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@@ -148,9 +148,9 @@ tcp_available_congestion_control - STRING
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but not loaded.
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tcp_base_mss - INTEGER
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- The initial value of search_low to be used by Packetization Layer
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- Path MTU Discovery (MTU probing). If MTU probing is enabled,
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- this is the inital MSS used by the connection.
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+ The initial value of search_low to be used by the packetization layer
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+ Path MTU discovery (MTU probing). If MTU probing is enabled,
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+ this is the initial MSS used by the connection.
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tcp_congestion_control - STRING
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Set the congestion control algorithm to be used for new
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@@ -185,10 +185,9 @@ tcp_frto - INTEGER
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timeouts. It is particularly beneficial in wireless environments
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where packet loss is typically due to random radio interference
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rather than intermediate router congestion. F-RTO is sender-side
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- only modification. Therefore it does not require any support from
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- the peer, but in a typical case, however, where wireless link is
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- the local access link and most of the data flows downlink, the
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- faraway servers should have F-RTO enabled to take advantage of it.
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+ only modification. Therefore it does not require any support from
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+ the peer.
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+
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If set to 1, basic version is enabled. 2 enables SACK enhanced
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F-RTO if flow uses SACK. The basic version can be used also when
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SACK is in use though scenario(s) with it exists where F-RTO
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@@ -276,7 +275,7 @@ tcp_mem - vector of 3 INTEGERs: min, pressure, max
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memory.
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tcp_moderate_rcvbuf - BOOLEAN
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- If set, TCP performs receive buffer autotuning, attempting to
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+ 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
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match the size required by the path for full throughput. Enabled by
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default.
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@@ -336,7 +335,7 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max
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pressure.
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Default: 8K
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- default: default size of receive buffer used by TCP sockets.
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+ default: initial size of receive buffer used by TCP sockets.
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This value overrides net.core.rmem_default used by other protocols.
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Default: 87380 bytes. This value results in window of 65535 with
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default setting of tcp_adv_win_scale and tcp_app_win:0 and a bit
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@@ -344,8 +343,10 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max
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max: maximal size of receive buffer allowed for automatically
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selected receiver buffers for TCP socket. This value does not override
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- net.core.rmem_max, "static" selection via SO_RCVBUF does not use this.
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- Default: 87380*2 bytes.
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+ net.core.rmem_max. Calling setsockopt() with SO_RCVBUF disables
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+ automatic tuning of that socket's receive buffer size, in which
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+ case this value is ignored.
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+ Default: between 87380B and 4MB, depending on RAM size.
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tcp_sack - BOOLEAN
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Enable select acknowledgments (SACKS).
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@@ -358,7 +359,7 @@ tcp_slow_start_after_idle - BOOLEAN
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Default: 1
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tcp_stdurg - BOOLEAN
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- Use the Host requirements interpretation of the TCP urg pointer field.
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+ Use the Host requirements interpretation of the TCP urgent pointer field.
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Most hosts use the older BSD interpretation, so if you turn this on
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Linux might not communicate correctly with them.
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Default: FALSE
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@@ -371,12 +372,12 @@ tcp_synack_retries - INTEGER
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tcp_syncookies - BOOLEAN
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Only valid when the kernel was compiled with CONFIG_SYNCOOKIES
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Send out syncookies when the syn backlog queue of a socket
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- overflows. This is to prevent against the common 'syn flood attack'
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+ overflows. This is to prevent against the common 'SYN flood attack'
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Default: FALSE
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Note, that syncookies is fallback facility.
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It MUST NOT be used to help highly loaded servers to stand
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- against legal connection rate. If you see synflood warnings
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+ against legal connection rate. If you see SYN flood warnings
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in your logs, but investigation shows that they occur
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because of overload with legal connections, you should tune
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another parameters until this warning disappear.
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@@ -386,7 +387,7 @@ tcp_syncookies - BOOLEAN
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to use TCP extensions, can result in serious degradation
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of some services (f.e. SMTP relaying), visible not by you,
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but your clients and relays, contacting you. While you see
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- synflood warnings in logs not being really flooded, your server
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+ SYN flood warnings in logs not being really flooded, your server
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is seriously misconfigured.
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tcp_syn_retries - INTEGER
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@@ -419,19 +420,21 @@ tcp_window_scaling - BOOLEAN
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Enable window scaling as defined in RFC1323.
