1049 lines
36 KiB
Plaintext
1049 lines
36 KiB
Plaintext
/proc/sys/net/ipv4/* Variables:
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ip_forward - BOOLEAN
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0 - disabled (default)
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not 0 - enabled
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Forward Packets between interfaces.
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This variable is special, its change resets all configuration
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parameters to their default state (RFC1122 for hosts, RFC1812
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for routers)
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ip_default_ttl - INTEGER
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default 64
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ip_no_pmtu_disc - BOOLEAN
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Disable Path MTU Discovery.
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default FALSE
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min_pmtu - INTEGER
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default 562 - minimum discovered Path MTU
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mtu_expires - INTEGER
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Time, in seconds, that cached PMTU information is kept.
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min_adv_mss - INTEGER
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The advertised MSS depends on the first hop route MTU, but will
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never be lower than this setting.
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IP Fragmentation:
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ipfrag_high_thresh - INTEGER
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Maximum memory used to reassemble IP fragments. When
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ipfrag_high_thresh bytes of memory is allocated for this purpose,
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the fragment handler will toss packets until ipfrag_low_thresh
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is reached.
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ipfrag_low_thresh - INTEGER
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See ipfrag_high_thresh
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ipfrag_time - INTEGER
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Time in seconds to keep an IP fragment in memory.
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ipfrag_secret_interval - INTEGER
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Regeneration interval (in seconds) of the hash secret (or lifetime
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for the hash secret) for IP fragments.
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Default: 600
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ipfrag_max_dist - INTEGER
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ipfrag_max_dist is a non-negative integer value which defines the
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maximum "disorder" which is allowed among fragments which share a
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common IP source address. Note that reordering of packets is
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not unusual, but if a large number of fragments arrive from a source
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IP address while a particular fragment queue remains incomplete, it
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probably indicates that one or more fragments belonging to that queue
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have been lost. When ipfrag_max_dist is positive, an additional check
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is done on fragments before they are added to a reassembly queue - if
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ipfrag_max_dist (or more) fragments have arrived from a particular IP
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address between additions to any IP fragment queue using that source
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address, it's presumed that one or more fragments in the queue are
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lost. The existing fragment queue will be dropped, and a new one
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started. An ipfrag_max_dist value of zero disables this check.
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Using a very small value, e.g. 1 or 2, for ipfrag_max_dist can
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result in unnecessarily dropping fragment queues when normal
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reordering of packets occurs, which could lead to poor application
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performance. Using a very large value, e.g. 50000, increases the
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likelihood of incorrectly reassembling IP fragments that originate
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from different IP datagrams, which could result in data corruption.
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Default: 64
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INET peer storage:
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inet_peer_threshold - INTEGER
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The approximate size of the storage. Starting from this threshold
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entries will be thrown aggressively. This threshold also determines
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entries' time-to-live and time intervals between garbage collection
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passes. More entries, less time-to-live, less GC interval.
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inet_peer_minttl - INTEGER
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Minimum time-to-live of entries. Should be enough to cover fragment
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time-to-live on the reassembling side. This minimum time-to-live is
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guaranteed if the pool size is less than inet_peer_threshold.
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Measured in jiffies(1).
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inet_peer_maxttl - INTEGER
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Maximum time-to-live of entries. Unused entries will expire after
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this period of time if there is no memory pressure on the pool (i.e.
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when the number of entries in the pool is very small).
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Measured in jiffies(1).
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inet_peer_gc_mintime - INTEGER
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Minimum interval between garbage collection passes. This interval is
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in effect under high memory pressure on the pool.
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Measured in jiffies(1).
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inet_peer_gc_maxtime - INTEGER
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Minimum interval between garbage collection passes. This interval is
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in effect under low (or absent) memory pressure on the pool.
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Measured in jiffies(1).
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TCP variables:
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somaxconn - INTEGER
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Limit of socket listen() backlog, known in userspace as SOMAXCONN.
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Defaults to 128. See also tcp_max_syn_backlog for additional tuning
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for TCP sockets.
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tcp_abc - INTEGER
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Controls Appropriate Byte Count (ABC) defined in RFC3465.
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ABC is a way of increasing congestion window (cwnd) more slowly
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in response to partial acknowledgments.
