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Documentation/networking/ip-sysctl.txt
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/proc/sys/net/ipv4/* Variables: ip_forward - BOOLEAN 0 - disabled (default) |
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not 0 - enabled |
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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 |
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Default value of TTL field (Time To Live) for outgoing (but not forwarded) IP packets. Should be between 1 and 255 inclusive. Default: 64 (as recommended by RFC1700) |
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ip_no_pmtu_disc - INTEGER Disable Path MTU Discovery. If enabled in mode 1 and a |
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fragmentation-required ICMP is received, the PMTU to this destination will be set to min_pmtu (see below). You will need to raise min_pmtu to the smallest interface MTU on your system manually if you want to avoid locally generated fragments. |
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In mode 2 incoming Path MTU Discovery messages will be discarded. Outgoing frames are handled the same as in mode 1, implicitly setting IP_PMTUDISC_DONT on every created socket. |
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Mode 3 is a hardend pmtu discover mode. The kernel will only accept fragmentation-needed errors if the underlying protocol can verify them besides a plain socket lookup. Current protocols for which pmtu events will be honored are TCP, SCTP and DCCP as they verify e.g. the sequence number or the association. This mode should not be enabled globally but is only intended to secure e.g. name servers in namespaces where TCP path mtu must still work but path MTU information of other protocols should be discarded. If enabled globally this mode could break other protocols. Possible values: 0-3 |
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Default: FALSE |
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min_pmtu - INTEGER |
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default 552 - minimum discovered Path MTU |
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ip_forward_use_pmtu - BOOLEAN By default we don't trust protocol path MTUs while forwarding because they could be easily forged and can lead to unwanted fragmentation by the router. You only need to enable this if you have user-space software which tries to discover path mtus by itself and depends on the kernel honoring this information. This is normally not the case. Default: 0 (disabled) Possible values: 0 - disabled 1 - enabled |
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fwmark_reflect - BOOLEAN Controls the fwmark of kernel-generated IPv4 reply packets that are not associated with a socket for example, TCP RSTs or ICMP echo replies). If unset, these packets have a fwmark of zero. If set, they have the fwmark of the packet they are replying to. Default: 0 |
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fib_multipath_use_neigh - BOOLEAN Use status of existing neighbor entry when determining nexthop for multipath routes. If disabled, neighbor information is not used and packets could be directed to a failed nexthop. Only valid for kernels built with CONFIG_IP_ROUTE_MULTIPATH enabled. Default: 0 (disabled) Possible values: 0 - disabled 1 - enabled |
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route/max_size - INTEGER Maximum number of routes allowed in the kernel. Increase this when using large numbers of interfaces and/or routes. |
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From linux kernel 3.6 onwards, this is deprecated for ipv4 as route cache is no longer used. |
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neigh/default/gc_thresh1 - INTEGER Minimum number of entries to keep. Garbage collector will not purge entries if there are fewer than this number. |
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Default: 128 |
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neigh/default/gc_thresh2 - INTEGER Threshold when garbage collector becomes more aggressive about purging entries. Entries older than 5 seconds will be cleared when over this number. Default: 512 |
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neigh/default/gc_thresh3 - INTEGER Maximum number of neighbor entries allowed. Increase this when using large numbers of interfaces and when communicating with large numbers of directly-connected peers. |
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Default: 1024 |
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neigh/default/unres_qlen_bytes - INTEGER The maximum number of bytes which may be used by packets queued for each unresolved address by other network layers. (added in linux 3.3) |
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Setting negative value is meaningless and will return error. |
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Default: 65536 Bytes(64KB) |
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neigh/default/unres_qlen - INTEGER The maximum number of packets which may be queued for each unresolved address by other network layers. (deprecated in linux 3.3) : use unres_qlen_bytes instead. |
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Prior to linux 3.3, the default value is 3 which may cause |
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unexpected packet loss. The current default value is calculated |
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according to default value of unres_qlen_bytes and true size of packet. Default: 31 |
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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 |
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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, the fragment handler will toss packets until ipfrag_low_thresh |
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is reached. This also serves as a maximum limit to namespaces different from the initial one. |
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ipfrag_low_thresh - INTEGER |
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Maximum memory used to reassemble IP fragments before the kernel begins to remove incomplete fragment queues to free up resources. The kernel still accepts new fragments for defragmentation. |
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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_max_dist - INTEGER |
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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 |
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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 |
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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 |
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from different IP datagrams, which could result in data corruption. Default: 64 |
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INET peer storage: 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 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. |
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Measured in seconds. |
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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). |
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Measured in seconds. |
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TCP variables: |
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somaxconn - INTEGER Limit of socket listen() backlog, known in userspace as SOMAXCONN. Defaults to 128. See also tcp_max_syn_backlog for additional tuning for TCP sockets. |
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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. |
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tcp_adv_win_scale - INTEGER Count buffering overhead as bytes/2^tcp_adv_win_scale (if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale), if it is <= 0. |
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Possible values are [-31, 31], inclusive. |
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Default: 1 |
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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. Default is "reno" and the default setting (tcp_congestion_control). |
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tcp_app_win - INTEGER Reserve max(window/2^tcp_app_win, mss) of window for application buffer. Value 0 is special, it means that nothing is reserved. Default: 31 |
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tcp_autocorking - BOOLEAN Enable TCP auto corking : When applications do consecutive small write()/sendmsg() system calls, we try to coalesce these small writes as much as possible, to lower total amount of sent packets. This is done if at least one prior packet for the flow is waiting in Qdisc queues or device transmit queue. Applications can still use TCP_CORK for optimal behavior when they know how/when to uncork their sockets. Default : 1 |
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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. |
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tcp_base_mss - INTEGER |
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The initial value of search_low to be used by the packetization layer Path MTU discovery (MTU probing). If MTU probing is enabled, this is the initial MSS used by the connection. |
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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. Default is set as part of kernel configuration. |
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For passive connections, the listener congestion control choice is inherited. [see setsockopt(listenfd, SOL_TCP, TCP_CONGESTION, "name" ...) ] |
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tcp_dsack - BOOLEAN Allows TCP to send "duplicate" SACKs. |
