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Documentation / networking / proc_net_tcp.txt




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Based on kernel version 3.13. Page generated on 2014-01-20 22:04 EST.

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