NAME
Net::SnoopLog - Read snoop network packet logs, from RFC1761
snoop ver 2. Perl implementation (not an interface).
SYNOPSIS
use Net::SnoopLog;
$log = Net::SnoopLog->new();
$log->read("/tmp/out01");
@Indexes = $log->indexes;
foreach $index (@Indexes) {
($length_orig,$length_incl,$drops,$secs,$msecs) =
$log->header($index);
$data = $log->data($index);
# your code here
}
DESCRIPTION
This module can read the data and headers from snoop ver 2
logs (those that obey RFC1761 - try "man snoop").
METHODS
new ()
Constructor, return a SnoopLog object.
read (FILENAME)
Read the snoop file indicated into memory.
indexes ()
Return an array of index numbers for the packet loaded
from the snoop file. The indexes start at 0.
maxindex ()
Return the number of the last index. More memory
efficient than indexes(). Add 1 to get the packet count.
The indexes start at 0.
header (INDEX)
Takes an integer index number and returns the packet
header. This is:
Length of original packet,
Length actually included in the snoop log,
Cumulative drops (since the snoop log began),
Packet arrival time as seconds since Jan 1st 1970,
Microseconds
data (INDEX)
Takes an integer index number and returns the raw packet
data. (This is usually Ethernet/IP/TCP data).
version ()
Returns a string containing the numeric snoop log
version, which is expected to be "2".
datalink ()
Returns a strings containing the numeric datalink type,
see RFC 1761 for a table of these. (4 is Ethernet).
INSTALLATION
perl Makefile.PL
make
make test
make install
DEPENDENCIES
ExtUtils::MakeMaker
EXAMPLES
Once you can read the raw packet data, the next step is read
through the protocol stack. An Ethernet/802.3 example is,
($ether_dest,$ether_src,$ether_type,$ether_data) =
unpack('H12H12H4a*',$data);
Keep an eye on CPAN for Ethernet, IP and TCP modules.
LIMITATIONS
This reads snoop version 2 logs (the most common). There
could be a new version in the distant future with a move to
64-bit timestamps - at which point this module will need
updating.
TODO
Future versions should include the ability to write as well
as read snoop logs. Also a memory efficient technique to
process very large snoop logs (where the log size is greater
than available virtual memory).
SEE ALSO
RFC 1761
COPYRIGHT
Copyright (c) 2003 Brendan Gregg. All rights reserved. This
library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
AUTHORS
Brendan Gregg <brendan.gregg@tpg.com.au> [Sydney, Australia]