@@ -148,9 +148,9 @@ tcp_available_congestion_control - STRING
148148 but not loaded.
149149
150150tcp_base_mss - INTEGER
151- The initial value of search_low to be used by Packetization Layer
152- Path MTU Discovery (MTU probing). If MTU probing is enabled,
153- this is the inital MSS used by the connection.
151+ The initial value of search_low to be used by the packetization layer
152+ Path MTU discovery (MTU probing). If MTU probing is enabled,
153+ this is the initial MSS used by the connection.
154154
155155tcp_congestion_control - STRING
156156 Set the congestion control algorithm to be used for new
@@ -185,10 +185,9 @@ tcp_frto - INTEGER
185185 timeouts. It is particularly beneficial in wireless environments
186186 where packet loss is typically due to random radio interference
187187 rather than intermediate router congestion. F-RTO is sender-side
188- only modification. Therefore it does not require any support from
189- the peer, but in a typical case, however, where wireless link is
190- the local access link and most of the data flows downlink, the
191- faraway servers should have F-RTO enabled to take advantage of it.
188+ only modification. Therefore it does not require any support from
189+ the peer.
190+
192191 If set to 1, basic version is enabled. 2 enables SACK enhanced
193192 F-RTO if flow uses SACK. The basic version can be used also when
194193 SACK is in use though scenario(s) with it exists where F-RTO
@@ -276,7 +275,7 @@ tcp_mem - vector of 3 INTEGERs: min, pressure, max
276275 memory.
277276
278277tcp_moderate_rcvbuf - BOOLEAN
279- If set, TCP performs receive buffer autotuning , attempting to
278+ If set, TCP performs receive buffer auto-tuning , attempting to
280279 automatically size the buffer (no greater than tcp_rmem[2]) to
281280 match the size required by the path for full throughput. Enabled by
282281 default.
@@ -336,16 +335,18 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max
336335 pressure.
337336 Default: 8K
338337
339- default: default size of receive buffer used by TCP sockets.
338+ default: initial size of receive buffer used by TCP sockets.
340339 This value overrides net.core.rmem_default used by other protocols.
341340 Default: 87380 bytes. This value results in window of 65535 with
342341 default setting of tcp_adv_win_scale and tcp_app_win:0 and a bit
343342 less for default tcp_app_win. See below about these variables.
344343
345344 max: maximal size of receive buffer allowed for automatically
346345 selected receiver buffers for TCP socket. This value does not override
347- net.core.rmem_max, "static" selection via SO_RCVBUF does not use this.
348- Default: 87380*2 bytes.
346+ net.core.rmem_max. Calling setsockopt() with SO_RCVBUF disables
347+ automatic tuning of that socket's receive buffer size, in which
348+ case this value is ignored.
349+ Default: between 87380B and 4MB, depending on RAM size.
349350
350351tcp_sack - BOOLEAN
351352 Enable select acknowledgments (SACKS).
@@ -358,7 +359,7 @@ tcp_slow_start_after_idle - BOOLEAN
358359 Default: 1
359360
360361tcp_stdurg - BOOLEAN
361- Use the Host requirements interpretation of the TCP urg pointer field.
362+ Use the Host requirements interpretation of the TCP urgent pointer field.
362363 Most hosts use the older BSD interpretation, so if you turn this on
363364 Linux might not communicate correctly with them.
364365 Default: FALSE
@@ -371,12 +372,12 @@ tcp_synack_retries - INTEGER
371372tcp_syncookies - BOOLEAN
372373 Only valid when the kernel was compiled with CONFIG_SYNCOOKIES
373374 Send out syncookies when the syn backlog queue of a socket
374- overflows. This is to prevent against the common 'syn flood attack'
375+ overflows. This is to prevent against the common 'SYN flood attack'
375376 Default: FALSE
376377
377378 Note, that syncookies is fallback facility.
378379 It MUST NOT be used to help highly loaded servers to stand
379- against legal connection rate. If you see synflood warnings
380+ against legal connection rate. If you see SYN flood warnings
380381 in your logs, but investigation shows that they occur
381382 because of overload with legal connections, you should tune
382383 another parameters until this warning disappear.
@@ -386,7 +387,7 @@ tcp_syncookies - BOOLEAN
386387 to use TCP extensions, can result in serious degradation
387388 of some services (f.e. SMTP relaying), visible not by you,
388389 but your clients and relays, contacting you. While you see
389- synflood warnings in logs not being really flooded, your server
390+ SYN flood warnings in logs not being really flooded, your server
390391 is seriously misconfigured.
391392
392393tcp_syn_retries - INTEGER
@@ -419,19 +420,21 @@ tcp_window_scaling - BOOLEAN
419420 Enable window scaling as defined in RFC1323.
420421
421422tcp_wmem - vector of 3 INTEGERs: min, default, max
422- min: Amount of memory reserved for send buffers for TCP socket .