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Possible values are:
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0 increase cwnd once per acknowledgment (no ABC)
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1 increase cwnd once per acknowledgment of full sized segment
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2 allow increase cwnd by two if acknowledgment is
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of two segments to compensate for delayed acknowledgments.
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Default: 0 (off)
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tcp_abort_on_overflow - BOOLEAN
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If listening service is too slow to accept new connections,
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reset them. Default state is FALSE. It means that if overflow
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occurred due to a burst, connection will recover. Enable this
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option _only_ if you are really sure that listening daemon
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cannot be tuned to accept connections faster. Enabling this
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option can harm clients of your server.
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tcp_adv_win_scale - INTEGER
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Count buffering overhead as bytes/2^tcp_adv_win_scale
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(if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale),
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if it is <= 0.
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Default: 2
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tcp_allowed_congestion_control - STRING
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Show/set the congestion control choices available to non-privileged
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processes. The list is a subset of those listed in
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tcp_available_congestion_control.
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Default is "reno" and the default setting (tcp_congestion_control).
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tcp_app_win - INTEGER
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Reserve max(window/2^tcp_app_win, mss) of window for application
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buffer. Value 0 is special, it means that nothing is reserved.
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Default: 31
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tcp_available_congestion_control - STRING
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Shows the available congestion control choices that are registered.
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More congestion control algorithms may be available as modules,
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but not loaded.
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tcp_base_mss - INTEGER
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The initial value of search_low to be used by Packetization Layer
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Path MTU Discovery (MTU probing). If MTU probing is enabled,
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this is the inital MSS used by the connection.
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tcp_congestion_control - STRING
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Set the congestion control algorithm to be used for new
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connections. The algorithm "reno" is always available, but
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additional choices may be available based on kernel configuration.
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Default is set as part of kernel configuration.
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tcp_dsack - BOOLEAN
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Allows TCP to send "duplicate" SACKs.
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tcp_ecn - BOOLEAN
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Enable Explicit Congestion Notification in TCP.
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tcp_fack - BOOLEAN
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Enable FACK congestion avoidance and fast retransmission.
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The value is not used, if tcp_sack is not enabled.
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tcp_fin_timeout - INTEGER
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Time to hold socket in state FIN-WAIT-2, if it was closed
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by our side. Peer can be broken and never close its side,
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or even died unexpectedly. Default value is 60sec.
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Usual value used in 2.2 was 180 seconds, you may restore
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it, but remember that if your machine is even underloaded WEB server,
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you risk to overflow memory with kilotons of dead sockets,
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FIN-WAIT-2 sockets are less dangerous than FIN-WAIT-1,
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because they eat maximum 1.5K of memory, but they tend
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to live longer. Cf. tcp_max_orphans.
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tcp_frto - INTEGER
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Enables F-RTO, an enhanced recovery algorithm for TCP retransmission
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timeouts. It is particularly beneficial in wireless environments
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where packet loss is typically due to random radio interference
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rather than intermediate router congestion. If set to 1, basic
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version is enabled. 2 enables SACK enhanced F-RTO, which is
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EXPERIMENTAL. The basic version can be used also when SACK is
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enabled for a flow through tcp_sack sysctl.
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tcp_frto_response - INTEGER
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When F-RTO has detected that a TCP retransmission timeout was
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spurious (i.e, the timeout would have been avoided had TCP set a
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longer retransmission timeout), TCP has several options what to do
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next. Possible values are:
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0 Rate halving based; a smooth and conservative response,
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results in halved cwnd and ssthresh after one RTT
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1 Very conservative response; not recommended because even
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though being valid, it interacts poorly with the rest of
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Linux TCP, halves cwnd and ssthresh immediately
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2 Aggressive response; undoes congestion control measures
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that are now known to be unnecessary (ignoring the
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possibility of a lost retransmission that would require
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TCP to be more cautious), cwnd and ssthresh are restored
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to the values prior timeout
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Default: 0 (rate halving based)
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tcp_keepalive_time - INTEGER
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How often TCP sends out keepalive messages when keepalive is enabled.
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Default: 2hours.
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tcp_keepalive_probes - INTEGER
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How many keepalive probes TCP sends out, until it decides that the
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connection is broken. Default value: 9.
