59cb915c371312ef815793e6f8eb13a15e8c6707
[linux-2.6.git] / Documentation / networking / proc_net_tcp.txt
1 This document describes the interfaces /proc/net/tcp and /proc/net/tcp6.
2
3 These /proc interfaces provide information about currently active TCP 
4 connections, and are implemented by tcp_get_info() in net/ipv4/tcp_ipv4.c and
5 tcp6_get_info() in net/ipv6/tcp_ipv6.c, respectively.
6
7 It will first list all listening TCP sockets, and next list all established
8 TCP connections. A typical entry of /proc/net/tcp would look like this (split 
9 up into 3 parts because of the length of the line):
10
11    46: 010310AC:9C4C 030310AC:1770 01 
12    |      |      |      |      |   |--> connection state
13    |      |      |      |      |------> remote TCP port number
14    |      |      |      |-------------> remote IPv4 address
15    |      |      |--------------------> local TCP port number
16    |      |---------------------------> local IPv4 address
17    |----------------------------------> number of entry
18
19    00000150:00000000 01:00000019 00000000  
20       |        |     |     |       |--> number of unrecovered RTO timeouts
21       |        |     |     |----------> number of jiffies until timer expires
22       |        |     |----------------> timer_active (see below)
23       |        |----------------------> receive-queue
24       |-------------------------------> transmit-queue
25
26    1000        0 54165785 4 cd1e6040 25 4 27 3 -1
27     |          |    |     |    |     |  | |  | |--> slow start size threshold, 
28     |          |    |     |    |     |  | |  |      or -1 if the treshold
29     |          |    |     |    |     |  | |  |      is >= 0xFFFF
30     |          |    |     |    |     |  | |  |----> sending congestion window
31     |          |    |     |    |     |  | |-------> (ack.quick<<1)|ack.pingpong
32     |          |    |     |    |     |  |---------> Predicted tick of soft clock
33     |          |    |     |    |     |              (delayed ACK control data)
34     |          |    |     |    |     |------------> retransmit timeout
35     |          |    |     |    |------------------> location of socket in memory
36     |          |    |     |-----------------------> socket reference count
37     |          |    |-----------------------------> inode
38     |          |----------------------------------> unanswered 0-window probes
39     |---------------------------------------------> uid
40
41 timer_active:
42   0  no timer is pending
43   1  retransmit-timer is pending
44   2  another timer (e.g. delayed ack or keepalive) is pending
45   3  this is a socket in TIME_WAIT state. Not all fields will contain 
46      data (or even exist)
47   4  zero window probe timer is pending