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tcp_early_retrans - INTEGER Enable Early Retransmit (ER), per RFC 5827. ER lowers the threshold for triggering fast retransmit when the amount of outstanding data is small and when no previously unsent data can be transmitted (such |
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that limited transmit could be used). Also controls the use of |
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Tail loss probe (TLP) that converts RTOs occurring due to tail |
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losses into fast recovery (draft-dukkipati-tcpm-tcp-loss-probe-01). |
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Possible values: 0 disables ER 1 enables ER 2 enables ER but delays fast recovery and fast retransmit by a fourth of RTT. This mitigates connection falsely recovers when network has a small degree of reordering (less than 3 packets). |
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3 enables delayed ER and TLP. 4 enables TLP only. Default: 3 |
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tcp_ecn - INTEGER |
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Control use of Explicit Congestion Notification (ECN) by TCP. ECN is used only when both ends of the TCP connection indicate support for it. This feature is useful in avoiding losses due to congestion by allowing supporting routers to signal congestion before having to drop packets. |
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Possible values are: |
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0 Disable ECN. Neither initiate nor accept ECN. |
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1 Enable ECN when requested by incoming connections and also request ECN on outgoing connection attempts. 2 Enable ECN when requested by incoming connections |
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but do not request ECN on outgoing connections. |
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Default: 2 |
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tcp_ecn_fallback - BOOLEAN If the kernel detects that ECN connection misbehaves, enable fall back to non-ECN. Currently, this knob implements the fallback from RFC3168, section 6.1.1.1., but we reserve that in future, additional detection mechanisms could be implemented under this knob. The value is not used, if tcp_ecn or per route (or congestion control) ECN settings are disabled. Default: 1 (fallback enabled) |
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tcp_fack - BOOLEAN Enable FACK congestion avoidance and fast retransmission. The value is not used, if tcp_sack is not enabled. |
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tcp_fin_timeout - INTEGER |
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The length of time an orphaned (no longer referenced by any application) connection will remain in the FIN_WAIT_2 state before it is aborted at the local end. While a perfectly valid "receive only" state for an un-orphaned connection, an orphaned connection in FIN_WAIT_2 state could otherwise wait forever for the remote to close its end of the connection. Cf. tcp_max_orphans Default: 60 seconds |
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tcp_frto - INTEGER |
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Enables Forward RTO-Recovery (F-RTO) defined in RFC5682. |
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F-RTO is an enhanced recovery algorithm for TCP retransmission |
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timeouts. It is particularly beneficial in networks where the RTT fluctuates (e.g., wireless). F-RTO is sender-side only modification. It does not require any support from the peer. By default it's enabled with a non-zero value. 0 disables F-RTO. |
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tcp_invalid_ratelimit - INTEGER Limit the maximal rate for sending duplicate acknowledgments in response to incoming TCP packets that are for an existing connection but that are invalid due to any of these reasons: (a) out-of-window sequence number, (b) out-of-window acknowledgment number, or (c) PAWS (Protection Against Wrapped Sequence numbers) check failure This can help mitigate simple "ack loop" DoS attacks, wherein a buggy or malicious middlebox or man-in-the-middle can rewrite TCP header fields in manner that causes each endpoint to think that the other is sending invalid TCP segments, thus causing each side to send an unterminating stream of duplicate acknowledgments for invalid segments. Using 0 disables rate-limiting of dupacks in response to invalid segments; otherwise this value specifies the minimal space between sending such dupacks, in milliseconds. Default: 500 (milliseconds). |
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tcp_keepalive_time - INTEGER How often TCP sends out keepalive messages when keepalive is enabled. Default: 2hours. |
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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 How frequently the probes are send out. Multiplied by tcp_keepalive_probes it is time to kill not responding connection, after probes started. Default value: 75sec i.e. connection will be aborted after ~11 minutes of retries. |
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tcp_l3mdev_accept - BOOLEAN Enables child sockets to inherit the L3 master device index. Enabling this option allows a "global" listen socket to work across L3 master domains (e.g., VRFs) with connected sockets derived from the listen socket to be bound to the L3 domain in which the packets originated. Only valid when the kernel was compiled with CONFIG_NET_L3_MASTER_DEV. |
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tcp_low_latency - BOOLEAN 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. Default: 0 |
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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. |
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tcp_max_syn_backlog - INTEGER |
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Maximal number of remembered connection requests, which have not received an acknowledgment from connecting client. The minimal value is 128 for low memory machines, and it will increase in proportion to the memory of machine. If server suffers from overload, try increasing this number. |
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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. |
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tcp_mem - vector of 3 INTEGERs: min, pressure, max min: below this number of pages TCP is not bothered about its memory appetite. |
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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". |
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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 memory. |
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tcp_min_rtt_wlen - INTEGER The window length of the windowed min filter to track the minimum RTT. A shorter window lets a flow more quickly pick up new (higher) minimum RTT when it is moved to a longer path (e.g., due to traffic engineering). A longer window makes the filter more resistant to RTT inflations such as transient congestion. The unit is seconds. Default: 300 |
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tcp_moderate_rcvbuf - BOOLEAN |
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If set, TCP performs receive buffer auto-tuning, attempting to |
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automatically size the buffer (no greater than tcp_rmem[2]) to match the size required by the path for full throughput. Enabled by default. tcp_mtu_probing - INTEGER Controls TCP Packetization-Layer Path MTU Discovery. Takes three values: 0 - Disabled 1 - Disabled by default, enabled when an ICMP black hole detected 2 - Always enabled, use initial MSS of tcp_base_mss. |
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tcp_probe_interval - INTEGER Controls how often to start TCP Packetization-Layer Path MTU Discovery reprobe. The default is reprobing every 10 minutes as per RFC4821. tcp_probe_threshold - INTEGER Controls when TCP Packetization-Layer Path MTU Discovery probing will stop in respect to the width of search range in bytes. Default is 8 bytes. |
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tcp_no_metrics_save - BOOLEAN By default, TCP saves various connection metrics in the route cache when the connection closes, so that connections established in the near future can use these to set initial conditions. Usually, this increases overall performance, but may sometimes cause performance |
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degradation. 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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This value influences the timeout of a locally closed TCP connection, when RTO retransmissions remain unacknowledged. See tcp_retries2 for more details. |
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The default value is 8. |
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If your machine is a loaded WEB server, |
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you should think about lowering this value, such sockets may consume significant resources. Cf. tcp_max_orphans. |
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tcp_recovery - INTEGER This value is a bitmap to enable various experimental loss recovery features. RACK: 0x1 enables the RACK loss detection for fast detection of lost retransmissions and tail drops. Default: 0x1 |
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tcp_reordering - INTEGER |
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Initial reordering level of packets in a TCP stream. TCP stack can then dynamically adjust flow reordering level between this initial value and tcp_max_reordering |
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Default: 3 |
