diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 2 | ||||
| -rw-r--r-- | Documentation/admin-guide/sysctl/net.rst | 2 | ||||
| -rw-r--r-- | Documentation/networking/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/networking/ip-sysctl.rst (renamed from Documentation/networking/ip-sysctl.txt) | 831 | ||||
| -rw-r--r-- | Documentation/networking/snmp_counter.rst | 2 | ||||
| -rw-r--r-- | net/Kconfig | 2 | ||||
| -rw-r--r-- | net/ipv4/Kconfig | 2 | ||||
| -rw-r--r-- | net/ipv4/icmp.c | 2 |
8 files changed, 560 insertions, 284 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index b23ab11587a6..e37db6f1be64 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4910,7 +4910,7 @@ Set the number of tcp_metrics_hash slots. Default value is 8192 or 16384 depending on total ram pages. This is used to specify the TCP metrics - cache size. See Documentation/networking/ip-sysctl.txt + cache size. See Documentation/networking/ip-sysctl.rst "tcp_no_metrics_save" section for more details. tdfx= [HW,DRM] diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst index e043c9213388..84e3348a9543 100644 --- a/Documentation/admin-guide/sysctl/net.rst +++ b/Documentation/admin-guide/sysctl/net.rst @@ -353,7 +353,7 @@ socket's buffer. It will not take effect unless PF_UNIX flag is specified. 3. /proc/sys/net/ipv4 - IPV4 settings ------------------------------------- -Please see: Documentation/networking/ip-sysctl.txt and ipvs-sysctl.txt for +Please see: Documentation/networking/ip-sysctl.rst and ipvs-sysctl.txt for descriptions of these entries. diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst index 3efb4608649a..7d133d8dbe2a 100644 --- a/Documentation/networking/index.rst +++ b/Documentation/networking/index.rst @@ -69,6 +69,7 @@ Contents: ip_dynaddr iphase ipsec + ip-sysctl .. only:: subproject and html diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.rst index 5cdc37c34830..38f811d4b2f0 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.rst @@ -1,8 +1,15 @@ -/proc/sys/net/ipv4/* Variables: +.. SPDX-License-Identifier: GPL-2.0 + +========= +IP Sysctl +========= + +/proc/sys/net/ipv4/* Variables +============================== ip_forward - BOOLEAN - 0 - disabled (default) - not 0 - enabled + - 0 - disabled (default) + - not 0 - enabled Forward Packets between interfaces. @@ -38,6 +45,7 @@ ip_no_pmtu_disc - INTEGER could break other protocols. Possible values: 0-3 + Default: FALSE min_pmtu - INTEGER @@ -51,16 +59,20 @@ ip_forward_use_pmtu - BOOLEAN 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 + + - 0 - disabled + - 1 - enabled 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 fib_multipath_use_neigh - BOOLEAN @@ -68,63 +80,80 @@ fib_multipath_use_neigh - BOOLEAN 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 + + - 0 - disabled + - 1 - enabled fib_multipath_hash_policy - INTEGER Controls which hash policy to use for multipath routes. Only valid for kernels built with CONFIG_IP_ROUTE_MULTIPATH enabled. + Default: 0 (Layer 3) + Possible values: - 0 - Layer 3 - 1 - Layer 4 - 2 - Layer 3 or inner Layer 3 if present + + - 0 - Layer 3 + - 1 - Layer 4 + - 2 - Layer 3 or inner Layer 3 if present fib_sync_mem - UNSIGNED INTEGER Amount of dirty memory from fib entries that can be backlogged before synchronize_rcu is forced. - Default: 512kB Minimum: 64kB Maximum: 64MB + + Default: 512kB Minimum: 64kB Maximum: 64MB ip_forward_update_priority - INTEGER Whether to update SKB priority from "TOS" field in IPv4 header after it is forwarded. The new SKB priority is mapped from TOS field value according to an rt_tos2priority table (see e.g. man tc-prio). + Default: 1 (Update priority.) + Possible values: - 0 - Do not update priority. - 1 - Update priority. + + - 0 - Do not update priority. + - 1 - Update priority. route/max_size - INTEGER Maximum number of routes allowed in the kernel. Increase this when using large numbers of interfaces and/or routes. + From linux kernel 3.6 onwards, this is deprecated for ipv4 as route cache is no longer used. neigh/default/gc_thresh1 - INTEGER Minimum number of entries to keep. Garbage collector will not purge entries if there are fewer than this number. + Default: 128 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 neigh/default/gc_thresh3 - INTEGER Maximum number of non-PERMANENT neighbor entries allowed. Increase this when using large numbers of interfaces and when communicating with large numbers of directly-connected peers. + Default: 1024 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) + Setting negative value is meaningless and will return error. + Default: SK_WMEM_MAX, (same as net.core.wmem_default). + Exact value depends on architecture and kernel options, but should be enough to allow queuing 256 packets of medium size. @@ -132,11 +161,14 @@ neigh/default/unres_qlen_bytes - INTEGER 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. + Prior to linux 3.3, the default value is 3 which may cause unexpected packet loss. The current default value is calculated according to default value of unres_qlen_bytes and true size of packet. + Default: 101 mtu_expires - INTEGER @@ -183,7 +215,8 @@ ipfrag_max_dist - INTEGER from different IP datagrams, which could result in data corruption. Default: 64 -INET peer storage: +INET peer storage +================= inet_peer_threshold - INTEGER The approximate size of the storage. Starting from this threshold @@ -203,7 +236,8 @@ inet_peer_maxttl - INTEGER when the number of entries in the pool is very small). Measured in seconds. -TCP variables: +TCP variables +============= somaxconn - INTEGER Limit of socket listen() backlog, known in userspace as SOMAXCONN. @@ -222,18 +256,22 @@ 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. + Possible values are [-31, 31], inclusive. + Default: 1 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). 