0 
disable Privacy Extensions
== 1 
enable Privacy Extensions, but prefer public addresses over temporary addresses.
> 1 
enable Privacy Extensions and prefer temporary addresses over public addresses.
Default: 0 (for most devices), -1 (for point-to-point devices and loopback devices)
temp_valid_lft 
INTEGER
valid lifetime (in seconds) for temporary addresses. Default: 604800 (7 days)
temp_prefered_lft 
INTEGER
Preferred lifetime (in seconds) for temporary addresses. Default: 86400 (1 day)
max_desync_factor 
INTEGER
Maximum value for DESYNC_FACTOR, which is a random value that ensures that clients don't synchronize with each other and generate new addresses at exactly the same time. value is in seconds. Default: 600
regen_max_retry 
INTEGER
Number of attempts before give up attempting to generate valid temporary addresses. Default: 5
max_addresses 
INTEGER
Number of maximum addresses per interface. 0 disables limitation. It is recommended not set too large value (or 0) because it would be too easy way to crash kernel to allow to create too much of autoconfigured addresses. Default: 16


icmp

ratelimit : INTEGER

Limit the maximal rates for sending ICMPv6 packets.

0 : disable any limiting, otherwise the maximal rate in jiffies(1) (Default: 100)


/proc/sys/net/bridge

bridge-nf-call-arptables 
BOOLEAN

pass bridged ARP traffic to arptables' FORWARD chain. (default)
disable this.
bridge-nf-call-iptables 
BOOLEAN
pass bridged IPv4 traffic to iptables' chains. (default)
disable this.
bridge-nf-call-ip6tables 
BOOLEAN
pass bridged IPv6 traffic to ip6tables' chains. (default)
disable this.
bridge-nf-filter-vlan-tagged 
BOOLEAN
pass bridged vlan-tagged ARP/IP traffic to arptables/iptables. (default)
disable this.
Groups: