NAME
Linux::Proc::Net::TCP - Parser for Linux /proc/net/tcp and /proc/net/tcp6
SYNOPSIS
my
$table
= Linux::Proc::Net::TCP->
read
;
for
my
$entry
(
@$table
) {
printf
(
"%s:%d --> %s:%d, %s\n"
,
$entry
->local_address,
$entry
->local_port,
$entry
->rem_address,
$entry
->rem_port,
$entry
->st );
}
DESCRIPTION
This module can read and parse the information available from /proc/net/tcp in Linux systems.
API
The table object
- $table = Linux::Proc::Net::TCP->read
- $table = Linux::Proc::Net::TCP->read(%opts)
-
reads
/proc/net/tcp
and/proc/net/tcp6
and returns an object representing a table of the connections.Individual entries in the table can be accessed just dereferencing the returned object. For instance:
for
my
$entry
(
@$table
) {
# do something with $entry
}
The table entries are of class
Linux::Proc::Net::TCP::Entry
described below.This method accepts the following optional arguments:
- ip4 => 0
-
disables parsing of the file /proc/net/tcp containing state information for TCP over IP4 connections
- ip6 => 0
-
disables parsing of the file /proc/net/tcp6 containing state information for TCP over IP6 connections
- mnt => $procfs_mount_point
-
overrides the default mount point for the procfs at
/proc
.
- $table->listeners
-
returns a list of the entries that are listeners:
for
my
$entry
(
$table
->listeners) {
printf
"listener: %s:%d\n"
,
$entry
->local_address,
$entry
->local_port;
}
- $table->listener_ports
-
returns the list of TCP ports where there are some service listening.
This method can be used to find some unused port:
my
@used_ports
= Linux::Proc::Net::TCP->
read
->listener_ports;
my
%used_port
=
map
{
$_
=> 1 }
@used_ports
;
my
$port
=
$start
;
$port
++
while
$used_port
{
$port
};
The entry object
The entries in the table are of class Linux::Proc::Net::TCP::Entry
and implement the following read only accessors:
sl local_address local_port rem_address rem_port st tx_queue
rx_queue timer tm_when retrnsmt uid timeout inode reference_count
memory_address retransmit_timeout predicted_tick ack_quick
ack_pingpong sending_congestion_window slow_start_size_threshold
ip4 ip6
The /proc/net/tcp documentation
This is the documentation about /proc/net/tcp available from the Linux kernel source distribution:
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
AUTHOR
Salvador Fandiño <sfandino@yahoo.com>
COPYRIGHT AND LICENSE
Copyright (C) 2010, 2012, 2014 by Qindel Formación y Servicios S.L.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.10.1 or, at your option, any later version of Perl 5 you may have available.