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tcp_keepalive_intvl - INTEGER
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How frequently the probes are send out. Multiplied by
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tcp_keepalive_probes it is time to kill not responding connection,
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after probes started. Default value: 75sec i.e. connection
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will be aborted after ~11 minutes of retries.
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tcp_low_latency - BOOLEAN
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If set, the TCP stack makes decisions that prefer lower
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latency as opposed to higher throughput. By default, this
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option is not set meaning that higher throughput is preferred.
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An example of an application where this default should be
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changed would be a Beowulf compute cluster.
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Default: 0
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tcp_max_orphans - INTEGER
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Maximal number of TCP sockets not attached to any user file handle,
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held by system. If this number is exceeded orphaned connections are
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reset immediately and warning is printed. This limit exists
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only to prevent simple DoS attacks, you _must_ not rely on this
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or lower the limit artificially, but rather increase it
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(probably, after increasing installed memory),
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if network conditions require more than default value,
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and tune network services to linger and kill such states
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more aggressively. Let me to remind again: each orphan eats
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up to ~64K of unswappable memory.
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tcp_max_syn_backlog - INTEGER
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Maximal number of remembered connection requests, which are
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still did not receive an acknowledgment from connecting client.
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Default value is 1024 for systems with more than 128Mb of memory,
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and 128 for low memory machines. If server suffers of overload,
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try to increase this number.
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tcp_max_tw_buckets - INTEGER
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Maximal number of timewait sockets held by system simultaneously.
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If this number is exceeded time-wait socket is immediately destroyed
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and warning is printed. This limit exists only to prevent
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simple DoS attacks, you _must_ not lower the limit artificially,
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but rather increase it (probably, after increasing installed memory),
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if network conditions require more than default value.
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tcp_mem - vector of 3 INTEGERs: min, pressure, max
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min: below this number of pages TCP is not bothered about its
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memory appetite.
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pressure: when amount of memory allocated by TCP exceeds this number
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of pages, TCP moderates its memory consumption and enters memory
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pressure mode, which is exited when memory consumption falls
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under "min".
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max: number of pages allowed for queueing by all TCP sockets.
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Defaults are calculated at boot time from amount of available
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memory.
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tcp_moderate_rcvbuf - BOOLEAN
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If set, TCP performs receive buffer autotuning, attempting to
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automatically size the buffer (no greater than tcp_rmem[2]) to
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match the size required by the path for full throughput. Enabled by
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default.
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tcp_mtu_probing - INTEGER
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Controls TCP Packetization-Layer Path MTU Discovery. Takes three
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values:
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0 - Disabled
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1 - Disabled by default, enabled when an ICMP black hole detected
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2 - Always enabled, use initial MSS of tcp_base_mss.
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tcp_no_metrics_save - BOOLEAN
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By default, TCP saves various connection metrics in the route cache
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when the connection closes, so that connections established in the
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near future can use these to set initial conditions. Usually, this
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increases overall performance, but may sometimes cause performance
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degredation. If set, TCP will not cache metrics on closing
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connections.
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tcp_orphan_retries - INTEGER
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How may times to retry before killing TCP connection, closed
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by our side. Default value 7 corresponds to ~50sec-16min
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depending on RTO. If you machine is loaded WEB server,
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you should think about lowering this value, such sockets
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may consume significant resources. Cf. tcp_max_orphans.
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tcp_reordering - INTEGER
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Maximal reordering of packets in a TCP stream.
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Default: 3
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tcp_retrans_collapse - BOOLEAN
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Bug-to-bug compatibility with some broken printers.
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On retransmit try to send bigger packets to work around bugs in
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certain TCP stacks.
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tcp_retries1 - INTEGER
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How many times to retry before deciding that something is wrong
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and it is necessary to report this suspicion to network layer.
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Minimal RFC value is 3, it is default, which corresponds
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to ~3sec-8min depending on RTO.
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tcp_retries2 - INTEGER
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How may times to retry before killing alive TCP connection.
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RFC1122 says that the limit should be longer than 100 sec.
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It is too small number. Default value 15 corresponds to ~13-30min
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depending on RTO.
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tcp_rfc1337 - BOOLEAN
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If set, the TCP stack behaves conforming to RFC1337. If unset,
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we are not conforming to RFC, but prevent TCP TIME_WAIT
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assassination.