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tcp_wmem - vector of 3 INTEGERs: min, default, max
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- min: Amount of memory reserved for send buffers for TCP socket.
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+ min: Amount of memory reserved for send buffers for TCP sockets.
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Each TCP socket has rights to use it due to fact of its birth.
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Default: 4K
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- default: Amount of memory allowed for send buffers for TCP socket
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- by default. This value overrides net.core.wmem_default used
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- by other protocols, it is usually lower than net.core.wmem_default.
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+ default: initial size of send buffer used by TCP sockets. This
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+ value overrides net.core.wmem_default used by other protocols.
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+ It is usually lower than net.core.wmem_default.
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Default: 16K
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- max: Maximal amount of memory allowed for automatically selected
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- send buffers for TCP socket. This value does not override
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- net.core.wmem_max, "static" selection via SO_SNDBUF does not use this.
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- Default: 128K
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+ max: Maximal amount of memory allowed for automatically tuned
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+ send buffers for TCP sockets. This value does not override
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+ net.core.wmem_max. Calling setsockopt() with SO_SNDBUF disables
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+ automatic tuning of that socket's send buffer size, in which case
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+ this value is ignored.
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+ Default: between 64K and 4MB, depending on RAM size.
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tcp_workaround_signed_windows - BOOLEAN
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If set, assume no receipt of a window scaling option means the
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@@ -1060,24 +1063,193 @@ bridge-nf-filter-pppoe-tagged - BOOLEAN
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Default: 1
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-UNDOCUMENTED:
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+proc/sys/net/sctp/* Variables:
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+
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+addip_enable - BOOLEAN
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+ Enable or disable extension of Dynamic Address Reconfiguration
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+ (ADD-IP) functionality specified in RFC5061. This extension provides
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+ the ability to dynamically add and remove new addresses for the SCTP
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+ associations.
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+
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+ 1: Enable extension.
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+
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+ 0: Disable extension.
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+
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+ Default: 0
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+
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+addip_noauth_enable - BOOLEAN
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+ Dynamic Address Reconfiguration (ADD-IP) requires the use of
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+ authentication to protect the operations of adding or removing new
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+ addresses. This requirement is mandated so that unauthorized hosts
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+ would not be able to hijack associations. However, older
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+ implementations may not have implemented this requirement while
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+ allowing the ADD-IP extension. For reasons of interoperability,
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+ we provide this variable to control the enforcement of the
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+ authentication requirement.
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+
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+ 1: Allow ADD-IP extension to be used without authentication. This
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+ should only be set in a closed environment for interoperability
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+ with older implementations.
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+
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+ 0: Enforce the authentication requirement
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+
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+ Default: 0
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+
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+auth_enable - BOOLEAN
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+ Enable or disable Authenticated Chunks extension. This extension
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+ provides the ability to send and receive authenticated chunks and is
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+ required for secure operation of Dynamic Address Reconfiguration
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+ (ADD-IP) extension.
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+
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+ 1: Enable this extension.
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+ 0: Disable this extension.
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+
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+ Default: 0
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+
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+prsctp_enable - BOOLEAN
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+ Enable or disable the Partial Reliability extension (RFC3758) which
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+ is used to notify peers that a given DATA should no longer be expected.
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+
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+ 1: Enable extension
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+ 0: Disable
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+
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+ Default: 1
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+
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+max_burst - INTEGER
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+ The limit of the number of new packets that can be initially sent. It
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+ controls how bursty the generated traffic can be.
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+
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+ Default: 4
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+
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+association_max_retrans - INTEGER
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+ Set the maximum number for retransmissions that an association can
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+ attempt deciding that the remote end is unreachable. If this value
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+ is exceeded, the association is terminated.
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+
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+ Default: 10
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+
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+max_init_retransmits - INTEGER
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+ The maximum number of retransmissions of INIT and COOKIE-ECHO chunks
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+ that an association will attempt before declaring the destination
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+ unreachable and terminating.
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+
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+ Default: 8
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+
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+path_max_retrans - INTEGER
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+ The maximum number of retransmissions that will be attempted on a given
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+ path. Once this threshold is exceeded, the path is considered
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+ unreachable, and new traffic will use a different path when the
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+ association is multihomed.
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+
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+ Default: 5
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+
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+rto_initial - INTEGER
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+ The initial round trip timeout value in milliseconds that will be used
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+ in calculating round trip times. This is the initial time interval
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+ for retransmissions.