423+ min: Amount of memory reserved for send buffers for TCP sockets .
423424 Each TCP socket has rights to use it due to fact of its birth.
424425 Default: 4K
425426
426- default: Amount of memory allowed for send buffers for TCP socket
427- by default. This value overrides net.core.wmem_default used
428- by other protocols, it is usually lower than net.core.wmem_default.
427+ default: initial size of send buffer used by TCP sockets. This
428+ value overrides net.core.wmem_default used by other protocols.
429+ It is usually lower than net.core.wmem_default.
429430 Default: 16K
430431
431- max: Maximal amount of memory allowed for automatically selected
432- send buffers for TCP socket. This value does not override
433- net.core.wmem_max, "static" selection via SO_SNDBUF does not use this.
434- Default: 128K
432+ max: Maximal amount of memory allowed for automatically tuned
433+ send buffers for TCP sockets. This value does not override
434+ net.core.wmem_max. Calling setsockopt() with SO_SNDBUF disables
435+ automatic tuning of that socket's send buffer size, in which case
436+ this value is ignored.
437+ Default: between 64K and 4MB, depending on RAM size.
435438
436439tcp_workaround_signed_windows - BOOLEAN
437440 If set, assume no receipt of a window scaling option means the
@@ -1060,24 +1063,193 @@ bridge-nf-filter-pppoe-tagged - BOOLEAN
10601063 Default: 1
10611064
10621065
1063- UNDOCUMENTED:
1066+ proc/sys/net/sctp/* Variables:
1067+
1068+ addip_enable - BOOLEAN
1069+ Enable or disable extension of Dynamic Address Reconfiguration
1070+ (ADD-IP) functionality specified in RFC5061. This extension provides
1071+ the ability to dynamically add and remove new addresses for the SCTP
1072+ associations.
1073+
1074+ 1: Enable extension.
1075+
1076+ 0: Disable extension.
1077+
1078+ Default: 0
1079+
1080+ addip_noauth_enable - BOOLEAN
1081+ Dynamic Address Reconfiguration (ADD-IP) requires the use of
1082+ authentication to protect the operations of adding or removing new
1083+ addresses. This requirement is mandated so that unauthorized hosts
1084+ would not be able to hijack associations. However, older
1085+ implementations may not have implemented this requirement while
1086+ allowing the ADD-IP extension. For reasons of interoperability,
1087+ we provide this variable to control the enforcement of the
1088+ authentication requirement.
1089+
1090+ 1: Allow ADD-IP extension to be used without authentication. This
1091+ should only be set in a closed environment for interoperability
1092+ with older implementations.
1093+
1094+ 0: Enforce the authentication requirement
1095+
1096+ Default: 0
1097+
1098+ auth_enable - BOOLEAN
1099+ Enable or disable Authenticated Chunks extension. This extension
1100+ provides the ability to send and receive authenticated chunks and is
1101+ required for secure operation of Dynamic Address Reconfiguration
1102+ (ADD-IP) extension.
1103+
1104+ 1: Enable this extension.
1105+ 0: Disable this extension.
1106+
1107+ Default: 0
1108+
1109+ prsctp_enable - BOOLEAN
1110+ Enable or disable the Partial Reliability extension (RFC3758) which
1111+ is used to notify peers that a given DATA should no longer be expected.
1112+
1113+ 1: Enable extension
1114+ 0: Disable
1115+
1116+ Default: 1
1117+
1118+ max_burst - INTEGER
1119+ The limit of the number of new packets that can be initially sent. It
1120+ controls how bursty the generated traffic can be.
1121+
1122+ Default: 4
1123+
1124+ association_max_retrans - INTEGER
1125+ Set the maximum number for retransmissions that an association can
1126+ attempt deciding that the remote end is unreachable. If this value
1127+ is exceeded, the association is terminated.
1128+
1129+ Default: 10
1130+
1131+ max_init_retransmits - INTEGER
1132+ The maximum number of retransmissions of INIT and COOKIE-ECHO chunks
1133+ that an association will attempt before declaring the destination
1134+ unreachable and terminating.
1135+
1136+ Default: 8
1137+
1138+ path_max_retrans - INTEGER
1139+ The maximum number of retransmissions that will be attempted on a given
1140+ path. Once this threshold is exceeded, the path is considered
1141+ unreachable, and new traffic will use a different path when the
1142+ association is multihomed.
1143+
1144+ Default: 5
1145+
1146+ rto_initial - INTEGER
1147+ The initial round trip timeout value in milliseconds that will be used
1148+ in calculating round trip times. This is the initial time interval
1149+ for retransmissions.