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 tcp_autocorking - BOOLEAN @@ -244,6 +282,7 @@ tcp_autocorking - BOOLEAN 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 tcp_available_congestion_control - STRING @@ -265,6 +304,7 @@ tcp_mtu_probe_floor - INTEGER tcp_min_snd_mss - INTEGER TCP SYN and SYNACK messages usually advertise an ADVMSS option, as described in RFC 1122 and RFC 6691. + If this ADVMSS option is smaller than tcp_min_snd_mss, it is silently capped to tcp_min_snd_mss. @@ -277,6 +317,7 @@ tcp_congestion_control - STRING Default is set as part of kernel configuration. For passive connections, the listener congestion control choice is inherited. + [see setsockopt(listenfd, SOL_TCP, TCP_CONGESTION, "name" ...) ] tcp_dsack - BOOLEAN @@ -286,9 +327,12 @@ tcp_early_retrans - INTEGER Tail loss probe (TLP) converts RTOs occurring due to tail losses into fast recovery (draft-ietf-tcpm-rack). Note that TLP requires RACK to function properly (see tcp_recovery below) + Possible values: - 0 disables TLP - 3 or 4 enables TLP + + - 0 disables TLP + - 3 or 4 enables TLP + Default: 3 tcp_ecn - INTEGER @@ -297,12 +341,17 @@ tcp_ecn - INTEGER 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. + Possible values are: - 0 Disable ECN. Neither initiate nor accept ECN. - 1 Enable ECN when requested by incoming connections and - also request ECN on outgoing connection attempts. - 2 Enable ECN when requested by incoming connections - but do not request ECN on outgoing connections. + + = ===================================================== + 0 Disable ECN. Neither initiate nor accept ECN. + 1 Enable ECN when requested by incoming connections and + also request ECN on outgoing connection attempts. + 2 Enable ECN when requested by incoming connections + but do not request ECN on outgoing connections. + = ===================================================== + Default: 2 tcp_ecn_fallback - BOOLEAN @@ -312,6 +361,7 @@ tcp_ecn_fallback - BOOLEAN 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) tcp_fack - BOOLEAN @@ -324,7 +374,9 @@ tcp_fin_timeout - INTEGER 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 tcp_frto - INTEGER @@ -390,7 +442,8 @@ tcp_l3mdev_accept - BOOLEAN 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. - Default: 0 (disabled) + + Default: 0 (disabled) tcp_low_latency - BOOLEAN This is a legacy option, it has no effect anymore. @@ -410,10 +463,14 @@ tcp_max_orphans - INTEGER tcp_max_syn_backlog - INTEGER Maximal number of remembered connection requests (SYN_RECV), which have not received an acknowledgment from connecting client. + This is a per-listener limit. + 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. + Remember to also check /proc/sys/net/core/somaxconn A SYN_RECV request socket consumes about 304 bytes of memory. @@ -445,7 +502,9 @@ tcp_min_rtt_wlen - INTEGER 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. + Possible values: 0 - 86400 (1 day) + Default: 300 tcp_moderate_rcvbuf - BOOLEAN @@ -457,9 +516,10 @@ tcp_moderate_rcvbuf - BOOLEAN 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. + + - 0 - Disabled + - 1 - Disabled by default, enabled when an ICMP black hole detected + - 2 - Always enabled, use initial MSS of tcp_base_mss. tcp_probe_interval - UNSIGNED INTEGER Controls how often to start TCP Packetization-Layer Path MTU @@ -481,6 +541,7 @@ tcp_no_metrics_save - BOOLEAN tcp_no_ssthresh_metrics_save - BOOLEAN Controls whether TCP saves ssthresh metrics in the route cache. + Default is 1, which disables ssthresh metrics. tcp_orphan_retries - INTEGER @@ -489,6 +550,7 @@ tcp_orphan_retries - INTEGER See tcp_retries2 for more details. The default value is 8. + If your machine is a loaded WEB server, you should think about lowering this value, such sockets may consume significant resources. Cf. tcp_max_orphans. @@ -497,11 +559,15 @@ 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. It also subsumes and disables - RFC6675 recovery for SACK connections. - RACK: 0x2 makes RACK's reordering window static (min_rtt/4). - RACK: 0x4 disables RACK's DUPACK threshold heuristic + ========= ============================================================= + RACK: 0x1 enables the RACK loss detection for fast detection of lost + retransmissions and tail drops. It also subsumes and disables + RFC6675 recovery for SACK connections. + + RACK: 0x2 makes RACK's reordering window static (min_rtt/4). + + RACK: 0x4 disables RACK's DUPACK threshold heuristic + ========= ============================================================= Default: 0x1 @@ -509,12 +575,14 @@ tcp_reordering - INTEGER 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 + Default: 3 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 tcp_retrans_collapse - BOOLEAN @@ -550,12 +618,14 @@ 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 tcp_rmem - vector of 3 INTEGERs: min, default, max min: Minimal size of receive buffer used by TCP sockets. It is guaranteed to each TCP socket, even under moderate memory pressure. + Default: 4K default: initial size of receive buffer used by TCP sockets. @@ -592,12 +662,14 @@ tcp_slow_start_after_idle - BOOLEAN 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 tcp_stdurg - BOOLEAN Use the Host requirements interpretation of the TCP urgent pointer field. Most hosts use the older BSD interpretation, so if you turn this on Linux might not communicate correctly with them. + Default: FALSE tcp_synack_retries - INTEGER @@ -646,15 +718,18 @@ tcp_fastopen - INTEGER the option value being the length of the syn-data backlog. 