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Default: 0
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tcp_rmem - vector of 3 INTEGERs: min, default, max
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min: Minimal size of receive buffer used by TCP sockets.
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It is guaranteed to each TCP socket, even under moderate memory
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pressure.
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Default: 8K
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default: default size of receive buffer used by TCP sockets.
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This value overrides net.core.rmem_default used by other protocols.
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Default: 87380 bytes. This value results in window of 65535 with
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default setting of tcp_adv_win_scale and tcp_app_win:0 and a bit
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less for default tcp_app_win. See below about these variables.
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max: maximal size of receive buffer allowed for automatically
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selected receiver buffers for TCP socket. This value does not override
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net.core.rmem_max, "static" selection via SO_RCVBUF does not use this.
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Default: 87380*2 bytes.
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tcp_sack - BOOLEAN
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Enable select acknowledgments (SACKS).
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tcp_slow_start_after_idle - BOOLEAN
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If set, provide RFC2861 behavior and time out the congestion
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window after an idle period. An idle period is defined at
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the current RTO. If unset, the congestion window will not
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be timed out after an idle period.
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Default: 1
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tcp_stdurg - BOOLEAN
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Use the Host requirements interpretation of the TCP urg pointer field.
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Most hosts use the older BSD interpretation, so if you turn this on
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Linux might not communicate correctly with them.
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Default: FALSE
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tcp_synack_retries - INTEGER
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Number of times SYNACKs for a passive TCP connection attempt will
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be retransmitted. Should not be higher than 255. Default value
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is 5, which corresponds to ~180seconds.
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tcp_syncookies - BOOLEAN
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Only valid when the kernel was compiled with CONFIG_SYNCOOKIES
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Send out syncookies when the syn backlog queue of a socket
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overflows. This is to prevent against the common 'syn flood attack'
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Default: FALSE
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Note, that syncookies is fallback facility.
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It MUST NOT be used to help highly loaded servers to stand
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against legal connection rate. If you see synflood warnings
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in your logs, but investigation shows that they occur
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because of overload with legal connections, you should tune
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another parameters until this warning disappear.
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See: tcp_max_syn_backlog, tcp_synack_retries, tcp_abort_on_overflow.
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syncookies seriously violate TCP protocol, do not allow
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to use TCP extensions, can result in serious degradation
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of some services (f.e. SMTP relaying), visible not by you,
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but your clients and relays, contacting you. While you see
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synflood warnings in logs not being really flooded, your server
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is seriously misconfigured.
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tcp_syn_retries - INTEGER
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Number of times initial SYNs for an active TCP connection attempt
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will be retransmitted. Should not be higher than 255. Default value
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is 5, which corresponds to ~180seconds.
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tcp_timestamps - BOOLEAN
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Enable timestamps as defined in RFC1323.
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tcp_tso_win_divisor - INTEGER
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This allows control over what percentage of the congestion window
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can be consumed by a single TSO frame.
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The setting of this parameter is a choice between burstiness and
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building larger TSO frames.
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Default: 3
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tcp_tw_recycle - BOOLEAN
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Enable fast recycling TIME-WAIT sockets. Default value is 0.
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It should not be changed without advice/request of technical
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experts.
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tcp_tw_reuse - BOOLEAN
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Allow to reuse TIME-WAIT sockets for new connections when it is
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safe from protocol viewpoint. Default value is 0.
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It should not be changed without advice/request of technical
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experts.
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tcp_window_scaling - BOOLEAN
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Enable window scaling as defined in RFC1323.
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tcp_wmem - vector of 3 INTEGERs: min, default, max
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min: Amount of memory reserved for send buffers for TCP socket.
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Each TCP socket has rights to use it due to fact of its birth.
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Default: 4K
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default: Amount of memory allowed for send buffers for TCP socket
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by default. This value overrides net.core.wmem_default used
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by other protocols, it is usually lower than net.core.wmem_default.
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Default: 16K
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max: Maximal amount of memory allowed for automatically selected
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send buffers for TCP socket. This value does not override
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net.core.wmem_max, "static" selection via SO_SNDBUF does not use this.
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Default: 128K
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tcp_workaround_signed_windows - BOOLEAN
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If set, assume no receipt of a window scaling option means the
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remote TCP is broken and treats the window as a signed quantity.
