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