Hi,
I prepared this little documentation (the patch adds it to
/Documentation/networking). I think it applies to both the 2.4 and 2.6
trees.
Please consider it for inclusion.
Kind regards,
--
Arnout Engelen <arnouten@bzzt.net>
"If it sounds good, it /is/ good."
-- Duke Ellington
This document describes the interfaces /proc/net/tcp and /proc/net/tcp6.
These /proc interfaces provide information about currently active TCP
connections, and are implemented by tcp_get_info() in net/ipv4/tcp_ipv4.c and
tcp6_get_info() 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 treshold
| | | | | | | | | 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
diff -Naur linux-2.6.9-clean/Documentation/networking/proc_net_tcp.txt linux-2.6.9/Documentation/networking/proc_net_tcp.txt
--- linux-2.6.9-clean/Documentation/networking/proc_net_tcp.txt 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.9/Documentation/networking/proc_net_tcp.txt 2004-10-20 14:48:45.000000000 +0200
@@ -0,0 +1,47 @@
+This document describes the interfaces /proc/net/tcp and /proc/net/tcp6.
+
+These /proc interfaces provide information about currently active TCP
+connections, and are implemented by tcp_get_info() in net/ipv4/tcp_ipv4.c and
+tcp6_get_info() 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 treshold
+ | | | | | | | | | 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