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 + + ===== ======== ====================================================== + 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 + 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 + 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 @@ -668,6 +743,7 @@ tcp_fastopen_blackhole_timeout_sec - INTEGER get detected right after Fastopen is re-enabled and will reset to initial value when the blackhole issue goes away. 0 to disable the blackhole detection. + By default, it is set to 1hr. tcp_fastopen_key - list of comma separated 32-digit hexadecimal INTEGERs @@ -698,20 +774,24 @@ tcp_syn_retries - INTEGER for an active TCP connection attempt will happen after 127seconds. tcp_timestamps - INTEGER -Enable timestamps as defined in RFC1323. - 0: Disabled. - 1: Enable timestamps as defined in RFC1323 and use random offset for - each connection rather than only using the current time. - 2: Like 1, but without random offsets. + Enable timestamps as defined in RFC1323. + + - 0: Disabled. + - 1: Enable timestamps as defined in RFC1323 and use random offset for + each connection rather than only using the current time. + - 2: Like 1, but without random offsets. + Default: 1 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 tcp_pacing_ss_ratio - INTEGER @@ -720,6 +800,7 @@ tcp_pacing_ss_ratio - INTEGER 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 @@ -727,6 +808,7 @@ tcp_pacing_ca_ratio - INTEGER 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 tcp_tso_win_divisor - INTEGER @@ -734,16 +816,20 @@ tcp_tso_win_divisor - INTEGER 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 tcp_tw_reuse - INTEGER Enable reuse of TIME-WAIT sockets for new connections when it is safe from protocol viewpoint. - 0 - disable - 1 - global enable - 2 - enable for loopback traffic only + + - 0 - disable + - 1 - global enable + - 2 - enable for loopback traffic only + It should not be changed without advice/request of technical experts. + Default: 2 tcp_window_scaling - BOOLEAN @@ -752,11 +838,14 @@ tcp_window_scaling - BOOLEAN tcp_wmem - vector of 3 INTEGERs: min, default, max min: Amount of memory reserved for send buffers for TCP sockets. Each TCP socket has rights to use it due to fact of its birth. + Default: 4K 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. + Default: 16K max: Maximal amount of memory allowed for automatically tuned @@ -764,6 +853,7 @@ tcp_wmem - vector of 3 INTEGERs: min, default, max 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. tcp_notsent_lowat - UNSIGNED INTEGER @@ -784,6 +874,7 @@ tcp_workaround_signed_windows - BOOLEAN 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 tcp_thin_linear_timeouts - BOOLEAN @@ -796,6 +887,7 @@ tcp_thin_linear_timeouts - BOOLEAN non-aggressive thin streams, often found to be time-dependent. For more information on thin streams, see Documentation/networking/tcp-thin.txt + Default: 0 tcp_limit_output_bytes - INTEGER @@ -807,6 +899,7 @@ tcp_limit_output_bytes - INTEGER 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. + Default: 1048576 (16 * 65536) tcp_challenge_ack_limit - INTEGER @@ -822,7 +915,8 @@ tcp_rx_skb_cache - BOOLEAN Default: 0 (disabled) -UDP variables: +UDP variables +============= udp_l3mdev_accept - BOOLEAN Enabling this option allows a "global" bound socket to work @@ -830,7 +924,8 @@ udp_l3mdev_accept - BOOLEAN being received regardless of the L3 domain in which they originated. Only valid when the kernel was compiled with CONFIG_NET_L3_MASTER_DEV. - Default: 0 (disabled) + + Default: 0 (disabled) udp_mem - vector of 3 INTEGERs: min, pressure, max Number of pages allowed for queueing by all UDP sockets. @@ -849,15 +944,18 @@ 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. + Default: 4K 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. + Default: 4K -RAW variables: +RAW variables +============= raw_l3mdev_accept - BOOLEAN Enabling this option allows a "global" bound socket to work @@ -865,9 +963,11 @@ raw_l3mdev_accept - BOOLEAN being received regardless of the L3 domain in which they originated. Only valid when the kernel was compiled with CONFIG_NET_L3_MASTER_DEV. + Default: 1 (enabled) -CIPSOv4 Variables: +CIPSOv4 Variables +================= cipso_cache_enable - BOOLEAN If set, enable additions to and lookups from the CIPSO label mapping @@ -875,6 +975,7 @@ cipso_cache_enable - BOOLEAN 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 @@ -884,6 +985,7 @@ cipso_cache_bucket_size - INTEGER 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 @@ -891,6 +993,7 @@ cipso_rbm_optfmt - BOOLEAN 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 @@ -900,9 +1003,11 @@ cipso_rbm_structvalid - BOOLEAN 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 -IP Variables: +IP Variables +============ ip_local_port_range - 2 INTEGERS Defines the local port range that is used by TCP and UDP to @@ -931,12 +1036,12 @@ ip_local_reserved_ports - list of comma separated ranges assignments. You can reserve ports which are not in the current - ip_local_port_range, e.g.: + ip_local_port_range, e.g.:: - $ cat /proc/sys/net/ipv4/ip_local_port_range - 32000 60999 - $ cat /proc/sys/net/ipv4/ip_local_reserved_ports - 8080,9148 + $ cat /proc/sys/net/ipv4/ip_local_port_range + 32000 60999 + $ 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 @@ -956,6 +1061,7 @@ ip_unprivileged_port_start - INTEGER 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_autobind_reuse - BOOLEAN @@ -972,6 +1078,7 @@ ip_dynaddr - BOOLEAN If set to a non-zero value larger than 1, a kernel log message will be printed when dynamic address rewriting occurs. + Default: 0 ip_early_demux - BOOLEAN @@ -981,6 +1088,7 @@ ip_early_demux - BOOLEAN It may add an additional cost for pure routing workloads that reduces overall throughput, in such case you should disable it. + Default: 1 ping_group_range - 2 INTEGERS @@ -992,21 +1100,25 @@ ping_group_range - 2 INTEGERS tcp_early_demux - BOOLEAN Enable early demux for established TCP sockets. + Default: 1 udp_early_demux - BOOLEAN Enable early demux for connected UDP sockets. Disable this