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tcp_max_reordering - INTEGER Maximal reordering level of packets in a TCP stream. 300 is a fairly conservative value, but you might increase it if paths are using per packet load balancing (like bonding rr mode) Default: 300 |
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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. |
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tcp_retries1 - INTEGER |
5d7892298 RTO connection ti... |
460 461 462 463 464 465 466 |
This value influences the time, after which TCP decides, that something is wrong due to unacknowledged RTO retransmissions, and reports this suspicion to the network layer. See tcp_retries2 for more details. RFC 1122 recommends at least 3 retransmissions, which is the default. |
1da177e4c Linux-2.6.12-rc2 |
467 |
|
ef56e622c [NET] ip-sysctl.t... |
468 |
tcp_retries2 - INTEGER |
5d7892298 RTO connection ti... |
469 470 471 472 473 474 475 476 477 478 479 480 481 |
This value influences the timeout of an alive TCP connection, when RTO retransmissions remain unacknowledged. Given a value of N, a hypothetical TCP connection following exponential backoff with an initial RTO of TCP_RTO_MIN would retransmit N times before killing the connection at the (N+1)th RTO. The default value of 15 yields a hypothetical timeout of 924.6 seconds and is a lower bound for the effective timeout. TCP will effectively time out at the first RTO which exceeds the hypothetical timeout. RFC 1122 recommends at least 100 seconds for the timeout, which corresponds to a value of at least 8. |
1da177e4c Linux-2.6.12-rc2 |
482 |
|
ef56e622c [NET] ip-sysctl.t... |
483 484 485 486 487 |
tcp_rfc1337 - BOOLEAN If set, the TCP stack behaves conforming to RFC1337. If unset, we are not conforming to RFC, but prevent TCP TIME_WAIT assassination. Default: 0 |
1da177e4c Linux-2.6.12-rc2 |
488 489 490 491 492 |
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. |
6539fefd9 Update documented... |
493 |
Default: 1 page |
1da177e4c Linux-2.6.12-rc2 |
494 |
|
53025f5ef Documentation: cl... |
495 |
default: initial size of receive buffer used by TCP sockets. |
1da177e4c Linux-2.6.12-rc2 |
496 497 498 499 500 501 502 |
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 |
53025f5ef Documentation: cl... |
503 504 505 |
net.core.rmem_max. Calling setsockopt() with SO_RCVBUF disables automatic tuning of that socket's receive buffer size, in which case this value is ignored. |
b49960a05 tcp: change tcp_a... |
506 |
Default: between 87380B and 6MB, depending on RAM size. |
1da177e4c Linux-2.6.12-rc2 |
507 |
|
ef56e622c [NET] ip-sysctl.t... |
508 509 |
tcp_sack - BOOLEAN Enable select acknowledgments (SACKS). |
1da177e4c Linux-2.6.12-rc2 |
510 |
|
ef56e622c [NET] ip-sysctl.t... |
511 512 513 514 515 516 |
tcp_slow_start_after_idle - BOOLEAN 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. Default: 1 |
1da177e4c Linux-2.6.12-rc2 |
517 |
|
ef56e622c [NET] ip-sysctl.t... |
518 |
tcp_stdurg - BOOLEAN |
4edc2f341 ip: sysctl docume... |
519 |
Use the Host requirements interpretation of the TCP urgent pointer field. |
ef56e622c [NET] ip-sysctl.t... |
520 521 522 |
Most hosts use the older BSD interpretation, so if you turn this on Linux might not communicate correctly with them. Default: FALSE |
1da177e4c Linux-2.6.12-rc2 |
523 |
|
ef56e622c [NET] ip-sysctl.t... |
524 525 526 |
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 |
6c9ff979d tcp: Increase tim... |
527 528 529 |
is 5, which corresponds to 31seconds till the last retransmission with the current initial RTO of 1second. With this the final timeout for a passive TCP connection will happen after 63seconds. |
1da177e4c Linux-2.6.12-rc2 |
530 |
|
ef56e622c [NET] ip-sysctl.t... |
531 |
tcp_syncookies - BOOLEAN |
a3c910d2e tcp: doc : fix th... |
532 |
Only valid when the kernel was compiled with CONFIG_SYN_COOKIES |
ef56e622c [NET] ip-sysctl.t... |
533 |
Send out syncookies when the syn backlog queue of a socket |
4edc2f341 ip: sysctl docume... |
534 |
overflows. This is to prevent against the common 'SYN flood attack' |
a3c910d2e tcp: doc : fix th... |
535 |
Default: 1 |
1da177e4c Linux-2.6.12-rc2 |
536 |
|
ef56e622c [NET] ip-sysctl.t... |
537 538 |
Note, that syncookies is fallback facility. It MUST NOT be used to help highly loaded servers to stand |
4edc2f341 ip: sysctl docume... |
539 |
against legal connection rate. If you see SYN flood warnings |
ef56e622c [NET] ip-sysctl.t... |
540 541 542 543 |
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. |
1da177e4c Linux-2.6.12-rc2 |
544 |
|
ef56e622c [NET] ip-sysctl.t... |
545 546 547 548 |
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 |
4edc2f341 ip: sysctl docume... |
549 |
SYN flood warnings in logs not being really flooded, your server |
ef56e622c [NET] ip-sysctl.t... |
550 |
is seriously misconfigured. |
1da177e4c Linux-2.6.12-rc2 |
551 |
|
5ad37d5de tcp: add tcp_sync... |
552 553 554 |
If you want to test which effects syncookies have to your network connections you can set this knob to 2 to enable unconditionally generation of syncookies. |
cf60af03c net-tcp: Fast Ope... |
555 |
tcp_fastopen - INTEGER |
cebc5cbab net-tcp: retire T... |
556 557 |
Enable TCP Fast Open (RFC7413) to send and accept data in the opening SYN packet. |
104671636 tcp: TCP Fast Ope... |
558 |
|
cebc5cbab net-tcp: retire T... |
559 560 561 |
The client support is enabled by flag 0x1 (on by default). The client then must use sendmsg() or sendto() with the MSG_FASTOPEN flag, rather than connect() to send data in SYN. |
cf60af03c net-tcp: Fast Ope... |
562 |
|
cebc5cbab net-tcp: retire T... |
563 564 565 566 |
The server support is enabled by flag 0x2 (off by default). Then either enable for all listeners with another flag (0x400) or enable individual listeners via TCP_FASTOPEN socket option with the option value being the length of the syn-data backlog. |
cf60af03c net-tcp: Fast Ope... |
567 |
|
cebc5cbab net-tcp: retire T... |
568 569 570 571 572 573 574 575 576 577 578 579 |
The values (bitmap) are 0x1: (client) enables sending data in the opening SYN on the client. 0x2: (server) enables the server support, i.e., allowing data in a SYN packet to be accepted and passed to the application before 3-way handshake finishes. 0x4: (client) send data in the opening SYN regardless of cookie availability and without a cookie option. 0x200: (server) accept data-in-SYN w/o any cookie option present. 0x400: (server) enable all listeners to support Fast Open by default without explicit TCP_FASTOPEN socket option. Default: 0x1 |
104671636 tcp: TCP Fast Ope... |
580 |
|
cebc5cbab net-tcp: retire T... |
581 582 |
Note that that additional client or server features are only effective if the basic support (0x1 and 0x2) are enabled respectively. |
104671636 tcp: TCP Fast Ope... |
583 |
|
ef56e622c [NET] ip-sysctl.t... |
584 585 |
tcp_syn_retries - INTEGER Number of times initial SYNs for an active TCP connection attempt |
bffae6975 net: change tcp_s... |
586 |
will be retransmitted. Should not be higher than 127. Default value |
3b09adcb2 ip-sysctl: fix sp... |
587 |
is 6, which corresponds to 63seconds till the last retransmission |
6c9ff979d tcp: Increase tim... |
588 589 |
with the current initial RTO of 1second. With this the final timeout for an active TCP connection attempt will happen after 127seconds. |
ef56e622c [NET] ip-sysctl.t... |
590 591 592 |
tcp_timestamps - BOOLEAN Enable timestamps as defined in RFC1323. |
1da177e4c Linux-2.6.12-rc2 |
593 |
|
95bd09eb2 tcp: TSO packets ... |
594 595 596 597 598 599 600 601 |
tcp_min_tso_segs - INTEGER Minimal number of segments per TSO frame. Since linux-3.12, TCP does an automatic sizing of TSO frames, depending on flow rate, instead of filling 64Kbytes packets. For specific usages, it's possible to force TCP to build big TSO frames. Note that TCP stack might split too big TSO packets if available window is too small. Default: 2 |
43e122b01 tcp: refine pacin... |
602 603 604 605 606 607 608 609 610 611 612 613 614 615 |
tcp_pacing_ss_ratio - INTEGER sk->sk_pacing_rate is set by TCP stack using a ratio applied to current rate. (current_rate = cwnd * mss / srtt) If TCP is in slow start, tcp_pacing_ss_ratio is applied to let TCP probe for bigger speeds, assuming cwnd can be doubled every other RTT. Default: 200 tcp_pacing_ca_ratio - INTEGER sk->sk_pacing_rate is set by TCP stack using a ratio applied to current rate. (current_rate = cwnd * mss / srtt) If TCP is in congestion avoidance phase, tcp_pacing_ca_ratio is applied to conservatively probe for bigger throughput. Default: 120 |
1da177e4c Linux-2.6.12-rc2 |
616 |
tcp_tso_win_divisor - INTEGER |
ef56e622c [NET] ip-sysctl.t... |
617 618 619 620 621 |
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. Default: 3 |
1da177e4c Linux-2.6.12-rc2 |
622 |
|
ef56e622c [NET] ip-sysctl.t... |
623 624 625 626 |
tcp_tw_recycle - BOOLEAN Enable fast recycling TIME-WAIT sockets. Default value is 0. It should not be changed without advice/request of technical experts. |
1da177e4c Linux-2.6.12-rc2 |
627 |
|
ef56e622c [NET] ip-sysctl.t... |
628 629 630 631 632 |
tcp_tw_reuse - BOOLEAN Allow to reuse TIME-WAIT sockets for new connections when it is safe from protocol viewpoint. Default value is 0. It should not be changed without advice/request of technical experts. |
ce7bc3bf1 [TCP]: Restrict c... |
633 |
|
ef56e622c [NET] ip-sysctl.t... |
634 635 |
tcp_window_scaling - BOOLEAN Enable window scaling as defined in RFC1323. |
3ff825b28 [TCP]: Add tcp_av... |
636 |
|
ef56e622c [NET] ip-sysctl.t... |
637 |
tcp_wmem - vector of 3 INTEGERs: min, default, max |
53025f5ef Documentation: cl... |
638 |
min: Amount of memory reserved for send buffers for TCP sockets. |
ef56e622c [NET] ip-sysctl.t... |
639 |
Each TCP socket has rights to use it due to fact of its birth. |
6539fefd9 Update documented... |
640 |
Default: 1 page |
9d7bcfc6b [TCP]: Update sys... |
641 |
|
53025f5ef Documentation: cl... |
642 643 644 |
default: initial size of send buffer used by TCP sockets. This value overrides net.core.wmem_default used by other protocols. It is usually lower than net.core.wmem_default. |