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If unset, assume the remote TCP is not broken even if we do
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not receive a window scaling option from them.
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Default: 0
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CIPSOv4 Variables:
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cipso_cache_enable - BOOLEAN
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If set, enable additions to and lookups from the CIPSO label mapping
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cache. If unset, additions are ignored and lookups always result in a
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miss. However, regardless of the setting the cache is still
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invalidated when required when means you can safely toggle this on and
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off and the cache will always be "safe".
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Default: 1
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cipso_cache_bucket_size - INTEGER
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The CIPSO label cache consists of a fixed size hash table with each
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hash bucket containing a number of cache entries. This variable limits
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the number of entries in each hash bucket; the larger the value the
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more CIPSO label mappings that can be cached. When the number of
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entries in a given hash bucket reaches this limit adding new entries
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causes the oldest entry in the bucket to be removed to make room.
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Default: 10
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cipso_rbm_optfmt - BOOLEAN
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Enable the "Optimized Tag 1 Format" as defined in section 3.4.2.6 of
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the CIPSO draft specification (see Documentation/netlabel for details).
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This means that when set the CIPSO tag will be padded with empty
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categories in order to make the packet data 32-bit aligned.
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Default: 0
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cipso_rbm_structvalid - BOOLEAN
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If set, do a very strict check of the CIPSO option when
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ip_options_compile() is called. If unset, relax the checks done during
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ip_options_compile(). Either way is "safe" as errors are caught else
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where in the CIPSO processing code but setting this to 0 (False) should
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result in less work (i.e. it should be faster) but could cause problems
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with other implementations that require strict checking.
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Default: 0
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IP Variables:
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ip_local_port_range - 2 INTEGERS
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Defines the local port range that is used by TCP and UDP to
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choose the local port. The first number is the first, the
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second the last local port number. Default value depends on
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amount of memory available on the system:
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> 128Mb 32768-61000
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< 128Mb 1024-4999 or even less.
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This number defines number of active connections, which this
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system can issue simultaneously to systems not supporting
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TCP extensions (timestamps). With tcp_tw_recycle enabled
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(i.e. by default) range 1024-4999 is enough to issue up to
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2000 connections per second to systems supporting timestamps.
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|
|
|
ip_nonlocal_bind - BOOLEAN
|
|
If set, allows processes to bind() to non-local IP addresses,
|
|
which can be quite useful - but may break some applications.
|
|
Default: 0
|
|
|
|
ip_dynaddr - BOOLEAN
|
|
If set non-zero, enables support for dynamic addresses.
|
|
If set to a non-zero value larger than 1, a kernel log
|
|
message will be printed when dynamic address rewriting
|
|
occurs.
|
|
Default: 0
|
|
|
|
icmp_echo_ignore_all - BOOLEAN
|
|
If set non-zero, then the kernel will ignore all ICMP ECHO
|
|
requests sent to it.
|
|
Default: 0
|
|
|
|
icmp_echo_ignore_broadcasts - BOOLEAN
|
|
If set non-zero, then the kernel will ignore all ICMP ECHO and
|
|
TIMESTAMP requests sent to it via broadcast/multicast.
|
|
Default: 1
|
|
|
|
icmp_ratelimit - INTEGER
|
|
Limit the maximal rates for sending ICMP packets whose type matches
|
|
icmp_ratemask (see below) to specific targets.
|
|
0 to disable any limiting, otherwise the maximal rate in jiffies(1)
|
|
Default: 100
|
|
|
|
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
|
|
Some routers violate RFC1122 by sending bogus responses to broadcast
|
|
frames. Such violations are normally logged via a kernel warning.
|
|
If this is set to TRUE, the kernel will not give such warnings, which
|
|
will avoid log file clutter.
|
|
Default: FALSE
|
|
|
|
icmp_errors_use_inbound_ifaddr - BOOLEAN
|
|
|
|
If zero, icmp error messages are sent with the primary address of
|
|
the exiting interface.
|
|
|
|
If non-zero, the message will be sent with the primary address of
|
|
the interface that received the packet that caused the icmp error.
|
|
This is the behaviour 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.
|
|
|
|
Default: 0
|
|
|
|
igmp_max_memberships - INTEGER
|
|
Change the maximum number of multicast groups we can subscribe to.
