Net::Packet::TCP

Section: User Contributed Perl Documentation (3pm)
Updated: 2009-11-09
Index Return to Main Contents

NAME

Net::Packet::TCP - Transmission Control Protocol layer 4 object

SYNOPSIS

   use Net::Packet::Consts qw(:tcp);
   require Net::Packet::TCP;

   # Build a layer
   my $layer = Net::Packet::TCP->new(
      dst     => 22,
      options => "\x02\x04\x05\xb4", # MSS=1460
   );
   $layer->pack;

   print 'RAW: '.unpack('H*', $layer->raw)."\n";

   # Read a raw layer
   my $layer = Net::Packet::TCP->new(raw => $raw);

   print $layer->print."\n";
   print 'PAYLOAD: '.unpack('H*', $layer->payload)."\n"
      if $layer->payload;

DESCRIPTION

This modules implements the encoding and decoding of the TCP layer.

RFC: ftp://ftp.rfc-editor.org/in-notes/rfc793.txt

See also Net::Packet::Layer and Net::Packet::Layer4 for other attributes and methods.

ATTRIBUTES

src
dst: Source and destination ports.
flags: TCP flags, see CONSTANTS.
win: The window size.
seq
ack: Sequence and acknowledgment numbers.
off: The size in number of words of the TCP header.
x2: Reserved field.
checksum: The TCP header checksum.
urp: Urgent pointer.
options: TCP options, as a hexadecimal string.

METHODS

new

Object constructor. You can pass attributes that will overwrite default ones. Default values:

src: getRandomHighPort()

dst: 0

seq: getRandom32bitsInt()

ack: 0

x2: 0

off: 0

flags: NP_TCP_FLAG_SYN

win: 0xffff

checksum: 0

urp: 0

options: ""

recv

Will search for a matching replies in framesSorted or frames from a Net::Packet::Dump object.

pack

Packs all attributes into a raw format, in order to inject to network. Returns 1 on success, undef otherwise.

unpack

Unpacks raw data from network and stores attributes into the object. Returns 1 on success, undef otherwise.

getHeaderLength

Returns the header length in bytes, not including TCP options.

getOptionsLength

Returns options length in bytes.

haveFlagFin

haveFlagSyn

haveFlagRst

haveFlagPsh

haveFlagAck

haveFlagUrg

haveFlagEce

haveFlagCwr

Returns 1 if the specified TCP flag is set in flags attribute, 0 otherwise.

CONSTANTS

Load them: use Net::Packet::Consts qw(:tcp);

NP_TCP_FLAG_FIN
NP_TCP_FLAG_SYN
NP_TCP_FLAG_RST
NP_TCP_FLAG_PSH
NP_TCP_FLAG_ACK
NP_TCP_FLAG_URG
NP_TCP_FLAG_ECE
NP_TCP_FLAG_CWR: TCP flag constants.

AUTHOR

Patrice <GomoR> Auffret

COPYRIGHT AND LICENSE

You may distribute this module under the terms of the Artistic license. See LICENSE.Artistic file in the source distribution archive.

RELATED MODULES

NetPacket, Net::RawIP, Net::RawSock

This document was created by