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Diffstat (limited to 'Documentation/networking/proc_net_tcp.rst')
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diff --git a/Documentation/networking/proc_net_tcp.rst b/Documentation/networking/proc_net_tcp.rst new file mode 100644 index 000000000..7d9dfe36a --- /dev/null +++ b/Documentation/networking/proc_net_tcp.rst @@ -0,0 +1,57 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================================ +The proc/net/tcp and proc/net/tcp6 variables +============================================ + +This document describes the interfaces /proc/net/tcp and /proc/net/tcp6. +Note that these interfaces are deprecated in favor of tcp_diag. + +These /proc interfaces provide information about currently active TCP +connections, and are implemented by tcp4_seq_show() in net/ipv4/tcp_ipv4.c +and tcp6_seq_show() in net/ipv6/tcp_ipv6.c, respectively. + +It will first list all listening TCP sockets, and next list all established +TCP connections. A typical entry of /proc/net/tcp would look like this (split +up into 3 parts because of the length of the line):: + + 46: 010310AC:9C4C 030310AC:1770 01 + | | | | | |--> connection state + | | | | |------> remote TCP port number + | | | |-------------> remote IPv4 address + | | |--------------------> local TCP port number + | |---------------------------> local IPv4 address + |----------------------------------> number of entry + + 00000150:00000000 01:00000019 00000000 + | | | | |--> number of unrecovered RTO timeouts + | | | |----------> number of jiffies until timer expires + | | |----------------> timer_active (see below) + | |----------------------> receive-queue + |-------------------------------> transmit-queue + + 1000 0 54165785 4 cd1e6040 25 4 27 3 -1 + | | | | | | | | | |--> slow start size threshold, + | | | | | | | | | or -1 if the threshold + | | | | | | | | | is >= 0xFFFF + | | | | | | | | |----> sending congestion window + | | | | | | | |-------> (ack.quick<<1)|ack.pingpong + | | | | | | |---------> Predicted tick of soft clock + | | | | | | (delayed ACK control data) + | | | | | |------------> retransmit timeout + | | | | |------------------> location of socket in memory + | | | |-----------------------> socket reference count + | | |-----------------------------> inode + | |----------------------------------> unanswered 0-window probes + |---------------------------------------------> uid + +timer_active: + + == ================================================================ + 0 no timer is pending + 1 retransmit-timer is pending + 2 another timer (e.g. delayed ack or keepalive) is pending + 3 this is a socket in TIME_WAIT state. Not all fields will contain + data (or even exist) + 4 zero window probe timer is pending + == ================================================================ |