1*83261901SMauro Carvalho Chehab.. SPDX-License-Identifier: GPL-2.0 2*83261901SMauro Carvalho Chehab 3*83261901SMauro Carvalho Chehab============================================ 4*83261901SMauro Carvalho ChehabThe proc/net/tcp and proc/net/tcp6 variables 5*83261901SMauro Carvalho Chehab============================================ 6*83261901SMauro Carvalho Chehab 7*83261901SMauro Carvalho ChehabThis document describes the interfaces /proc/net/tcp and /proc/net/tcp6. 8*83261901SMauro Carvalho ChehabNote that these interfaces are deprecated in favor of tcp_diag. 9*83261901SMauro Carvalho Chehab 10*83261901SMauro Carvalho ChehabThese /proc interfaces provide information about currently active TCP 11*83261901SMauro Carvalho Chehabconnections, and are implemented by tcp4_seq_show() in net/ipv4/tcp_ipv4.c 12*83261901SMauro Carvalho Chehaband tcp6_seq_show() in net/ipv6/tcp_ipv6.c, respectively. 13*83261901SMauro Carvalho Chehab 14*83261901SMauro Carvalho ChehabIt will first list all listening TCP sockets, and next list all established 15*83261901SMauro Carvalho ChehabTCP connections. A typical entry of /proc/net/tcp would look like this (split 16*83261901SMauro Carvalho Chehabup into 3 parts because of the length of the line):: 17*83261901SMauro Carvalho Chehab 18*83261901SMauro Carvalho Chehab 46: 010310AC:9C4C 030310AC:1770 01 19*83261901SMauro Carvalho Chehab | | | | | |--> connection state 20*83261901SMauro Carvalho Chehab | | | | |------> remote TCP port number 21*83261901SMauro Carvalho Chehab | | | |-------------> remote IPv4 address 22*83261901SMauro Carvalho Chehab | | |--------------------> local TCP port number 23*83261901SMauro Carvalho Chehab | |---------------------------> local IPv4 address 24*83261901SMauro Carvalho Chehab |----------------------------------> number of entry 25*83261901SMauro Carvalho Chehab 26*83261901SMauro Carvalho Chehab 00000150:00000000 01:00000019 00000000 27*83261901SMauro Carvalho Chehab | | | | |--> number of unrecovered RTO timeouts 28*83261901SMauro Carvalho Chehab | | | |----------> number of jiffies until timer expires 29*83261901SMauro Carvalho Chehab | | |----------------> timer_active (see below) 30*83261901SMauro Carvalho Chehab | |----------------------> receive-queue 31*83261901SMauro Carvalho Chehab |-------------------------------> transmit-queue 32*83261901SMauro Carvalho Chehab 33*83261901SMauro Carvalho Chehab 1000 0 54165785 4 cd1e6040 25 4 27 3 -1 34*83261901SMauro Carvalho Chehab | | | | | | | | | |--> slow start size threshold, 35*83261901SMauro Carvalho Chehab | | | | | | | | | or -1 if the threshold 36*83261901SMauro Carvalho Chehab | | | | | | | | | is >= 0xFFFF 37*83261901SMauro Carvalho Chehab | | | | | | | | |----> sending congestion window 38*83261901SMauro Carvalho Chehab | | | | | | | |-------> (ack.quick<<1)|ack.pingpong 39*83261901SMauro Carvalho Chehab | | | | | | |---------> Predicted tick of soft clock 40*83261901SMauro Carvalho Chehab | | | | | | (delayed ACK control data) 41*83261901SMauro Carvalho Chehab | | | | | |------------> retransmit timeout 42*83261901SMauro Carvalho Chehab | | | | |------------------> location of socket in memory 43*83261901SMauro Carvalho Chehab | | | |-----------------------> socket reference count 44*83261901SMauro Carvalho Chehab | | |-----------------------------> inode 45*83261901SMauro Carvalho Chehab | |----------------------------------> unanswered 0-window probes 46*83261901SMauro Carvalho Chehab |---------------------------------------------> uid 47*83261901SMauro Carvalho Chehab 48*83261901SMauro Carvalho Chehabtimer_active: 49*83261901SMauro Carvalho Chehab 50*83261901SMauro Carvalho Chehab == ================================================================ 51*83261901SMauro Carvalho Chehab 0 no timer is pending 52*83261901SMauro Carvalho Chehab 1 retransmit-timer is pending 53*83261901SMauro Carvalho Chehab 2 another timer (e.g. delayed ack or keepalive) is pending 54*83261901SMauro Carvalho Chehab 3 this is a socket in TIME_WAIT state. Not all fields will contain 55*83261901SMauro Carvalho Chehab data (or even exist) 56*83261901SMauro Carvalho Chehab 4 zero window probe timer is pending 57*83261901SMauro Carvalho Chehab == ================================================================ 58