ef56e622c [NET] ip-sysctl.t... |
645 |
Default: 16K |
53025f5ef Documentation: cl... |
646 647 648 649 650 651 |
max: Maximal amount of memory allowed for automatically tuned send buffers for TCP sockets. This value does not override net.core.wmem_max. Calling setsockopt() with SO_SNDBUF disables automatic tuning of that socket's send buffer size, in which case this value is ignored. Default: between 64K and 4MB, depending on RAM size. |
1da177e4c Linux-2.6.12-rc2 |
652 |
|
c9bee3b7f tcp: TCP_NOTSENT_... |
653 654 655 656 657 658 659 660 661 662 663 664 |
tcp_notsent_lowat - UNSIGNED INTEGER A TCP socket can control the amount of unsent bytes in its write queue, thanks to TCP_NOTSENT_LOWAT socket option. poll()/select()/epoll() reports POLLOUT events if the amount of unsent bytes is below a per socket value, and if the write queue is not full. sendmsg() will also not add new buffers if the limit is hit. This global variable controls the amount of unsent data for sockets not using TCP_NOTSENT_LOWAT. For these sockets, a change to the global variable has immediate effect. Default: UINT_MAX (0xFFFFFFFF) |
15d99e02b [TCP]: sysctl to ... |
665 666 667 668 669 670 |
tcp_workaround_signed_windows - BOOLEAN 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. Default: 0 |
36e31b0af net: TCP thin lin... |
671 672 673 674 675 676 677 678 679 680 681 |
tcp_thin_linear_timeouts - BOOLEAN Enable dynamic triggering of linear timeouts for thin streams. If set, a check is performed upon retransmission by timeout to determine if the stream is thin (less than 4 packets in flight). As long as the stream is found to be thin, up to 6 linear timeouts may be performed before exponential backoff mode is initiated. This improves retransmission latency for non-aggressive thin streams, often found to be time-dependent. For more information on thin streams, see Documentation/networking/tcp-thin.txt Default: 0 |
7e3801755 net: TCP thin dupack |
682 683 684 685 686 687 688 689 690 691 692 |
tcp_thin_dupack - BOOLEAN Enable dynamic triggering of retransmissions after one dupACK for thin streams. If set, a check is performed upon reception of a dupACK to determine if the stream is thin (less than 4 packets in flight). As long as the stream is found to be thin, data is retransmitted on the first received dupACK. This improves retransmission latency for non-aggressive thin streams, often found to be time-dependent. For more information on thin streams, see Documentation/networking/tcp-thin.txt Default: 0 |
46d3ceabd tcp: TCP Small Qu... |
693 694 695 696 697 698 699 700 701 |
tcp_limit_output_bytes - INTEGER Controls TCP Small Queue limit per tcp socket. TCP bulk sender tends to increase packets in flight until it gets losses notifications. With SNDBUF autotuning, this can result in a large amount of packets queued in qdisc/device on the local machine, hurting latency of other flows, for typical pfifo_fast qdiscs. tcp_limit_output_bytes limits the number of bytes on qdisc or device to reduce artificial RTT/cwnd and reduce bufferbloat. |
821b41440 net: Documentatio... |
702 |
Default: 262144 |
46d3ceabd tcp: TCP Small Qu... |
703 |
|
282f23c6e tcp: implement RF... |
704 705 706 707 |
tcp_challenge_ack_limit - INTEGER Limits number of Challenge ACK sent per second, as recommended in RFC 5961 (Improving TCP's Robustness to Blind In-Window Attacks) Default: 100 |
95766fff6 [UDP]: Add memory... |
708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 |
UDP variables: udp_mem - vector of 3 INTEGERs: min, pressure, max Number of pages allowed for queueing by all UDP sockets. min: Below this number of pages UDP is not bothered about its memory appetite. When amount of memory allocated by UDP exceeds this number, UDP starts to moderate memory usage. pressure: This value was introduced to follow format of tcp_mem. max: Number of pages allowed for queueing by all UDP sockets. Default is calculated at boot time from amount of available memory. udp_rmem_min - INTEGER Minimal size of receive buffer used by UDP sockets in moderation. Each UDP socket is able to use the size for receiving data, even if total pages of UDP sockets exceed udp_mem pressure. The unit is byte. |
6539fefd9 Update documented... |
727 |
Default: 1 page |
95766fff6 [UDP]: Add memory... |
728 729 730 731 732 |
udp_wmem_min - INTEGER Minimal size of send buffer used by UDP sockets in moderation. Each UDP socket is able to use the size for sending data, even if total pages of UDP sockets exceed udp_mem pressure. The unit is byte. |
6539fefd9 Update documented... |
733 |
Default: 1 page |
95766fff6 [UDP]: Add memory... |
734 |
|
8802f616f [NetLabel]: docum... |
735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 |
CIPSOv4 Variables: cipso_cache_enable - BOOLEAN 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". Default: 1 cipso_cache_bucket_size - INTEGER 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. Default: 10 cipso_rbm_optfmt - BOOLEAN 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. Default: 0 cipso_rbm_structvalid - BOOLEAN 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. Default: 0 |
1da177e4c Linux-2.6.12-rc2 |
769 770 771 772 |
IP Variables: ip_local_port_range - 2 INTEGERS Defines the local port range that is used by TCP and UDP to |
e18f5feb0 Doc: Cleanup whit... |
773 |
choose the local port. The first number is the first, the |
07f4c9006 tcp/dccp: try to ... |
774 775 776 777 |
second the last local port number. If possible, it is better these numbers have different parity. (one even and one odd values) The default values are 32768 and 60999 respectively. |
1da177e4c Linux-2.6.12-rc2 |
778 |
|
e3826f1e9 net: reserve port... |
779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 |
ip_local_reserved_ports - list of comma separated ranges Specify the ports which are reserved for known third-party applications. These ports will not be used by automatic port assignments (e.g. when calling connect() or bind() with port number 0). Explicit port allocation behavior is unchanged. The format used for both input and output is a comma separated list of ranges (e.g. "1,2-4,10-10" for ports 1, 2, 3, 4 and 10). Writing to the file will clear all previously reserved ports and update the current list with the one given in the input. Note that ip_local_port_range and ip_local_reserved_ports settings are independent and both are considered by the kernel when determining which ports are available for automatic port assignments. You can reserve ports which are not in the current ip_local_port_range, e.g.: $ cat /proc/sys/net/ipv4/ip_local_port_range |
07f4c9006 tcp/dccp: try to ... |
800 |
32000 60999 |
e3826f1e9 net: reserve port... |
801 802 803 804 805 806 807 808 |
$ cat /proc/sys/net/ipv4/ip_local_reserved_ports 8080,9148 although this is redundant. However such a setting is useful if later the port range is changed to a value that will include the reserved ports. Default: Empty |
1da177e4c Linux-2.6.12-rc2 |
809 810 811 812 813 814 815 816 817 818 819 |
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 |
e3d73bced net: add doc for ... |
820 821 822 823 824 825 826 827 |
ip_early_demux - BOOLEAN Optimize input packet processing down to one demux for certain kinds of local sockets. Currently we only do this for established TCP sockets. It may add an additional cost for pure routing workloads that reduces overall throughput, in such case you should disable it. Default: 1 |
1da177e4c Linux-2.6.12-rc2 |
828 |
icmp_echo_ignore_all - BOOLEAN |
7ce312467 [IPV4]: Update ic... |
829 830 831 |
If set non-zero, then the kernel will ignore all ICMP ECHO requests sent to it. Default: 0 |
1da177e4c Linux-2.6.12-rc2 |
832 |
icmp_echo_ignore_broadcasts - BOOLEAN |
7ce312467 [IPV4]: Update ic... |
833 834 835 |
If set non-zero, then the kernel will ignore all ICMP ECHO and TIMESTAMP requests sent to it via broadcast/multicast. Default: 1 |
1da177e4c Linux-2.6.12-rc2 |
836 837 838 839 |
icmp_ratelimit - INTEGER Limit the maximal rates for sending ICMP packets whose type matches icmp_ratemask (see below) to specific targets. |
6dbf4bcac icmp: fix units f... |
840 841 |
0 to disable any limiting, otherwise the minimal space between responses in milliseconds. |
4cdf507d5 icmp: add a globa... |
842 843 |
Note that another sysctl, icmp_msgs_per_sec limits the number of ICMP packets sent on all targets. |
6dbf4bcac icmp: fix units f... |
844 |
Default: 1000 |
1da177e4c Linux-2.6.12-rc2 |
845 |
|
4cdf507d5 icmp: add a globa... |
846 847 848 849 |
icmp_msgs_per_sec - INTEGER Limit maximal number of ICMP packets sent per second from this host. Only messages whose type matches icmp_ratemask (see below) are controlled by this limit. |
6dbf4bcac icmp: fix units f... |
850 |
Default: 1000 |
1da177e4c Linux-2.6.12-rc2 |
851 |
|
4cdf507d5 icmp: add a globa... |
852 853 854 855 |
icmp_msgs_burst - INTEGER icmp_msgs_per_sec controls number of ICMP packets sent per second, while icmp_msgs_burst controls the burst size of these packets. Default: 50 |
1da177e4c Linux-2.6.12-rc2 |
856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 |
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. |
e8b265e8b doc:networking: F... |
883 |
Default: 1 |
1da177e4c Linux-2.6.12-rc2 |
884 |
|
95f7daf1c [IPV4]: Document ... |
885 |
icmp_errors_use_inbound_ifaddr - BOOLEAN |
02a6d6136 Revert "ipv4/icmp... |
886 887 |
If zero, icmp error messages are sent with the primary address of the exiting interface. |
e18f5feb0 Doc: Cleanup whit... |
888 |
|
95f7daf1c [IPV4]: Document ... |
889 890 891 892 |
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 |
e18f5feb0 Doc: Cleanup whit... |
893 |
much easier. |
95f7daf1c [IPV4]: Document ... |
894 895 896 |
Note that if no primary address exists for the interface selected, then the primary address of the first non-loopback interface that |
d6bc8ac9e Fix typos in Docu... |
897 |
has one will be used regardless of this setting. |
95f7daf1c [IPV4]: Document ... |
898 899 |
Default: 0 |
1da177e4c Linux-2.6.12-rc2 |
900 901 902 |
