1*4882a593Smuzhiyun.. SPDX-License-Identifier: GPL-2.0 2*4882a593Smuzhiyun 3*4882a593Smuzhiyun============================================ 4*4882a593SmuzhiyunThe proc/net/tcp and proc/net/tcp6 variables 5*4882a593Smuzhiyun============================================ 6*4882a593Smuzhiyun 7*4882a593SmuzhiyunThis document describes the interfaces /proc/net/tcp and /proc/net/tcp6. 8*4882a593SmuzhiyunNote that these interfaces are deprecated in favor of tcp_diag. 9*4882a593Smuzhiyun 10*4882a593SmuzhiyunThese /proc interfaces provide information about currently active TCP 11*4882a593Smuzhiyunconnections, and are implemented by tcp4_seq_show() in net/ipv4/tcp_ipv4.c 12*4882a593Smuzhiyunand tcp6_seq_show() in net/ipv6/tcp_ipv6.c, respectively. 13*4882a593Smuzhiyun 14*4882a593SmuzhiyunIt will first list all listening TCP sockets, and next list all established 15*4882a593SmuzhiyunTCP connections. A typical entry of /proc/net/tcp would look like this (split 16*4882a593Smuzhiyunup into 3 parts because of the length of the line):: 17*4882a593Smuzhiyun 18*4882a593Smuzhiyun 46: 010310AC:9C4C 030310AC:1770 01 19*4882a593Smuzhiyun | | | | | |--> connection state 20*4882a593Smuzhiyun | | | | |------> remote TCP port number 21*4882a593Smuzhiyun | | | |-------------> remote IPv4 address 22*4882a593Smuzhiyun | | |--------------------> local TCP port number 23*4882a593Smuzhiyun | |---------------------------> local IPv4 address 24*4882a593Smuzhiyun |----------------------------------> number of entry 25*4882a593Smuzhiyun 26*4882a593Smuzhiyun 00000150:00000000 01:00000019 00000000 27*4882a593Smuzhiyun | | | | |--> number of unrecovered RTO timeouts 28*4882a593Smuzhiyun | | | |----------> number of jiffies until timer expires 29*4882a593Smuzhiyun | | |----------------> timer_active (see below) 30*4882a593Smuzhiyun | |----------------------> receive-queue 31*4882a593Smuzhiyun |-------------------------------> transmit-queue 32*4882a593Smuzhiyun 33*4882a593Smuzhiyun 1000 0 54165785 4 cd1e6040 25 4 27 3 -1 34*4882a593Smuzhiyun | | | | | | | | | |--> slow start size threshold, 35*4882a593Smuzhiyun | | | | | | | | | or -1 if the threshold 36*4882a593Smuzhiyun | | | | | | | | | is >= 0xFFFF 37*4882a593Smuzhiyun | | | | | | | | |----> sending congestion window 38*4882a593Smuzhiyun | | | | | | | |-------> (ack.quick<<1)|ack.pingpong 39*4882a593Smuzhiyun | | | | | | |---------> Predicted tick of soft clock 40*4882a593Smuzhiyun | | | | | | (delayed ACK control data) 41*4882a593Smuzhiyun | | | | | |------------> retransmit timeout 42*4882a593Smuzhiyun | | | | |------------------> location of socket in memory 43*4882a593Smuzhiyun | | | |-----------------------> socket reference count 44*4882a593Smuzhiyun | | |-----------------------------> inode 45*4882a593Smuzhiyun | |----------------------------------> unanswered 0-window probes 46*4882a593Smuzhiyun |---------------------------------------------> uid 47*4882a593Smuzhiyun 48*4882a593Smuzhiyuntimer_active: 49*4882a593Smuzhiyun 50*4882a593Smuzhiyun == ================================================================ 51*4882a593Smuzhiyun 0 no timer is pending 52*4882a593Smuzhiyun 1 retransmit-timer is pending 53*4882a593Smuzhiyun 2 another timer (e.g. delayed ack or keepalive) is pending 54*4882a593Smuzhiyun 3 this is a socket in TIME_WAIT state. Not all fields will contain 55*4882a593Smuzhiyun data (or even exist) 56*4882a593Smuzhiyun 4 zero window probe timer is pending 57*4882a593Smuzhiyun == ================================================================ 58