|
|
Default: 20
|
|
|
|
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
|
|
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
|
|
default TRUE
|
|
|
|
secure_redirects - BOOLEAN
|
|
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
|
|
default TRUE
|
|
|
|
send_redirects - BOOLEAN
|
|
Send redirects, if router.
|
|
send_redirects for the interface will be enabled if at least one of
|
|
conf/{all,interface}/send_redirects is set to TRUE,
|
|
it will be disabled otherwise
|
|
Default: TRUE
|
|
|
|
bootp_relay - BOOLEAN
|
|
Accept packets with source address 0.b.c.d destined
|
|
not to this host as local ones. It is supposed, that
|
|
BOOTP relay daemon will catch and forward such packets.
|
|
conf/all/bootp_relay must also be set to TRUE to enable BOOTP relay
|
|
for the interface
|
|
default FALSE
|
|
Not Implemented Yet.
|
|
|
|
accept_source_route - BOOLEAN
|
|
Accept packets with SRR option.
|
|
conf/all/accept_source_route must also be set to TRUE to accept packets
|
|
with SRR option on the interface
|
|
default TRUE (router)
|
|
FALSE (host)
|
|
|
|
rp_filter - BOOLEAN
|
|
1 - 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.
|
|
|
|
0 - 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.
|
|
|
|
0 - (default) The kernel can respond to arp requests with addresses
|
|
from other interfaces. This may seem wrong but it usually makes
|
|
sense, because it increases the chance of successful communication.
|
|
IP addresses are owned by the complete host on Linux, not by
|
|
particular interfaces. Only for more complex setups like load-
|
|
balancing, does this behaviour cause problems.
|
|
|
|
arp_filter for the interface will be enabled if at least one of
|
|
conf/{all,interface}/arp_filter is set to TRUE,
|
|
it will be disabled otherwise
|
|
|
|
arp_announce - INTEGER
|
|
Define different restriction levels for announcing the local
|
|
source IP address from IP packets in ARP requests sent on
|
|
interface:
|
|
0 - (default) Use any local address, configured on any interface
|
|
1 - Try to avoid local addresses that are not in the target's
|
|
subnet for this interface. This mode is useful when target
|
|
hosts reachable via this interface require the source IP
|
|
address in ARP requests to be part of their logical network
|
|
configured on the receiving interface. When we generate the
|
|
request we will check all our subnets that include the
|
|
target IP and will preserve the source address if it is from
|
|
such subnet. If there is no such subnet we select source
|
|
address according to the rules for level 2.
|
|
2 - Always use the best local address for this target.
|
|
In this mode we ignore the source address in the IP packet
|
|
and try to select local address that we prefer for talks with
|
|
the target host. Such local address is selected by looking
|
|
for primary IP addresses on all our subnets on the outgoing
|
|
interface that include the target IP address. If no suitable
|
|
local address is found we select the first local address
|
|
we have on the outgoing interface or on all other interfaces,
|
|
with the hope we will receive reply for our request and
|
|
even sometimes no matter the source IP address we announce.
|
|
|
|
The max value from conf/{all,interface}/arp_announce is used.
|
|
|
|
Increasing the restriction level gives more chance for
|
|
receiving answer from the resolved target while decreasing
|
|
the level announces more valid sender's information.
|
|
|
|
arp_ignore - INTEGER
|
|
Define different modes for sending replies in response to
|
|
received ARP requests that resolve local target IP addresses:
|
|
0 - (default): reply for any local target IP address, configured
|
|
on any interface
|
|
1 - reply only if the target IP address is local address
|
|
configured on the incoming interface
|
|
2 - reply only if the target IP address is local address
|
|
configured on the incoming interface and both with the
|
|
sender's IP address are part from same subnet on this interface
|
|
3 - do not reply for local addresses configured with scope host,
|
|
only resolutions for global and link addresses are replied
|
|
4-7 - reserved
|
|
8 - do not reply for all local addresses
|
|
|
|
The max value from conf/{all,interface}/arp_ignore is used
|
|
when ARP request is received on the {interface}
|
|
|
|
arp_accept - BOOLEAN
|
|
Define behavior when gratuitous arp replies are received:
|
|
0 - drop gratuitous arp frames
|
|
1 - 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.