igmp_max_memberships - INTEGER Change the maximum number of multicast groups we can subscribe to. Default: 20 |
d67ef35ff clarify documenta... |
903 904 905 906 |
Theoretical maximum value is bounded by having to send a membership report in a single datagram (i.e. the report can't span multiple datagrams, or risk confusing the switch and leaving groups you don't intend to). |
1da177e4c Linux-2.6.12-rc2 |
907 |
|
d67ef35ff clarify documenta... |
908 909 910 911 912 913 914 915 916 917 918 919 |
The number of supported groups 'M' is bounded by the number of group report entries you can fit into a single datagram of 65535 bytes. M = 65536-sizeof (ip header)/(sizeof(Group record)) Group records are variable length, with a minimum of 12 bytes. So net.ipv4.igmp_max_memberships should not be set higher than: (65536-24) / 12 = 5459 The value 5459 assumes no IP header options, so in practice this number may be lower. |
537377d3b igmp: Document sy... |
920 921 922 923 |
igmp_max_msf - INTEGER Maximum number of addresses allowed in the source filter list for a multicast group. Default: 10 |
a9fe8e299 ipv4: implement i... |
924 |
igmp_qrv - INTEGER |
537377d3b igmp: Document sy... |
925 926 927 |
Controls the IGMP query robustness variable (see RFC2236 8.1). Default: 2 (as specified by RFC2236 8.1) Minimum: 1 (as specified by RFC6636 4.5) |
a9fe8e299 ipv4: implement i... |
928 |
|
6b226e2f8 net: Fix indentat... |
929 930 931 932 |
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 |
1da177e4c Linux-2.6.12-rc2 |
933 934 935 936 937 938 939 940 941 |
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: |
e18f5feb0 Doc: Cleanup whit... |
942 943 |
- both conf/{all,interface}/accept_redirects are TRUE in the case forwarding for the interface is enabled |
1da177e4c Linux-2.6.12-rc2 |
944 |
or |
e18f5feb0 Doc: Cleanup whit... |
945 946 |
- at least one of conf/{all,interface}/accept_redirects is TRUE in the case forwarding for the interface is disabled |
1da177e4c Linux-2.6.12-rc2 |
947 948 949 950 951 952 953 954 955 956 |
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. |
e18f5feb0 Doc: Cleanup whit... |
957 958 |
conf/all/mc_forwarding must also be set to TRUE to enable multicast routing for the interface |
1da177e4c Linux-2.6.12-rc2 |
959 960 961 962 963 964 965 |
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. |
e18f5feb0 Doc: Cleanup whit... |
966 |
|
1da177e4c Linux-2.6.12-rc2 |
967 968 969 970 971 972 973 974 975 |
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 |
65324144b net: RFC3069, pri... |
976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 |
proxy_arp_pvlan - BOOLEAN Private VLAN proxy arp. Basically allow proxy arp replies back to the same interface (from which the ARP request/solicitation was received). This is done to support (ethernet) switch features, like RFC 3069, where the individual ports are NOT allowed to communicate with each other, but they are allowed to talk to the upstream router. As described in RFC 3069, it is possible to allow these hosts to communicate through the upstream router by proxy_arp'ing. Don't need to be used together with proxy_arp. This technology is known by different names: In RFC 3069 it is called VLAN Aggregation. Cisco and Allied Telesyn call it Private VLAN. Hewlett-Packard call it Source-Port filtering or port-isolation. Ericsson call it MAC-Forced Forwarding (RFC Draft). |
1da177e4c Linux-2.6.12-rc2 |
994 995 |
shared_media - BOOLEAN Send(router) or accept(host) RFC1620 shared media redirects. |
176b346b3 Documentation: ip... |
996 |
Overrides secure_redirects. |
1da177e4c Linux-2.6.12-rc2 |
997 998 999 1000 1001 1002 |
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 |
176b346b3 Documentation: ip... |
1003 1004 1005 1006 |
Accept ICMP redirect messages only to gateways listed in the interface's current gateway list. Even if disabled, RFC1122 redirect rules still apply. Overridden by shared_media. |
1da177e4c Linux-2.6.12-rc2 |
1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 |
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) |
8153a10c0 ipv4 05/05: add s... |
1034 |
accept_local - BOOLEAN |
72b126a45 Revert "ipv4: Cla... |
1035 1036 1037 |
Accept packets with local source addresses. In combination with suitable routing, this can be used to direct packets between two local interfaces over the wire and have them accepted properly. |
8153a10c0 ipv4 05/05: add s... |
1038 |
default FALSE |
d0daebc3d ipv4: Add interfa... |
1039 1040 1041 1042 |
route_localnet - BOOLEAN Do not consider loopback addresses as martian source or destination while routing. This enables the use of 127/8 for local routing purposes. default FALSE |
c1cf8422f ip: add loose rev... |
1043 |
rp_filter - INTEGER |
1da177e4c Linux-2.6.12-rc2 |
1044 |
0 - No source validation. |
c1cf8422f ip: add loose rev... |
1045 1046 1047 1048 1049 1050 1051 1052 |
1 - Strict mode as defined in RFC3704 Strict Reverse Path Each incoming packet is tested against the FIB and if the interface is not the best reverse path the packet check will fail. By default failed packets are discarded. 2 - Loose mode as defined in RFC3704 Loose Reverse Path Each incoming packet's source address is also tested against the FIB and if the source address is not reachable via any interface the packet check will fail. |
e18f5feb0 Doc: Cleanup whit... |
1053 |
Current recommended practice in RFC3704 is to enable strict mode |
bf869c306 Doc: Fix typos in... |
1054 |
to prevent IP spoofing from DDos attacks. If using asymmetric routing |
e18f5feb0 Doc: Cleanup whit... |
1055 |
or other complicated routing, then loose mode is recommended. |
c1cf8422f ip: add loose rev... |
1056 |
|
1f5865e73 ip: update the de... |
1057 1058 |
The max value from conf/{all,interface}/rp_filter is used when doing source validation on the {interface}. |
1da177e4c Linux-2.6.12-rc2 |
1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 |
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} |
eefef1cf7 net: add ARP noti... |
1130 1131 1132 |
arp_notify - BOOLEAN Define mode for notification of address and device changes. 0 - (default): do nothing |
3f8dc2362 arp_notify: docum... |
1133 |
1 - Generate gratuitous arp requests when device is brought up |
eefef1cf7 net: add ARP noti... |
1134 |
or hardware address changes. |
c1b1bce85 [IPV4] ARP: Docum... |
1135 |
arp_accept - BOOLEAN |
6d955180b ipv4: allow warmi... |
1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 |
Define behavior for gratuitous ARP frames who's IP is not already present in the ARP table: 0 - don't create new entries in the ARP table 1 - create new entries in the ARP table Both replies and requests type gratuitous arp will trigger the ARP table to be updated, if this setting is on. If the ARP table already contains the IP address of the gratuitous arp frame, the arp table will be updated regardless if this setting is on or off. |
89c69d3ce net: neighbour: D... |
1147 1148 1149 1150 1151 1152 1153 1154 |
mcast_solicit - INTEGER The maximum number of multicast probes in INCOMPLETE state, when the associated hardware address is unknown. Defaults to 3. ucast_solicit - INTEGER The maximum number of unicast probes in PROBE state, when the hardware address is being reconfirmed. Defaults to 3. |
c1b1bce85 [IPV4] ARP: Docum... |
1155 |
|
1da177e4c Linux-2.6.12-rc2 |
1156 1157 1158 |
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 |
89c69d3ce net: neighbour: D... |
1159 1160 1161 1162 1163 |
mcast_resolicit). Defaults to 0. mcast_resolicit - INTEGER The maximum number of multicast probes after unicast and app probes in PROBE state. Defaults to 0. |
1da177e4c Linux-2.6.12-rc2 |
1164 1165 1166 1167 1168 1169 |
disable_policy - BOOLEAN Disable IPSEC policy (SPD) for this interface disable_xfrm - BOOLEAN Disable IPSEC encryption on this interface, whatever the policy |
fc4eba58b ipv6: make unsoli... |
1170 1171 1172 1173 |
igmpv2_unsolicited_report_interval - INTEGER The interval in milliseconds in which the next unsolicited IGMPv1 or IGMPv2 report retransmit will take place. Default: 10000 (10 seconds) |
1da177e4c Linux-2.6.12-rc2 |
1174 |
|
fc4eba58b ipv6: make unsoli... |
1175 1176 1177 1178 |
igmpv3_unsolicited_report_interval - INTEGER The interval in milliseconds in which the next unsolicited IGMPv3 report retransmit will take place. Default: 1000 (1 seconds) |
1da177e4c Linux-2.6.12-rc2 |
1179 |
|
d922e1cb1 net: Document pro... |
1180 1181 1182 1183 |
promote_secondaries - BOOLEAN When a primary IP address is removed from this interface promote a corresponding secondary IP address instead of removing all the corresponding secondary IP addresses. |
12b74dfad ipv4: add option ... |
1184 1185 1186 1187 1188 1189 |
drop_unicast_in_l2_multicast - BOOLEAN Drop any unicast IP packets that are received in link-layer multicast (or broadcast) frames. This behavior (for multicast) is actually a SHOULD in RFC 1122, but is disabled by default for compatibility reasons. Default: off (0) |
97daf3314 ipv4: add option ... |
1190 1191 1192 1193 1194 |
drop_gratuitous_arp - BOOLEAN Drop all gratuitous ARP frames, for example if there's a known good ARP proxy on the network and such frames need not be used (or in the case of 802.11, must not be used to prevent attacks.) Default: off (0) |
d922e1cb1 net: Document pro... |
1195 |
|
1da177e4c Linux-2.6.12-rc2 |
1196 1197 1198 |
tag - INTEGER Allows you to write a number, which can be used as required. Default value is 0. |
e69948a0a net: Document xfr... |
1199 1200 1201 |
xfrm4_gc_thresh - INTEGER The threshold at which we will start garbage collecting for IPv4 destination cache entries. At twice this value the system will |
c386578f1 xfrm: Let the flo... |
1202 1203 |
refuse new allocations. The value must be set below the flowcache limit (4096 * number of online cpus) to take effect. |
e69948a0a net: Document xfr... |
1204 |
|
87583ebb9 IGMP: Document ig... |
1205 1206 1207 1208 |
igmp_link_local_mcast_reports - BOOLEAN Enable IGMP reports for link local multicast groups in the 224.0.0.X range. Default TRUE |