if your system could experience more unconnected load. + Default: 1 icmp_echo_ignore_all - BOOLEAN If set non-zero, then the kernel will ignore all ICMP ECHO requests sent to it. + Default: 0 icmp_echo_ignore_broadcasts - BOOLEAN If set non-zero, then the kernel will ignore all ICMP ECHO and TIMESTAMP requests sent to it via broadcast/multicast. + Default: 1 icmp_ratelimit - INTEGER @@ -1016,46 +1128,55 @@ icmp_ratelimit - INTEGER otherwise the minimal space between responses in milliseconds. Note that another sysctl, icmp_msgs_per_sec limits the number of ICMP packets sent on all targets. + Default: 1000 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. + Default: 1000 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 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 * + 3 Destination Unreachable [1]_ + 4 Source Quench [1]_ 5 Redirect 8 Echo Request - B Time Exceeded * - C Parameter Problem * + B Time Exceeded [1]_ + C Parameter Problem [1]_ 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) + .. [1] These are rate limited by default (see default mask above) icmp_ignore_bogus_error_responses - BOOLEAN Some routers violate RFC1122 by sending bogus responses to broadcast frames. Such violations are normally logged via a kernel warning. If this is set to TRUE, the kernel will not give such warnings, which will avoid log file clutter. + Default: 1 icmp_errors_use_inbound_ifaddr - BOOLEAN @@ -1100,32 +1221,39 @@ igmp_max_memberships - INTEGER igmp_max_msf - INTEGER Maximum number of addresses allowed in the source filter list for a multicast group. + Default: 10 igmp_qrv - INTEGER 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) force_igmp_version - INTEGER - 0 - (default) No enforcement of a IGMP version, IGMPv1/v2 fallback - allowed. Will back to IGMPv3 mode again if all IGMPv1/v2 Querier - Present timer expires. - 1 - Enforce to use IGMP version 1. Will also reply IGMPv1 report if - receive IGMPv2/v3 query. - 2 - Enforce to use IGMP version 2. Will fallback to IGMPv1 if receive - IGMPv1 query message. Will reply report if receive IGMPv3 query. - 3 - Enforce to use IGMP version 3. The same react with default 0. + - 0 - (default) No enforcement of a IGMP version, IGMPv1/v2 fallback + allowed. Will back to IGMPv3 mode again if all IGMPv1/v2 Querier + Present timer expires. + - 1 - Enforce to use IGMP version 1. Will also reply IGMPv1 report if + receive IGMPv2/v3 query. + - 2 - Enforce to use IGMP version 2. Will fallback to IGMPv1 if receive + IGMPv1 query message. Will reply report if receive IGMPv3 query. + - 3 - Enforce to use IGMP version 3. The same react with default 0. + + .. note:: - Note: this is not the same with force_mld_version because IGMPv3 RFC3376 - Security Considerations does not have clear description that we could - ignore other version messages completely as MLDv2 RFC3810. So make - this value as default 0 is recommended. + this is not the same with force_mld_version because IGMPv3 RFC3376 + Security Considerations does not have clear description that we could + ignore other version messages completely as MLDv2 RFC3810. So make + this value as default 0 is recommended. -conf/interface/* changes special settings per interface (where -"interface" is the name of your network interface) +``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 +``conf/all/*`` + is special, changes the settings for all interfaces log_martians - BOOLEAN Log packets with impossible addresses to kernel log. @@ -1136,14 +1264,21 @@ log_martians - BOOLEAN accept_redirects - BOOLEAN Accept ICMP redirect messages. accept_redirects for the interface will be enabled if: + - both conf/{all,interface}/accept_redirects are TRUE in the case forwarding for the interface is enabled + or + - at least one of conf/{all,interface}/accept_redirects is TRUE in the case forwarding for the interface is disabled + accept_redirects for the interface will be disabled otherwise - default TRUE (host) - FALSE (router) + + default: + + - TRUE (host) + - FALSE (router) forwarding - BOOLEAN Enable IP forwarding on this interface. This controls whether packets @@ -1168,12 +1303,14 @@ medium_id - INTEGER 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 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). @@ -1186,6 +1323,7 @@ proxy_arp_pvlan - BOOLEAN 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. @@ -1194,26 +1332,33 @@ proxy_arp_pvlan - BOOLEAN shared_media - BOOLEAN Send(router) or accept(host) RFC1620 shared media redirects. Overrides secure_redirects. + shared_media for the interface will be enabled if at least one of conf/{all,interface}/shared_media is set to TRUE, it will be disabled otherwise + default TRUE secure_redirects - BOOLEAN Accept ICMP redirect messages only to gateways listed in the interface's current gateway list. Even if disabled, RFC1122 redirect rules still apply. + Overridden by shared_media. + 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 @@ -1222,15 +1367,20 @@ bootp_relay - BOOLEAN 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) + + default + + - TRUE (router) + - FALSE (host) accept_local - BOOLEAN Accept packets with local source addresses. In combination with @@ -1241,18 +1391,19 @@ accept_local - BOOLEAN 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 rp_filter - INTEGER - 0 - No source validation. - 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. + - 0 - No source validation. + - 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. Current recommended practice in RFC3704 is to enable strict mode to prevent IP spoofing from DDos attacks. If using asymmetric routing @@ -1265,19 +1416,19 @@ rp_filter - INTEGER 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. + - 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, @@ -1287,26 +1438,27 @@ 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. + + - 