Linux::Proc::Net::TCP - Parser for Linux /proc/net/tcp and /proc/net/tcp6
use Linux::Proc::Net::TCP;
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 );
}
This module can read and parse the information available from /proc/net/tcp in Linux systems.
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:
disables parsing of the file /proc/net/tcp containing state information for TCP over IP4 connections
disables parsing of the file /proc/net/tcp6 containing state information for TCP over IP6 connections
allows to override the default mount point for the procfs at /proc
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;
}
returns the list of TCP ports where there are some service listening.
This method can be used to find some unallocated 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 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
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
Salvador Fandiño <sfandino@yahoo.com>
Copyright (C) 2010, 2012 by Qindel Formacion 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.
