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Viewing changes to Documentation/networking/proc_net_tcp.txt

  • Committer: Bazaar Package Importer
  • Author(s): Mathieu Poirier
  • Date: 2011-02-18 09:43:31 UTC
  • Revision ID: james.westby@ubuntu.com-20110218094331-eyubsja4f9k0yhmq
Tags: 2.6.35-1.1
Initial release.

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Documentation/networking/proc_net_tcp.txt
 
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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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  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