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. @@ -1317,32 +1469,37 @@ arp_announce - INTEGER 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 + + - 0 - (default): reply for any local target IP address, configured + on any interface + - 1 - reply only if the target IP address is local address + configured on the incoming interface + - 2 - reply only if the target IP address is local address + configured on the incoming interface and both with the + sender's IP address are part from same subnet on this interface + - 3 - do not reply for local addresses configured with scope host, + only resolutions for global and link addresses are replied + - 4-7 - reserved + - 8 - do not reply for all local addresses The max value from conf/{all,interface}/arp_ignore is used when ARP request is received on the {interface} arp_notify - BOOLEAN Define mode for notification of address and device changes. - 0 - (default): do nothing - 1 - Generate gratuitous arp requests when device is brought up - or hardware address changes. + + == ========================================================== + 0 (default): do nothing + 1 Generate gratuitous arp requests when device is brought up + or hardware address changes. + == ========================================================== arp_accept - BOOLEAN 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 + + - 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. @@ -1378,11 +1535,13 @@ disable_xfrm - BOOLEAN 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) igmpv3_unsolicited_report_interval - INTEGER The interval in milliseconds in which the next unsolicited IGMPv3 report retransmit will take place. + Default: 1000 (1 seconds) promote_secondaries - BOOLEAN @@ -1393,19 +1552,23 @@ promote_secondaries - BOOLEAN 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) 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) tag - INTEGER Allows you to write a number, which can be used as required. + Default value is 0. xfrm4_gc_thresh - INTEGER @@ -1417,21 +1580,24 @@ xfrm4_gc_thresh - INTEGER igmp_link_local_mcast_reports - BOOLEAN Enable IGMP reports for link local multicast groups in the 224.0.0.X range. + Default TRUE Alexey Kuznetsov. kuznet@ms2.inr.ac.ru Updated by: -Andi Kleen -ak@muc.de -Nicolas Delon -delon.nicolas@wanadoo.fr +- Andi Kleen + ak@muc.de +- Nicolas Delon + delon.nicolas@wanadoo.fr -/proc/sys/net/ipv6/* Variables: + +/proc/sys/net/ipv6/* Variables +============================== IPv6 has no global variables such as tcp_*. tcp_* settings under ipv4/ also apply to IPv6 [XXX?]. @@ -1440,8 +1606,9 @@ bindv6only - BOOLEAN Default value for IPV6_V6ONLY socket option, which restricts use of the IPv6 socket to IPv6 communication only. - TRUE: disable IPv4-mapped address feature - FALSE: enable IPv4-mapped address feature + + - TRUE: disable IPv4-mapped address feature + - FALSE: enable IPv4-mapped address feature Default: FALSE (as specified in RFC3493) @@ -1449,8 +1616,10 @@ 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 + + - TRUE: enabled + - FALSE: disabled + Default: TRUE auto_flowlabels - INTEGER @@ -1458,22 +1627,28 @@ auto_flowlabels - INTEGER packet. This allows intermediate devices, such as routers, to identify packet flows for mechanisms like Equal Cost Multipath Routing (see RFC 6438). - 0: automatic flow labels are completely disabled - 1: automatic flow labels are enabled by default, they can be + + = =========================================================== + 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 + 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 + 3 automatic flow labels are enabled and enforced, they cannot be disabled by the socket option + = =========================================================== + Default: 1 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 + + - TRUE: enabled + - FALSE: disabled + Default: true flowlabel_reflect - INTEGER @@ -1483,49 +1658,59 @@ flowlabel_reflect - INTEGER https://tools.ietf.org/html/draft-wang-6man-flow-label-reflection-01 This is a bitmask. - 1: enabled for established flows - Note that this prevents automatic flowlabel changes, as done - in "tcp: change IPv6 flow-label upon receiving spurious retransmission" - and "tcp: Change txhash on every SYN and RTO retransmit" + - 1: enabled for established flows + + Note that this prevents automatic flowlabel changes, as done + in "tcp: change IPv6 flow-label upon receiving spurious retransmission" + and "tcp: Change txhash on every SYN and RTO retransmit" - 2: enabled for TCP RESET packets (no active listener) - If set, a RST packet sent in response to a SYN packet on a closed - port will reflect the incoming flow label. + - 2: enabled for TCP RESET packets (no active listener) + If set, a RST packet sent in response to a SYN packet on a closed + port will reflect the incoming flow label. - 4: enabled for ICMPv6 echo reply messages. + - 4: enabled for ICMPv6 echo reply messages. Default: 0 fib_multipath_hash_policy - INTEGER Controls which hash policy to use for multipath routes. + Default: 0 (Layer 3) + Possible values: - 0 - Layer 3 (source and destination addresses plus flow label) - 1 - Layer 4 (standard 5-tuple) - 2 - Layer 3 or inner Layer 3 if present + + - 0 - Layer 3 (source and destination addresses plus flow label) + - 1 - Layer 4 (standard 5-tuple) + - 2 - Layer 3 or inner Layer 3 if present anycast_src_echo_reply - BOOLEAN Controls the use of anycast addresses as source addresses for ICMPv6 echo reply - TRUE: enabled - FALSE: disabled + + - TRUE: enabled + - FALSE: disabled + Default: FALSE 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) 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) max_dst_opts_number - INTEGER @@ -1533,6 +1718,7 @@ max_dst_opts_number - INTEGER options extension header. If this value is less than