1da177e4c Linux-2.6.12-rc2 |
1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 |
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, |
e18f5feb0 Doc: Cleanup whit... |
1228 |
which restricts use of the IPv6 socket to IPv6 communication |
1da177e4c Linux-2.6.12-rc2 |
1229 1230 1231 |
only. TRUE: disable IPv4-mapped address feature FALSE: enable IPv4-mapped address feature |
d5c073caf net: Documentatio... |
1232 |
Default: FALSE (as specified in RFC3493) |
1da177e4c Linux-2.6.12-rc2 |
1233 |
|
6444f72b4 ipv6: add flowlab... |
1234 1235 1236 1237 1238 1239 1240 |
flowlabel_consistency - BOOLEAN Protect the consistency (and unicity) of flow label. You have to disable it to use IPV6_FL_F_REFLECT flag on the flow label manager. TRUE: enabled FALSE: disabled Default: TRUE |
42240901f ipv6: Implement d... |
1241 1242 1243 1244 |
auto_flowlabels - INTEGER Automatically generate flow labels based on a flow hash of the packet. This allows intermediate devices, such as routers, to identify packet flows for mechanisms like Equal Cost Multipath |
cb1ce2ef3 ipv6: Implement a... |
1245 |
Routing (see RFC 6438). |
42240901f ipv6: Implement d... |
1246 1247 1248 1249 1250 1251 1252 1253 |
0: automatic flow labels are completely disabled 1: automatic flow labels are enabled by default, they can be disabled on a per socket basis using the IPV6_AUTOFLOWLABEL socket option 2: automatic flow labels are allowed, they may be enabled on a per socket basis using the IPV6_AUTOFLOWLABEL socket option 3: automatic flow labels are enabled and enforced, they cannot be disabled by the socket option |
b56774163 ipv6: Enable auto... |
1254 |
Default: 1 |
cb1ce2ef3 ipv6: Implement a... |
1255 |
|
82a584b7c ipv6: Flow label ... |
1256 1257 1258 1259 1260 1261 1262 |
flowlabel_state_ranges - BOOLEAN Split the flow label number space into two ranges. 0-0x7FFFF is reserved for the IPv6 flow manager facility, 0x80000-0xFFFFF is reserved for stateless flow labels as described in RFC6437. TRUE: enabled FALSE: disabled Default: true |
509aba3b0 IPv6: add the opt... |
1263 1264 1265 1266 1267 1268 |
anycast_src_echo_reply - BOOLEAN Controls the use of anycast addresses as source addresses for ICMPv6 echo reply TRUE: enabled FALSE: disabled Default: FALSE |
9f0761c15 ipv6: add documen... |
1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 |
idgen_delay - INTEGER Controls the delay in seconds after which time to retry privacy stable address generation if a DAD conflict is detected. Default: 1 (as specified in RFC7217) idgen_retries - INTEGER Controls the number of retries to generate a stable privacy address if a DAD conflict is detected. Default: 3 (as specified in RFC7217) |
2f711939d ipv6: add sysctl_... |
1279 1280 1281 1282 |
mld_qrv - INTEGER Controls the MLD query robustness variable (see RFC3810 9.1). Default: 2 (as specified by RFC3810 9.1) Minimum: 1 (as specified by RFC6636 4.5) |
1da177e4c Linux-2.6.12-rc2 |
1283 1284 1285 |
IPv6 Fragmentation: ip6frag_high_thresh - INTEGER |
e18f5feb0 Doc: Cleanup whit... |
1286 |
Maximum memory used to reassemble IPv6 fragments. When |
1da177e4c Linux-2.6.12-rc2 |
1287 1288 1289 |
ip6frag_high_thresh bytes of memory is allocated for this purpose, the fragment handler will toss packets until ip6frag_low_thresh is reached. |
e18f5feb0 Doc: Cleanup whit... |
1290 |
|
1da177e4c Linux-2.6.12-rc2 |
1291 |
ip6frag_low_thresh - INTEGER |
e18f5feb0 Doc: Cleanup whit... |
1292 |
See ip6frag_high_thresh |
1da177e4c Linux-2.6.12-rc2 |
1293 1294 1295 |
ip6frag_time - INTEGER Time in seconds to keep an IPv6 fragment in memory. |
1da177e4c Linux-2.6.12-rc2 |
1296 1297 1298 1299 1300 |
conf/default/*: Change the interface-specific default settings. conf/all/*: |
e18f5feb0 Doc: Cleanup whit... |
1301 |
Change all the interface-specific settings. |
1da177e4c Linux-2.6.12-rc2 |
1302 1303 1304 1305 |
[XXX: Other special features than forwarding?] conf/all/forwarding - BOOLEAN |
e18f5feb0 Doc: Cleanup whit... |
1306 |
Enable global IPv6 forwarding between all interfaces. |
1da177e4c Linux-2.6.12-rc2 |
1307 |
|
e18f5feb0 Doc: Cleanup whit... |
1308 |
IPv4 and IPv6 work differently here; e.g. netfilter must be used |
1da177e4c Linux-2.6.12-rc2 |
1309 |
to control which interfaces may forward packets and which not. |
e18f5feb0 Doc: Cleanup whit... |
1310 |
This also sets all interfaces' Host/Router setting |
1da177e4c Linux-2.6.12-rc2 |
1311 1312 1313 |
'forwarding' to the specified value. See below for details. This referred to as global forwarding. |
fbea49e1e [IPV6] NDISC: Add... |
1314 1315 |
proxy_ndp - BOOLEAN Do proxy ndp. |
219b5f29a net: Add missing ... |
1316 1317 1318 1319 1320 1321 |
fwmark_reflect - BOOLEAN Controls the fwmark of kernel-generated IPv6 reply packets that are not associated with a socket for example, TCP RSTs or ICMPv6 echo replies). If unset, these packets have a fwmark of zero. If set, they have the fwmark of the packet they are replying to. Default: 0 |
1da177e4c Linux-2.6.12-rc2 |
1322 1323 |
conf/interface/*: Change special settings per interface. |
e18f5feb0 Doc: Cleanup whit... |
1324 |
The functional behaviour for certain settings is different |
1da177e4c Linux-2.6.12-rc2 |
1325 |
depending on whether local forwarding is enabled or not. |
605b91c8f net: Documentatio... |
1326 |
accept_ra - INTEGER |
1da177e4c Linux-2.6.12-rc2 |
1327 |
Accept Router Advertisements; autoconfigure using them. |
e18f5feb0 Doc: Cleanup whit... |
1328 |
|
026359bc6 ipv6: Send ICMPv6... |
1329 1330 1331 1332 |
It also determines whether or not to transmit Router Solicitations. If and only if the functional setting is to accept Router Advertisements, Router Solicitations will be transmitted. |
ae8abfa00 ipv6: Update ip-s... |
1333 1334 1335 1336 1337 |
Possible values are: 0 Do not accept Router Advertisements. 1 Accept Router Advertisements if forwarding is disabled. 2 Overrule forwarding behaviour. Accept Router Advertisements even if forwarding is enabled. |
1da177e4c Linux-2.6.12-rc2 |
1338 1339 |
Functional default: enabled if local forwarding is disabled. disabled if local forwarding is enabled. |
65f5c7c11 [IPV6]: ROUTE: Ad... |
1340 1341 1342 1343 1344 |
accept_ra_defrtr - BOOLEAN Learn default router in Router Advertisement. Functional default: enabled if accept_ra is enabled. disabled if accept_ra is disabled. |
d93331965 ipv6: Allow accep... |
1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 |
accept_ra_from_local - BOOLEAN Accept RA with source-address that is found on local machine if the RA is otherwise proper and able to be accepted. Default is to NOT accept these as it may be an un-intended network loop. Functional default: enabled if accept_ra_from_local is enabled on a specific interface. disabled if accept_ra_from_local is disabled on a specific interface. |
8013d1d7e net/ipv6: add sys... |
1356 1357 1358 1359 1360 1361 1362 |
accept_ra_min_hop_limit - INTEGER Minimum hop limit Information in Router Advertisement. Hop limit Information in Router Advertisement less than this variable shall be ignored. Default: 1 |
c4fd30eb1 [IPV6]: ADDRCONF:... |
1363 |
accept_ra_pinfo - BOOLEAN |
2fe0ae78c Fix typos in Docu... |
1364 |
Learn Prefix Information in Router Advertisement. |
c4fd30eb1 [IPV6]: ADDRCONF:... |
1365 1366 1367 |
Functional default: enabled if accept_ra is enabled. disabled if accept_ra is disabled. |
09c884d4c [IPV6]: ROUTE: Ad... |
1368 1369 1370 1371 1372 1373 1374 1375 |
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. |
930d6ff2e [IPV6]: ROUTE: Ad... |
1376 1377 1378 1379 1380 |
accept_ra_rtr_pref - BOOLEAN Accept Router Preference in RA. Functional default: enabled if accept_ra is enabled. disabled if accept_ra is disabled. |
c2943f145 net: ipv6: Add sy... |
1381 1382 1383 1384 1385 1386 |
accept_ra_mtu - BOOLEAN Apply the MTU value specified in RA option 5 (RFC4861). If disabled, the MTU specified in the RA will be ignored. Functional default: enabled if accept_ra is enabled. disabled if accept_ra is disabled. |
1da177e4c Linux-2.6.12-rc2 |
1387 1388 1389 1390 1391 |
accept_redirects - BOOLEAN Accept Redirects. Functional default: enabled if local forwarding is disabled. disabled if local forwarding is enabled. |
0bcbc9262 [IPV6]: Disallow ... |
1392 1393 |
accept_source_route - INTEGER Accept source routing (routing extension header). |
bb4dbf9e6 [IPV6]: Do not se... |
1394 |
>= 0: Accept only routing header type 2. |
0bcbc9262 [IPV6]: Disallow ... |
1395 1396 1397 |
< 0: Do not accept routing header. Default: 0 |
1da177e4c Linux-2.6.12-rc2 |
1398 |
autoconf - BOOLEAN |
e18f5feb0 Doc: Cleanup whit... |
1399 |
Autoconfigure addresses using Prefix Information in Router |
1da177e4c Linux-2.6.12-rc2 |
1400 |
Advertisements. |
c4fd30eb1 [IPV6]: ADDRCONF:... |
1401 1402 |
Functional default: enabled if accept_ra_pinfo is enabled. disabled if accept_ra_pinfo is disabled. |
1da177e4c Linux-2.6.12-rc2 |
1403 1404 1405 1406 |
dad_transmits - INTEGER The amount of Duplicate Address Detection probes to send. Default: 1 |
e18f5feb0 Doc: Cleanup whit... |
1407 |
|
605b91c8f net: Documentatio... |
1408 |
forwarding - INTEGER |
e18f5feb0 Doc: Cleanup whit... |
1409 |
Configure interface-specific Host/Router behaviour. |
1da177e4c Linux-2.6.12-rc2 |
1410 |
|
e18f5feb0 Doc: Cleanup whit... |
1411 |
Note: It is recommended to have the same setting on all |
1da177e4c Linux-2.6.12-rc2 |
1412 |
interfaces; mixed router/host scenarios are rather uncommon. |
ae8abfa00 ipv6: Update ip-s... |
1413 1414 1415 |
Possible values are: 0 Forwarding disabled 1 Forwarding enabled |
ae8abfa00 ipv6: Update ip-s... |
1416 1417 |
FALSE (0): |
1da177e4c Linux-2.6.12-rc2 |
1418 1419 1420 1421 |
By default, Host behaviour is assumed. This means: 1. IsRouter flag is not set in Neighbour Advertisements. |
026359bc6 ipv6: Send ICMPv6... |
1422 1423 |
2. If accept_ra is TRUE (default), transmit Router Solicitations. |
e18f5feb0 Doc: Cleanup whit... |
1424 |
3. If accept_ra is TRUE (default), accept Router |
1da177e4c Linux-2.6.12-rc2 |
1425 1426 |
