[net-next-2.6.git] / Documentation / networking / proc_net_tcp.txt

This document describes the interfaces /proc/net/tcp and /proc/net/tcp6.
Note that these interfaces are deprecated in favor of tcp_diag.

These /proc interfaces provide information about currently active TCP 
connections, and are implemented by tcp4_seq_show() in net/ipv4/tcp_ipv4.c
and tcp6_seq_show() in net/ipv6/tcp_ipv6.c, respectively.

It will first list all listening TCP sockets, and next list all established
TCP connections. A typical entry of /proc/net/tcp would look like this (split 
up into 3 parts because of the length of the line):

   46: 010310AC:9C4C 030310AC:1770 01 
   |      |      |      |      |   |--> connection state
   |      |      |      |      |------> remote TCP port number
   |      |      |      |-------------> remote IPv4 address
   |      |      |--------------------> local TCP port number
   |      |---------------------------> local IPv4 address
   |----------------------------------> number of entry

   00000150:00000000 01:00000019 00000000  
      |        |     |     |       |--> number of unrecovered RTO timeouts
      |        |     |     |----------> number of jiffies until timer expires
      |        |     |----------------> timer_active (see below)
      |        |----------------------> receive-queue
      |-------------------------------> transmit-queue

   1000        0 54165785 4 cd1e6040 25 4 27 3 -1
    |          |    |     |    |     |  | |  | |--> slow start size threshold, 
    |          |    |     |    |     |  | |  |      or -1 if the threshold
    |          |    |     |    |     |  | |  |      is >= 0xFFFF
    |          |    |     |    |     |  | |  |----> sending congestion window
    |          |    |     |    |     |  | |-------> (ack.quick<<1)|ack.pingpong
    |          |    |     |    |     |  |---------> Predicted tick of soft clock
    |          |    |     |    |     |              (delayed ACK control data)
    |          |    |     |    |     |------------> retransmit timeout
    |          |    |     |    |------------------> location of socket in memory
    |          |    |     |-----------------------> socket reference count
    |          |    |-----------------------------> inode
    |          |----------------------------------> unanswered 0-window probes
    |---------------------------------------------> uid

timer_active:
  0  no timer is pending
  1  retransmit-timer is pending
  2  another timer (e.g. delayed ack or keepalive) is pending
  3  this is a socket in TIME_WAIT state. Not all fields will contain 
     data (or even exist)
  4  zero window probe timer is pending
Commit	Line	Data
1da177e4	1	This document describes the interfaces /proc/net/tcp and /proc/net/tcp6.
d603d0ab	2	Note that these interfaces are deprecated in favor of tcp_diag.
1da177e4 LT	3
1da177e4 LT	4	These /proc interfaces provide information about currently active TCP
d603d0ab JD	5	connections, and are implemented by tcp4_seq_show() in net/ipv4/tcp_ipv4.c
d603d0ab JD	6	and tcp6_seq_show() in net/ipv6/tcp_ipv6.c, respectively.
1da177e4 LT	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,
fa00e7e1	29	\| \| \| \| \| \| \| \| \| or -1 if the threshold
1da177e4 LT	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