|
|
|
|
(1) Jiffie: internal timeunit for the kernel. On the i386 1/100s, on the
|
|
Alpha 1/1024s. See the HZ define in /usr/include/asm/param.h for the exact
|
|
value on your system.
|
|
|
|
Alexey Kuznetsov.
|
|
kuznet@ms2.inr.ac.ru
|
|
|
|
Updated by:
|
|
Andi Kleen
|
|
ak@muc.de
|
|
Nicolas Delon
|
|
delon.nicolas@wanadoo.fr
|
|
|
|
|
|
|
|
|
|
/proc/sys/net/ipv6/* Variables:
|
|
|
|
IPv6 has no global variables such as tcp_*. tcp_* settings under ipv4/ also
|
|
apply to IPv6 [XXX?].
|
|
|
|
bindv6only - BOOLEAN
|
|
Default value for IPV6_V6ONLY socket option,
|
|
which restricts use of the IPv6 socket to IPv6 communication
|
|
only.
|
|
TRUE: disable IPv4-mapped address feature
|
|
FALSE: enable IPv4-mapped address feature
|
|
|
|
Default: FALSE (as specified in 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.
|
|
|
|
[XXX: Other special features than forwarding?]
|
|
|
|
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.
|
|
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.
|
|
|
|
accept_source_route - INTEGER
|
|
Accept source routing (routing extension header).
|
|
|
|
> 0: Accept routing header.
|
|
= 0: Accept only routing header type 2.
|
|
< 0: Do not accept routing header.
|
|
|
|
Default: 0
|
|
|
|
autoconf - BOOLEAN
|
|
Autoconfigure addresses using Prefix Information in Router
|
|
Advertisements.
|
|
|
|
Functional default: enabled if accept_ra_pinfo is enabled.
|
|
disabled if accept_ra_pinfo is disabled.
|
|
|
|
dad_transmits - INTEGER
|
|
The amount of Duplicate Address Detection probes to send.
|
|
Default: 1
|
|
|
|
forwarding - 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 to disable any limiting, otherwise the maximal rate in jiffies(1)
|
|
Default: 100
|
|
|
|
|
|
IPv6 Update by:
|
|
Pekka Savola <pekkas@netcore.fi>
|
|
YOSHIFUJI Hideaki / USAGI Project <yoshfuji@linux-ipv6.org>
|
|
|
|
|
|
/proc/sys/net/bridge/* Variables:
|
|
|
|
bridge-nf-call-arptables - BOOLEAN
|
|
1 : pass bridged ARP traffic to arptables' FORWARD chain.
|
|
0 : disable this.
|
|
Default: 1
|
|
|
|
bridge-nf-call-iptables - BOOLEAN
|
|
1 : pass bridged IPv4 traffic to iptables' chains.
|
|
0 : disable this.
|
|
Default: 1
|
|
|
|
bridge-nf-call-ip6tables - BOOLEAN
|
|
1 : pass bridged IPv6 traffic to ip6tables' chains.
|
|
0 : disable this.
|
|
Default: 1
|
|
|
|
bridge-nf-filter-vlan-tagged - BOOLEAN
|
|
1 : pass bridged vlan-tagged ARP/IP/IPv6 traffic to {arp,ip,ip6}tables.
|
|
0 : disable this.
|
|
Default: 1
|
|
|
|
bridge-nf-filter-pppoe-tagged - BOOLEAN
|
|
1 : pass bridged pppoe-tagged IP/IPv6 traffic to {ip,ip6}tables.
|
|
0 : disable this.
|
|
Default: 1
|
|
|
|
|
|
UNDOCUMENTED:
|
|
|
|
dev_weight FIXME
|
|
discovery_slots FIXME
|
|
discovery_timeout FIXME
|
|
fast_poll_increase FIXME
|
|
ip6_queue_maxlen FIXME
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lap_keepalive_time FIXME
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lo_cong FIXME
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max_baud_rate FIXME
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max_dgram_qlen FIXME
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max_noreply_time FIXME
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max_tx_data_size FIXME
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max_tx_window FIXME
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min_tx_turn_time FIXME
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mod_cong FIXME
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no_cong FIXME
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no_cong_thresh FIXME
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slot_timeout FIXME
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warn_noreply_time FIXME
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