Advertisements (and do autoconfiguration). 4. If accept_redirects is TRUE (default), accept Redirects. |
ae8abfa00 ipv6: Update ip-s... |
1427 |
TRUE (1): |
1da177e4c Linux-2.6.12-rc2 |
1428 |
|
e18f5feb0 Doc: Cleanup whit... |
1429 |
If local forwarding is enabled, Router behaviour is assumed. |
1da177e4c Linux-2.6.12-rc2 |
1430 1431 1432 |
This means exactly the reverse from the above: 1. IsRouter flag is set in Neighbour Advertisements. |
026359bc6 ipv6: Send ICMPv6... |
1433 |
2. Router Solicitations are not sent unless accept_ra is 2. |
ae8abfa00 ipv6: Update ip-s... |
1434 |
3. Router Advertisements are ignored unless accept_ra is 2. |
1da177e4c Linux-2.6.12-rc2 |
1435 |
4. Redirects are ignored. |
ae8abfa00 ipv6: Update ip-s... |
1436 1437 |
Default: 0 (disabled) if global forwarding is disabled (default), otherwise 1 (enabled). |
1da177e4c Linux-2.6.12-rc2 |
1438 1439 1440 1441 1442 1443 1444 1445 |
hop_limit - INTEGER Default Hop Limit to set. Default: 64 mtu - INTEGER Default Maximum Transfer Unit Default: 1280 (IPv6 required minimum) |
35a256fee ipv6: Nonlocal bind |
1446 1447 1448 1449 |
ip_nonlocal_bind - BOOLEAN If set, allows processes to bind() to non-local IPv6 addresses, which can be quite useful - but may break some applications. Default: 0 |
52e163563 [IPV6]: ROUTE: Ad... |
1450 1451 1452 1453 1454 |
router_probe_interval - INTEGER Minimum interval (in seconds) between Router Probing described in RFC4191. Default: 60 |
1da177e4c Linux-2.6.12-rc2 |
1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 |
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 |
e18f5feb0 Doc: Cleanup whit... |
1465 |
Number of Router Solicitations to send until assuming no |
1da177e4c Linux-2.6.12-rc2 |
1466 1467 |
routers are present. Default: 3 |
3985e8a36 ipv6: sysctl to r... |
1468 1469 1470 1471 1472 1473 |
use_oif_addrs_only - BOOLEAN When enabled, the candidate source addresses for destinations routed via this interface are restricted to the set of addresses configured on this interface (vis. RFC 6724, section 4). Default: false |
1da177e4c Linux-2.6.12-rc2 |
1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 |
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) |
f1705ec19 net: ipv6: Make a... |
1491 1492 1493 1494 1495 1496 1497 1498 |
keep_addr_on_down - INTEGER Keep all IPv6 addresses on an interface down event. If set static global addresses with no expiration time are not flushed. >0 : enabled 0 : system default <0 : disabled Default: 0 (addresses are removed) |
1da177e4c Linux-2.6.12-rc2 |
1499 1500 |
max_desync_factor - INTEGER Maximum value for DESYNC_FACTOR, which is a random value |
e18f5feb0 Doc: Cleanup whit... |
1501 |
that ensures that clients don't synchronize with each |
1da177e4c Linux-2.6.12-rc2 |
1502 1503 1504 |
other and generate new addresses at exactly the same time. value is in seconds. Default: 600 |
e18f5feb0 Doc: Cleanup whit... |
1505 |
|
1da177e4c Linux-2.6.12-rc2 |
1506 1507 1508 1509 1510 1511 |
regen_max_retry - INTEGER Number of attempts before give up attempting to generate valid temporary addresses. Default: 5 max_addresses - INTEGER |
e79dc4843 IPv6: better docu... |
1512 1513 1514 1515 |
Maximum number of autoconfigured addresses per interface. Setting to zero disables the limitation. It is not recommended to set this value too large (or to zero) because it would be an easy way to crash the kernel by allowing too many addresses to be created. |
1da177e4c Linux-2.6.12-rc2 |
1516 |
Default: 16 |
778d80be5 ipv6: Add disable... |
1517 |
disable_ipv6 - BOOLEAN |
9bdd8d40c ipv6: Fix incorre... |
1518 1519 1520 |
Disable IPv6 operation. If accept_dad is set to 2, this value will be dynamically set to TRUE if DAD fails for the link-local address. |
778d80be5 ipv6: Add disable... |
1521 |
Default: FALSE (enable IPv6 operation) |
56d417b12 IPv6: Add 'autoco... |
1522 1523 1524 1525 1526 1527 |
When this value is changed from 1 to 0 (IPv6 is being enabled), it will dynamically create a link-local address on the given interface and start Duplicate Address Detection, if necessary. When this value is changed from 0 to 1 (IPv6 is being disabled), it will dynamically delete all address on the given interface. |
1b34be74c ipv6 addrconf: ad... |
1528 1529 1530 1531 1532 1533 |
accept_dad - INTEGER Whether to accept DAD (Duplicate Address Detection). 0: Disable DAD 1: Enable DAD (default) 2: Enable DAD, and disable IPv6 operation if MAC-based duplicate link-local address has been found. |
f7734fdf6 make TLLAO option... |
1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 |
force_tllao - BOOLEAN Enable sending the target link-layer address option even when responding to a unicast neighbor solicitation. Default: FALSE Quoting from RFC 2461, section 4.4, Target link-layer address: "The option MUST be included for multicast solicitations in order to avoid infinite Neighbor Solicitation "recursion" when the peer node does not have a cache entry to return a Neighbor Advertisements message. When responding to unicast solicitations, the option can be omitted since the sender of the solicitation has the correct link- layer address; otherwise it would not have be able to send the unicast solicitation in the first place. However, including the link-layer address in this case adds little overhead and eliminates a potential race condition where the sender deletes the cached link-layer address prior to receiving a response to a previous solicitation." |
db2b620aa ipv6: document nd... |
1551 1552 1553 1554 1555 |
ndisc_notify - BOOLEAN Define mode for notification of address and device changes. 0 - (default): do nothing 1 - Generate unsolicited neighbour advertisements when device is brought up or hardware address changes. |
fc4eba58b ipv6: make unsoli... |
1556 1557 1558 1559 1560 1561 1562 1563 1564 |
mldv1_unsolicited_report_interval - INTEGER The interval in milliseconds in which the next unsolicited MLDv1 report retransmit will take place. Default: 10000 (10 seconds) mldv2_unsolicited_report_interval - INTEGER The interval in milliseconds in which the next unsolicited MLDv2 report retransmit will take place. Default: 1000 (1 second) |
f21278108 net: ipv6: mld: d... |
1565 1566 1567 1568 |
force_mld_version - INTEGER 0 - (default) No enforcement of a MLD version, MLDv1 fallback allowed 1 - Enforce to use MLD version 1 2 - Enforce to use MLD version 2 |
b800c3b96 ipv6: drop fragme... |
1569 1570 1571 1572 1573 |
suppress_frag_ndisc - INTEGER Control RFC 6980 (Security Implications of IPv6 Fragmentation with IPv6 Neighbor Discovery) behavior: 1 - (default) discard fragmented neighbor discovery packets 0 - allow fragmented neighbor discovery packets |
7fd2561e4 net: ipv6: Add a ... |
1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 |
optimistic_dad - BOOLEAN Whether to perform Optimistic Duplicate Address Detection (RFC 4429). 0: disabled (default) 1: enabled use_optimistic - BOOLEAN If enabled, do not classify optimistic addresses as deprecated during source address selection. Preferred addresses will still be chosen before optimistic addresses, subject to other ranking in the source address selection algorithm. 0: disabled (default) 1: enabled |
9f0761c15 ipv6: add documen... |
1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 |
stable_secret - IPv6 address This IPv6 address will be used as a secret to generate IPv6 addresses for link-local addresses and autoconfigured ones. All addresses generated after setting this secret will be stable privacy ones by default. This can be changed via the addrgenmode ip-link. conf/default/stable_secret is used as the secret for the namespace, the interface specific ones can overwrite that. Writes to conf/all/stable_secret are refused. It is recommended to generate this secret during installation of a system and keep it stable after that. By default the stable secret is unset. |
abbc30436 ipv6: add option ... |
1599 1600 1601 1602 1603 |
drop_unicast_in_l2_multicast - BOOLEAN Drop any unicast IPv6 packets that are received in link-layer multicast (or broadcast) frames. By default this is turned off. |
7a02bf892 ipv6: add option ... |
1604 1605 1606 1607 1608 1609 |
drop_unsolicited_na - BOOLEAN Drop all unsolicited neighbor advertisements, for example if there's a known good NA proxy on the network and such frames need not be used (or in the case of 802.11, must not be used to prevent attacks.) By default this is turned off. |
1da177e4c Linux-2.6.12-rc2 |
1610 1611 1612 |
icmp/*: ratelimit - INTEGER Limit the maximal rates for sending ICMPv6 packets. |
6dbf4bcac icmp: fix units f... |
1613 1614 1615 |
0 to disable any limiting, otherwise the minimal space between responses in milliseconds. Default: 1000 |
1da177e4c Linux-2.6.12-rc2 |
1616 |
|
e69948a0a net: Document xfr... |
1617 1618 1619 |
xfrm6_gc_thresh - INTEGER The threshold at which we will start garbage collecting for IPv6 destination cache entries. At twice this value the system will |
c386578f1 xfrm: Let the flo... |
1620 1621 |
refuse new allocations. The value must be set below the flowcache limit (4096 * number of online cpus) to take effect. |
e69948a0a net: Document xfr... |
1622 |
|
1da177e4c Linux-2.6.12-rc2 |
1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 |
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 |
516299d2f [NETFILTER]: brid... |
1647 1648 |
1 : pass bridged vlan-tagged ARP/IP/IPv6 traffic to {arp,ip,ip6}tables. 0 : disable this. |
4981682cc netfilter: bridge... |
1649 |
Default: 0 |
516299d2f [NETFILTER]: brid... |
1650 1651 1652 |
bridge-nf-filter-pppoe-tagged - BOOLEAN 1 : pass bridged pppoe-tagged IP/IPv6 traffic to {ip,ip6}tables. |
1da177e4c Linux-2.6.12-rc2 |
1653 |
0 : disable this. |
4981682cc netfilter: bridge... |
1654 |
Default: 0 |
1da177e4c Linux-2.6.12-rc2 |
1655 |
|
4981682cc netfilter: bridge... |
1656 1657 1658 1659 1660 1661 1662 1663 1664 |