zero then unknown options are disallowed and the number of known TLVs allowed is the absolute value of this number. + Default: 8 max_hbh_opts_number - INTEGER @@ -1540,16 +1726,19 @@ max_hbh_opts_number - INTEGER options extension header. If this value is less than zero then unknown options are disallowed and the number of known TLVs allowed is the absolute value of this number. + Default: 8 max_dst_opts_length - INTEGER Maximum length allowed for a Destination options extension header. + Default: INT_MAX (unlimited) max_hbh_length - INTEGER Maximum length allowed for a Hop-by-Hop options extension header. + Default: INT_MAX (unlimited) skip_notify_on_dev_down - BOOLEAN @@ -1558,6 +1747,7 @@ skip_notify_on_dev_down - BOOLEAN generate this message; IPv6 does by default. Setting this sysctl to true skips the message, making IPv4 and IPv6 on par in relying on userspace caches to track link events and evict routes. + Default: false (generate message) nexthop_compat_mode - BOOLEAN @@ -1592,18 +1782,20 @@ seg6_flowlabel - INTEGER Controls the behaviour of computing the flowlabel of outer IPv6 header in case of SR T.encaps - -1 set flowlabel to zero. - 0 copy flowlabel from Inner packet in case of Inner IPv6 - (Set flowlabel to 0 in case IPv4/L2) - 1 Compute the flowlabel using seg6_make_flowlabel() + == ======================================================= + -1 set flowlabel to zero. + 0 copy flowlabel from Inner packet in case of Inner IPv6 + (Set flowlabel to 0 in case IPv4/L2) + 1 Compute the flowlabel using seg6_make_flowlabel() + == ======================================================= Default is 0. -conf/default/*: +``conf/default/*``: Change the interface-specific default settings. -conf/all/*: +``conf/all/*``: Change all the interface-specific settings. [XXX: Other special features than forwarding?] @@ -1627,9 +1819,10 @@ fwmark_reflect - BOOLEAN 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 -conf/interface/*: +``conf/interface/*``: Change special settings per interface. The functional behaviour for certain settings is different @@ -1644,31 +1837,40 @@ accept_ra - INTEGER transmitted. 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. - Functional default: enabled if local forwarding is disabled. - disabled if local forwarding is enabled. + == =========================================================== + 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. + == =========================================================== + + Functional default: + + - enabled if local forwarding is disabled. + - disabled if local forwarding is enabled. accept_ra_defrtr - BOOLEAN Learn default router in Router Advertisement. - Functional default: enabled if accept_ra is enabled. - disabled if accept_ra is disabled. + Functional default: + + - enabled if accept_ra is enabled. + - disabled if accept_ra is disabled. 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. + 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. + + - enabled if accept_ra_from_local is enabled + on a specific interface. + - disabled if accept_ra_from_local is disabled + on a specific interface. accept_ra_min_hop_limit - INTEGER Minimum hop limit Information in Router Advertisement. @@ -1681,8 +1883,10 @@ accept_ra_min_hop_limit - INTEGER accept_ra_pinfo - BOOLEAN Learn Prefix Information in Router Advertisement. - Functional default: enabled if accept_ra is enabled. - disabled if accept_ra is disabled. + Functional default: + + - enabled if accept_ra is enabled. + - disabled if accept_ra is disabled. accept_ra_rt_info_min_plen - INTEGER Minimum prefix length of Route Information in RA. @@ -1690,8 +1894,10 @@ accept_ra_rt_info_min_plen - INTEGER Route Information w/ prefix smaller than this variable shall be ignored. - Functional default: 0 if accept_ra_rtr_pref is enabled. - -1 if accept_ra_rtr_pref is disabled. + Functional default: + + * 0 if accept_ra_rtr_pref is enabled. + * -1 if accept_ra_rtr_pref is disabled. accept_ra_rt_info_max_plen - INTEGER Maximum prefix length of Route Information in RA. @@ -1699,33 +1905,41 @@ accept_ra_rt_info_max_plen - INTEGER Route Information w/ prefix larger than this variable shall be ignored. - Functional default: 0 if accept_ra_rtr_pref is enabled. - -1 if accept_ra_rtr_pref is disabled. + Functional default: + + * 0 if accept_ra_rtr_pref is enabled. + * -1 if accept_ra_rtr_pref is disabled. accept_ra_rtr_pref - BOOLEAN Accept Router Preference in RA. - Functional default: enabled if accept_ra is enabled. - disabled if accept_ra is disabled. + Functional default: + + - enabled if accept_ra is enabled. + - disabled if accept_ra is disabled. 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. + Functional default: + + - enabled if accept_ra is enabled. + - disabled if accept_ra is disabled. accept_redirects - BOOLEAN Accept Redirects. - Functional default: enabled if local forwarding is disabled. - disabled if local forwarding is enabled. + Functional default: + + - enabled if local forwarding is disabled. + - disabled if local forwarding is enabled. accept_source_route - INTEGER Accept source routing (routing extension header). - >= 0: Accept only routing header type 2. - < 0: Do not accept routing header. + - >= 0: Accept only routing header type 2. + - < 0: Do not accept routing header. Default: 0 @@ -1733,24 +1947,30 @@ autoconf - BOOLEAN Autoconfigure addresses using Prefix Information in Router Advertisements. - Functional default: enabled if accept_ra_pinfo is enabled. - disabled if accept_ra_pinfo is disabled. + Functional default: + + - enabled if accept_ra_pinfo is enabled. + - disabled if accept_ra_pinfo is disabled. dad_transmits - INTEGER The amount of Duplicate Address Detection probes to send. + Default: 1 forwarding - INTEGER Configure interface-specific Host/Router behaviour. - Note: It is recommended to have the same setting on all - interfaces; mixed router/host scenarios are rather uncommon. + .. note:: + + It is recommended to have the same setting on all + interfaces; mixed router/host scenarios are rather uncommon. Possible values are: - 0 Forwarding disabled - 1 Forwarding enabled - FALSE (0): + - 0 Forwarding disabled + - 1 Forwarding enabled + + **FALSE (0)**: By default, Host behaviour is assumed. This means: @@ -1761,7 +1981,7 @@ forwarding - INTEGER Advertisements (and do autoconfiguration). 