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+
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+ Default: 3000
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-dev_weight FIXME
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-discovery_slots FIXME
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-discovery_timeout FIXME
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-fast_poll_increase FIXME
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-ip6_queue_maxlen FIXME
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-lap_keepalive_time FIXME
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-lo_cong FIXME
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-max_baud_rate FIXME
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-max_dgram_qlen FIXME
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-max_noreply_time FIXME
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-max_tx_data_size FIXME
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-max_tx_window FIXME
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-min_tx_turn_time FIXME
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-mod_cong FIXME
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-no_cong FIXME
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-no_cong_thresh FIXME
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-slot_timeout FIXME
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-warn_noreply_time FIXME
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+rto_max - INTEGER
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+ The maximum value (in milliseconds) of the round trip timeout. This
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+ is the largest time interval that can elapse between retransmissions.
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+
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+ Default: 60000
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+
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+rto_min - INTEGER
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+ The minimum value (in milliseconds) of the round trip timeout. This
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+ is the smallest time interval the can elapse between retransmissions.
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+
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+ Default: 1000
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+
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+hb_interval - INTEGER
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+ The interval (in milliseconds) between HEARTBEAT chunks. These chunks
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+ are sent at the specified interval on idle paths to probe the state of
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+ a given path between 2 associations.
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+
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+ Default: 30000
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+
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+sack_timeout - INTEGER
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+ The amount of time (in milliseconds) that the implementation will wait
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+ to send a SACK.
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+
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+ Default: 200
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+
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+valid_cookie_life - INTEGER
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+ The default lifetime of the SCTP cookie (in milliseconds). The cookie
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+ is used during association establishment.
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+
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+ Default: 60000
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+
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+cookie_preserve_enable - BOOLEAN
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+ Enable or disable the ability to extend the lifetime of the SCTP cookie
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+ that is used during the establishment phase of SCTP association
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+
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+ 1: Enable cookie lifetime extension.
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+ 0: Disable
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+
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+ Default: 1
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+
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+rcvbuf_policy - INTEGER
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+ Determines if the receive buffer is attributed to the socket or to
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+ association. SCTP supports the capability to create multiple
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+ associations on a single socket. When using this capability, it is
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+ possible that a single stalled association that's buffering a lot
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+ of data may block other associations from delivering their data by
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+ consuming all of the receive buffer space. To work around this,
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+ the rcvbuf_policy could be set to attribute the receiver buffer space
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+ to each association instead of the socket. This prevents the described
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+ blocking.
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+
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+ 1: rcvbuf space is per association
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+ 0: recbuf space is per socket
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+
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+ Default: 0
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+
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+sndbuf_policy - INTEGER
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+ Similar to rcvbuf_policy above, this applies to send buffer space.
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+
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+ 1: Send buffer is tracked per association
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+ 0: Send buffer is tracked per socket.
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+
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+ Default: 0
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+
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+sctp_mem - vector of 3 INTEGERs: min, pressure, max
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+ Number of pages allowed for queueing by all SCTP sockets.
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+
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+ min: Below this number of pages SCTP is not bothered about its
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+ memory appetite. When amount of memory allocated by SCTP exceeds
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+ this number, SCTP starts to moderate memory usage.
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+
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+ pressure: This value was introduced to follow format of tcp_mem.
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+
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+ max: Number of pages allowed for queueing by all SCTP sockets.
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+
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+ Default is calculated at boot time from amount of available memory.
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+
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+sctp_rmem - vector of 3 INTEGERs: min, default, max
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+ See tcp_rmem for a description.
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+
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+sctp_wmem - vector of 3 INTEGERs: min, default, max
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+ See tcp_wmem for a description.
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+
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+UNDOCUMENTED:
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+/proc/sys/net/core/*
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+ dev_weight FIXME
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+
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+/proc/sys/net/unix/*
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+ max_dgram_qlen FIXME
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+
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+/proc/sys/net/irda/*
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+ fast_poll_increase FIXME
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+ warn_noreply_time FIXME
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+ discovery_slots FIXME
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+ slot_timeout FIXME
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+ max_baud_rate FIXME
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+ discovery_timeout FIXME
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+ lap_keepalive_time FIXME
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+ max_noreply_time FIXME
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+ max_tx_data_size FIXME
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+ max_tx_window FIXME
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+ min_tx_turn_time FIXME
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