bridge-nf-pass-vlan-input-dev - BOOLEAN 1: if bridge-nf-filter-vlan-tagged is enabled, try to find a vlan interface on the bridge and set the netfilter input device to the vlan. This allows use of e.g. "iptables -i br0.1" and makes the REDIRECT target work with vlan-on-top-of-bridge interfaces. When no matching vlan interface is found, or this switch is off, the input device is set to the bridge interface. 0: disable bridge netfilter vlan interface lookup. Default: 0 |
1da177e4c Linux-2.6.12-rc2 |
1665 |
|
32e8d4948 sctp: Add documen... |
1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 |
proc/sys/net/sctp/* Variables: addip_enable - BOOLEAN Enable or disable extension of Dynamic Address Reconfiguration (ADD-IP) functionality specified in RFC5061. This extension provides the ability to dynamically add and remove new addresses for the SCTP associations. 1: Enable extension. 0: Disable extension. Default: 0 |
566178f85 net: sctp: dynami... |
1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 |
pf_enable - INTEGER Enable or disable pf (pf is short for potentially failed) state. A value of pf_retrans > path_max_retrans also disables pf state. That is, one of both pf_enable and pf_retrans > path_max_retrans can disable pf state. Since pf_retrans and path_max_retrans can be changed by userspace application, sometimes user expects to disable pf state by the value of pf_retrans > path_max_retrans, but occasionally the value of pf_retrans or path_max_retrans is changed by the user application, this pf state is enabled. As such, it is necessary to add this to dynamically enable and disable pf state. See: https://datatracker.ietf.org/doc/draft-ietf-tsvwg-sctp-failover for details. 1: Enable pf. 0: Disable pf. Default: 1 |
32e8d4948 sctp: Add documen... |
1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 |
addip_noauth_enable - BOOLEAN Dynamic Address Reconfiguration (ADD-IP) requires the use of authentication to protect the operations of adding or removing new addresses. This requirement is mandated so that unauthorized hosts would not be able to hijack associations. However, older implementations may not have implemented this requirement while allowing the ADD-IP extension. For reasons of interoperability, we provide this variable to control the enforcement of the authentication requirement. 1: Allow ADD-IP extension to be used without authentication. This should only be set in a closed environment for interoperability with older implementations. 0: Enforce the authentication requirement Default: 0 auth_enable - BOOLEAN Enable or disable Authenticated Chunks extension. This extension provides the ability to send and receive authenticated chunks and is required for secure operation of Dynamic Address Reconfiguration (ADD-IP) extension. 1: Enable this extension. 0: Disable this extension. Default: 0 prsctp_enable - BOOLEAN Enable or disable the Partial Reliability extension (RFC3758) which is used to notify peers that a given DATA should no longer be expected. 1: Enable extension 0: Disable Default: 1 max_burst - INTEGER The limit of the number of new packets that can be initially sent. It controls how bursty the generated traffic can be. Default: 4 association_max_retrans - INTEGER Set the maximum number for retransmissions that an association can attempt deciding that the remote end is unreachable. If this value is exceeded, the association is terminated. Default: 10 max_init_retransmits - INTEGER The maximum number of retransmissions of INIT and COOKIE-ECHO chunks that an association will attempt before declaring the destination unreachable and terminating. Default: 8 path_max_retrans - INTEGER The maximum number of retransmissions that will be attempted on a given path. Once this threshold is exceeded, the path is considered unreachable, and new traffic will use a different path when the association is multihomed. Default: 5 |
5aa93bcf6 sctp: Implement q... |
1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 |
pf_retrans - INTEGER The number of retransmissions that will be attempted on a given path before traffic is redirected to an alternate transport (should one exist). Note this is distinct from path_max_retrans, as a path that passes the pf_retrans threshold can still be used. Its only deprioritized when a transmission path is selected by the stack. This setting is primarily used to enable fast failover mechanisms without having to reduce path_max_retrans to a very low value. See: http://www.ietf.org/id/draft-nishida-tsvwg-sctp-failover-05.txt for details. Note also that a value of pf_retrans > path_max_retrans |
566178f85 net: sctp: dynami... |
1772 1773 1774 |
disables this feature. Since both pf_retrans and path_max_retrans can be changed by userspace application, a variable pf_enable is used to disable pf state. |
5aa93bcf6 sctp: Implement q... |
1775 1776 |
Default: 0 |
32e8d4948 sctp: Add documen... |
1777 1778 1779 1780 1781 1782 |
rto_initial - INTEGER The initial round trip timeout value in milliseconds that will be used in calculating round trip times. This is the initial time interval for retransmissions. Default: 3000 |
1da177e4c Linux-2.6.12-rc2 |
1783 |
|
32e8d4948 sctp: Add documen... |
1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 |
rto_max - INTEGER The maximum value (in milliseconds) of the round trip timeout. This is the largest time interval that can elapse between retransmissions. Default: 60000 rto_min - INTEGER The minimum value (in milliseconds) of the round trip timeout. This is the smallest time interval the can elapse between retransmissions. Default: 1000 hb_interval - INTEGER The interval (in milliseconds) between HEARTBEAT chunks. These chunks are sent at the specified interval on idle paths to probe the state of a given path between 2 associations. Default: 30000 sack_timeout - INTEGER The amount of time (in milliseconds) that the implementation will wait to send a SACK. Default: 200 valid_cookie_life - INTEGER The default lifetime of the SCTP cookie (in milliseconds). The cookie is used during association establishment. Default: 60000 cookie_preserve_enable - BOOLEAN Enable or disable the ability to extend the lifetime of the SCTP cookie that is used during the establishment phase of SCTP association 1: Enable cookie lifetime extension. 0: Disable Default: 1 |
3c68198e7 sctp: Make hmac a... |
1823 1824 1825 1826 1827 1828 1829 1830 |
cookie_hmac_alg - STRING Select the hmac algorithm used when generating the cookie value sent by a listening sctp socket to a connecting client in the INIT-ACK chunk. Valid values are: * md5 * sha1 * none Ability to assign md5 or sha1 as the selected alg is predicated on the |
3b09adcb2 ip-sysctl: fix sp... |
1831 |
configuration of those algorithms at build time (CONFIG_CRYPTO_MD5 and |
3c68198e7 sctp: Make hmac a... |
1832 1833 1834 1835 |
CONFIG_CRYPTO_SHA1). Default: Dependent on configuration. MD5 if available, else SHA1 if available, else none. |
32e8d4948 sctp: Add documen... |
1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 |
rcvbuf_policy - INTEGER Determines if the receive buffer is attributed to the socket or to association. SCTP supports the capability to create multiple associations on a single socket. When using this capability, it is possible that a single stalled association that's buffering a lot of data may block other associations from delivering their data by consuming all of the receive buffer space. To work around this, the rcvbuf_policy could be set to attribute the receiver buffer space to each association instead of the socket. This prevents the described blocking. 1: rcvbuf space is per association |
3b09adcb2 ip-sysctl: fix sp... |
1848 |
0: rcvbuf space is per socket |
32e8d4948 sctp: Add documen... |
1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 |
Default: 0 sndbuf_policy - INTEGER Similar to rcvbuf_policy above, this applies to send buffer space. 1: Send buffer is tracked per association 0: Send buffer is tracked per socket. Default: 0 sctp_mem - vector of 3 INTEGERs: min, pressure, max Number of pages allowed for queueing by all SCTP sockets. min: Below this number of pages SCTP is not bothered about its memory appetite. When amount of memory allocated by SCTP exceeds this number, SCTP starts to moderate memory usage. pressure: This value was introduced to follow format of tcp_mem. max: Number of pages allowed for queueing by all SCTP sockets. Default is calculated at boot time from amount of available memory. sctp_rmem - vector of 3 INTEGERs: min, default, max |
a6e1204b8 Update descriptio... |
1874 1875 1876 1877 1878 1879 1880 1881 |
Only the first value ("min") is used, "default" and "max" are ignored. min: Minimal size of receive buffer used by SCTP socket. It is guaranteed to each SCTP socket (but not association) even under moderate memory pressure. Default: 1 page |
32e8d4948 sctp: Add documen... |
1882 1883 |
sctp_wmem - vector of 3 INTEGERs: min, default, max |
a6e1204b8 Update descriptio... |
1884 |
Currently this tunable has no effect. |
32e8d4948 sctp: Add documen... |
1885 |
|
723884339 sctp: Sysctl conf... |
1886 1887 1888 1889 1890 1891 1892 1893 1894 |
addr_scope_policy - INTEGER Control IPv4 address scoping - draft-stewart-tsvwg-sctp-ipv4-00 0 - Disable IPv4 address scoping 1 - Enable IPv4 address scoping 2 - Follow draft but allow IPv4 private addresses 3 - Follow draft but allow IPv4 link local addresses Default: 1 |
1da177e4c Linux-2.6.12-rc2 |
1895 |
|
4edc2f341 ip: sysctl docume... |
1896 |
/proc/sys/net/core/* |
c60f6aa8a net: doc: merge /... |
1897 |
Please see: Documentation/sysctl/net.txt for descriptions of these entries. |
705efc3b0 Doc: fixed descri... |
1898 |
|
4edc2f341 ip: sysctl docume... |
1899 1900 |
/proc/sys/net/unix/* |
705efc3b0 Doc: fixed descri... |
1901 1902 1903 1904 1905 1906 1907 |
max_dgram_qlen - INTEGER The maximum length of dgram socket receive queue Default: 10 UNDOCUMENTED: |
4edc2f341 ip: sysctl docume... |
1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 |
/proc/sys/net/irda/* fast_poll_increase FIXME warn_noreply_time FIXME discovery_slots FIXME slot_timeout FIXME max_baud_rate FIXME discovery_timeout FIXME lap_keepalive_time FIXME max_noreply_time FIXME max_tx_data_size FIXME max_tx_window FIXME min_tx_turn_time FIXME |