4. If accept_redirects is TRUE (default), accept Redirects. - TRUE (1): + **TRUE (1)**: If local forwarding is enabled, Router behaviour is assumed. This means exactly the reverse from the above: @@ -1772,19 +1992,22 @@ forwarding - INTEGER 4. Redirects are ignored. Default: 0 (disabled) if global forwarding is disabled (default), - otherwise 1 (enabled). + otherwise 1 (enabled). hop_limit - INTEGER Default Hop Limit to set. + Default: 64 mtu - INTEGER Default Maximum Transfer Unit + Default: 1280 (IPv6 required minimum) 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 router_probe_interval - INTEGER @@ -1796,15 +2019,18 @@ router_probe_interval - INTEGER router_solicitation_delay - INTEGER Number of seconds to wait after interface is brought up before sending Router Solicitations. + Default: 1 router_solicitation_interval - INTEGER Number of seconds to wait between Router Solicitations. + Default: 4 router_solicitations - INTEGER Number of Router Solicitations to send until assuming no routers are present. + Default: 3 use_oif_addrs_only - BOOLEAN @@ -1816,28 +2042,35 @@ use_oif_addrs_only - BOOLEAN 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) + + * <= 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) 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 + + * >0 : enabled + * 0 : system default + * <0 : disabled Default: 0 (addresses are removed) @@ -1846,11 +2079,13 @@ max_desync_factor - INTEGER that ensures that clients don't synchronize with each other and generate new addresses at exactly the same time. value is in seconds. + Default: 600 regen_max_retry - INTEGER Number of attempts before give up attempting to generate valid temporary addresses. + Default: 5 max_addresses - INTEGER @@ -1858,12 +2093,14 @@ max_addresses - INTEGER 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. + Default: 16 disable_ipv6 - BOOLEAN 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. + Default: FALSE (enable IPv6 operation) When this value is changed from 1 to 0 (IPv6 is being enabled), @@ -1877,10 +2114,13 @@ disable_ipv6 - BOOLEAN 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. + + == ============================================================== + 0 Disable DAD + 1 Enable DAD (default) + 2 Enable DAD, and disable IPv6 operation if MAC-based duplicate + link-local address has been found. + == ============================================================== DAD operation and mode on a given interface will be selected according to the maximum value of conf/{all,interface}/accept_dad. @@ -1888,6 +2128,7 @@ accept_dad - INTEGER 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: @@ -1905,9 +2146,10 @@ force_tllao - BOOLEAN 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. + + * 0 - (default): do nothing + * 1 - Generate unsolicited neighbour advertisements when device is brought + up or hardware address changes. ndisc_tclass - INTEGER The IPv6 Traffic Class to use by default when sending IPv6 Neighbor @@ -1916,33 +2158,38 @@ ndisc_tclass - INTEGER These 8 bits can be interpreted as 6 high order bits holding the DSCP value and 2 low order bits representing ECN (which you probably want to leave cleared). - 0 - (default) + + * 0 - (default) 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) 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 + * 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 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 + + * 1 - (default) discard fragmented neighbor discovery packets + * 0 - allow fragmented neighbor discovery packets optimistic_dad - BOOLEAN Whether to perform Optimistic Duplicate Address Detection (RFC 4429). - 0: disabled (default) - 1: enabled + + * 0: disabled (default) + * 1: enabled Optimistic Duplicate Address Detection for the interface will be enabled if at least one of conf/{all,interface}/optimistic_dad is set to 1, @@ -1953,8 +2200,9 @@ use_optimistic - BOOLEAN 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 + + * 0: disabled (default) + * 1: enabled This will be enabled if at least one of conf/{all,interface}/use_optimistic is set to 1, disabled otherwise. @@ -1976,12 +2224,14 @@ stable_secret - IPv6 address addr_gen_mode - INTEGER Defines how link-local and autoconf addresses are generated. - 0: generate address based on EUI64 (default) - 1: do no generate a link-local address, use EUI64 for addresses generated - from autoconf - 2: generate stable privacy addresses, using the secret from + = ================================================================= + 0 generate address based on EUI64 (default) + 1 do no generate a link-local address, use EUI64 for addresses + generated from autoconf + 2 generate stable privacy addresses, using the secret from stable_secret (RFC7217) - 3: generate stable privacy addresses, using a random secret if unset + 3 generate stable privacy addresses, using a random secret if unset + = ================================================================= drop_unicast_in_l2_multicast - BOOLEAN Drop any unicast IPv6 packets that are received in link-layer @@ -2003,13 +2253,18 @@ enhanced_dad - BOOLEAN detection of duplicates due to loopback of the NS messages that we send. The nonce option will be sent on an interface unless both of conf/{all,interface}/enhanced_dad are set to FALSE. + Default: TRUE -icmp/*: +``icmp/*``: +=========== + ratelimit - INTEGER Limit the maximal rates for sending ICMPv6 messages. + 0 to disable any limiting, otherwise the minimal space between responses in milliseconds. + Default: 1000 ratemask - list of comma separated ranges @@ -2030,16 +2285,19 @@ ratemask - list of comma separated ranges echo_ignore_all - BOOLEAN If set non-zero, then the kernel will ignore all ICMP ECHO requests sent to it over the IPv6 protocol. + Default: 0 echo_ignore_multicast - BOOLEAN If set non-zero, then the kernel will ignore all ICMP ECHO requests sent to it over the IPv6 protocol via multicast. + Default: 0 echo_ignore_anycast - BOOLEAN If set non-zero, then the kernel will ignore all ICMP ECHO requests sent to it over the IPv6 protocol destined to anycast address. + Default: 0 xfrm6_gc_thresh - INTEGER @@ -2055,43 +2313,52 @@ 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. + - 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. + - 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. + - 1 : pass bridged IPv6 traffic to ip6tables' chains. + - 0 : disable this. + Default: 1 bridge-nf-filter-vlan-tagged - BOOLEAN - 1 : pass bridged vlan-tagged ARP/IP/IPv6 traffic to {arp,ip,ip6}tables. - 0 : disable this. + - 1 : pass bridged vlan-tagged ARP/IP/IPv6 traffic to {arp,ip,ip6}tables. + - 0 : disable this. + Default: 0 bridge-nf-filter-pppoe-tagged - BOOLEAN - 1 : pass bridged pppoe-tagged IP/IPv6 traffic to {ip,ip6}tables. - 0 : disable this. + - 1 : pass bridged pppoe-tagged IP/IPv6 traffic to {ip,ip6}tables. + - 0 : disable this. + Default: 0 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. + - 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 -proc/sys/net/sctp/* Variables: +``proc/sys/net/sctp/*`` Variables: +================================== addip_enable - BOOLEAN Enable or disable extension of Dynamic Address Reconfiguration @@ -2156,11 +2423,13 @@ addip_noauth_enable - BOOLEAN we provide this variable to control the enforcement of the authentication requirement. - 1: Allow ADD-IP extension to be used without authentication. This + == =============================================================== + 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 + 0 Enforce the authentication requirement + == =============================================================== Default: 0 @@ -2170,8 +2439,8 @@ auth_enable - BOOLEAN required for secure operation of Dynamic Address Reconfiguration (ADD-IP) extension. - 1: Enable this extension. - 0: Disable this extension. + - 1: Enable this extension. + - 0: Disable this extension. Default: 0 @@ -2179,8 +2448,8 @@ 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 + - 1: Enable extension + - 0: Disable Default: 1 @@ -2282,8 +2551,8 @@ 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 + - 1: Enable cookie lifetime extension. + - 0: Disable Default: 1 @@ -2291,9 +2560,11 @@ 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 configuration of those algorithms at build time (CONFIG_CRYPTO_MD5 and CONFIG_CRYPTO_SHA1). @@ -2312,16 +2583,16 @@ rcvbuf_policy - INTEGER to each association instead of the socket. This prevents the described blocking. - 1: rcvbuf space is per association - 0: rcvbuf space is per socket + - 1: rcvbuf space is per association + - 0: rcvbuf space is per socket 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. + - 1: Send buffer is tracked per association + - 0: Send buffer is tracked per socket. Default: 0 @@ -2354,19 +2625,23 @@ sctp_wmem - vector of 3 INTEGERs: min, default, max 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 + - 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 -/proc/sys/net/core/* +``/proc/sys/net/core/*`` +======================== + Please see: Documentation/admin-guide/sysctl/net.rst for descriptions of these entries. -/proc/sys/net/unix/* +``/proc/sys/net/unix/*`` +======================== + max_dgram_qlen - INTEGER The maximum length of dgram socket receive queue diff --git a/Documentation/networking/snmp_counter.rst b/Documentation/networking/snmp_counter.rst index 10e11099e74a..4edd0d38779e 100644 --- a/Documentation/networking/snmp_counter.rst +++ b/Documentation/networking/snmp_counter.rst @@ -792,7 +792,7 @@ counters to indicate the ACK is skipped in which scenario. The ACK would only be skipped if the received packet is either a SYN packet or it has no data. -.. _sysctl document: https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt +.. _sysctl document: https://www.kernel.org/doc/Documentation/networking/ip-sysctl.rst * TcpExtTCPACKSkippedSynRecv diff --git a/net/Kconfig b/net/Kconfig index df8d8c9bd021..8b1f85820a6b 100644 --- a/net/Kconfig +++ b/net/Kconfig @@ -86,7 +86,7 @@ config INET "Sysctl support" below, you can change various aspects of the behavior of the TCP/IP code by writing to the (virtual) files in /proc/sys/net/ipv4/*; the options are explained in the file - <file:Documentation/networking/ip-sysctl.txt>. + <file:Documentation/networking/ip-sysctl.rst>. Short answer: say Y. diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig index 25a8888826b8..5da4733067fb 100644 --- a/net/ipv4/Kconfig +++ b/net/ipv4/Kconfig @@ -49,7 +49,7 @@ config IP_ADVANCED_ROUTER Note that some distributions enable it in startup scripts. For details about rp_filter strict and loose mode read - <file:Documentation/networking/ip-sysctl.txt>. + <file:Documentation/networking/ip-sysctl.rst>. If unsure, say N here. diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index fc61f51d87a3..956a806649f7 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -853,7 +853,7 @@ static bool icmp_unreach(struct sk_buff *skb) case ICMP_FRAG_NEEDED: /* for documentation of the ip_no_pmtu_disc * values please see - * Documentation/networking/ip-sysctl.txt + * Documentation/networking/ip-sysctl.rst */ switch (net->ipv4.sysctl_ip_no_pmtu_disc) { default: |