1150+
1151+ Default: 3000
10641152
1065- dev_weight FIXME
1066- discovery_slots FIXME
1067- discovery_timeout FIXME
1068- fast_poll_increase FIXME
1069- ip6_queue_maxlen FIXME
1070- lap_keepalive_time FIXME
1071- lo_cong FIXME
1072- max_baud_rate FIXME
1073- max_dgram_qlen FIXME
1074- max_noreply_time FIXME
1075- max_tx_data_size FIXME
1076- max_tx_window FIXME
1077- min_tx_turn_time FIXME
1078- mod_cong FIXME
1079- no_cong FIXME
1080- no_cong_thresh FIXME
1081- slot_timeout FIXME
1082- warn_noreply_time FIXME
1153+ rto_max - INTEGER
1154+ The maximum value (in milliseconds) of the round trip timeout. This
1155+ is the largest time interval that can elapse between retransmissions.
1156+
1157+ Default: 60000
1158+
1159+ rto_min - INTEGER
1160+ The minimum value (in milliseconds) of the round trip timeout. This
1161+ is the smallest time interval the can elapse between retransmissions.
1162+
1163+ Default: 1000
1164+
1165+ hb_interval - INTEGER
1166+ The interval (in milliseconds) between HEARTBEAT chunks. These chunks
1167+ are sent at the specified interval on idle paths to probe the state of
1168+ a given path between 2 associations.
1169+
1170+ Default: 30000
1171+
1172+ sack_timeout - INTEGER
1173+ The amount of time (in milliseconds) that the implementation will wait
1174+ to send a SACK.
1175+
1176+ Default: 200
1177+
1178+ valid_cookie_life - INTEGER
1179+ The default lifetime of the SCTP cookie (in milliseconds). The cookie
1180+ is used during association establishment.
1181+
1182+ Default: 60000
1183+
1184+ cookie_preserve_enable - BOOLEAN
1185+ Enable or disable the ability to extend the lifetime of the SCTP cookie
1186+ that is used during the establishment phase of SCTP association
1187+
1188+ 1: Enable cookie lifetime extension.
1189+ 0: Disable
1190+
1191+ Default: 1
1192+
1193+ rcvbuf_policy - INTEGER
1194+ Determines if the receive buffer is attributed to the socket or to
1195+ association. SCTP supports the capability to create multiple
1196+ associations on a single socket. When using this capability, it is
1197+ possible that a single stalled association that's buffering a lot
1198+ of data may block other associations from delivering their data by
1199+ consuming all of the receive buffer space. To work around this,
1200+ the rcvbuf_policy could be set to attribute the receiver buffer space
1201+ to each association instead of the socket. This prevents the described
1202+ blocking.
1203+
1204+ 1: rcvbuf space is per association
1205+ 0: recbuf space is per socket
1206+
1207+ Default: 0
1208+
1209+ sndbuf_policy - INTEGER
1210+ Similar to rcvbuf_policy above, this applies to send buffer space.
1211+
1212+ 1: Send buffer is tracked per association
1213+ 0: Send buffer is tracked per socket.
1214+
1215+ Default: 0
1216+
1217+ sctp_mem - vector of 3 INTEGERs: min, pressure, max
1218+ Number of pages allowed for queueing by all SCTP sockets.
1219+
1220+ min: Below this number of pages SCTP is not bothered about its
1221+ memory appetite. When amount of memory allocated by SCTP exceeds
1222+ this number, SCTP starts to moderate memory usage.
1223+
1224+ pressure: This value was introduced to follow format of tcp_mem.
1225+
1226+ max: Number of pages allowed for queueing by all SCTP sockets.
1227+
1228+ Default is calculated at boot time from amount of available memory.
1229+
1230+ sctp_rmem - vector of 3 INTEGERs: min, default, max
1231+ See tcp_rmem for a description.
1232+
1233+ sctp_wmem - vector of 3 INTEGERs: min, default, max
1234+ See tcp_wmem for a description.
1235+
1236+ UNDOCUMENTED:
10831237
1238+ /proc/sys/net/core/*
1239+ dev_weight FIXME
1240+
1241+ /proc/sys/net/unix/*
1242+ max_dgram_qlen FIXME
1243+
1244+ /proc/sys/net/irda/*
1245+ fast_poll_increase FIXME
1246+ warn_noreply_time FIXME
1247+ discovery_slots FIXME
1248+ slot_timeout FIXME
1249+ max_baud_rate FIXME
1250+ discovery_timeout FIXME
1251+ lap_keepalive_time FIXME
1252+ max_noreply_time FIXME
1253+ max_tx_data_size FIXME
1254+ max_tx_window FIXME
1255+ min_tx_turn_time FIXME
0 commit comments