NAME
Parse::Snort - Parse and create Snort rules
VERSION
Version 0.05
SYNOPSIS
use Parse::Snort;
my $rule = Parse::Snort->new(
action => 'alert',
proto => 'tcp',
src => '$HOME_NET', src_port => 'any',
direction => '->'
dst =>'$EXTERNAL_NET', dst_port => 'any'
);
$rule->action("pass");
$rule->opts(
[ 'depth' => 50 ],
[ 'offset' => 0 ],
[ 'content' => "perl6" ],
[ "nocase" ]
);
my $rule = Parse::Snort->new();
$rule->parse('pass tcp $HOME_NET any -> $EXTERNAL_NET 6667;');
$rule->msg("IRC server");
my $rule_string = $rule->as_string;
);
METHODS
These are the object methods that can be used to read or modify any part of a Snort rule. Please note: None of these methods provide any sort of input validation to make sure that the rule makes sense, or can be parsed at all by Snort.
new ()
Create a new "Parse::Snort" object, and return it. There are a
couple of options when creating the object:
new ( )
Create an unpopulated object, that can be filled in using the
individual rule element methods, or can be populated with the
parse method.
new ( $rule_string )
Create an object based on a plain text Snort rule, all on one
line. This module doesn't understand the UNIX style line
continuations (a backslash at the end of the line) that Snort
does.
$rule_string = 'alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"perl 6 download detected\; may the world rejoice!";depth:150; offset:0; content:"perl-6.0.0"; nocase;)'
new ( $rule_element_hashref )
Create an object baesd on a prepared hash reference similar to
the internal strucutre of the Parse::Snort object.
$rule_element_hashref = {
action => 'alert',
proto => 'tcp',
src => '$EXTERNAL_NET', src_port => 'any',
direction => '->',
dst => '$HOME_NET', dst_port => 'any',
opts => [
[ 'msg' => '"perl 6 download detected\; may the world rejoice!"' ],
[ 'depth' => 150 ],
[ 'offset' => 0 ].
[ 'content' => 'perl-6.0.0' ],
[ 'nocase' ],
],
};
parse( $rule_string )
The parse method is what interprets a plain text rule, and populates
the rule object. Beacuse this module does not support the UNIX style
line-continuations (backslash at the end of a line) the rule must be
all on one line, otherwise the parse will fail in unpredictably
interesting and confusing ways. The parse method tries to interpret
the rule from left to right, calling the individual accessor methods
for each rule element. This will overwrite the contents of the
object (if any), so if you want to parse multiple rules at once, you
will need multiple objects.
$rule->parse($rule_string);
METHODS FOR ACCESSING RULE ELEMENTS
You can access the core parts of a rule (action, protocol, source IP,
etc) with the method of their name. These are read/write Class::Accessor
accessors. If you want to read the value, don't pass an argument. If you
want to set the value, pass in the new value. In either case it returns
the current value, or undef if the value has not been set yet.
action
The rule action. Generally one of the following: "alert", "pass",
"drop", "sdrop", or "log".
proto
The protocol of the rule. Generally one of the following: "tcp",
"udp", "ip", or "icmp".
src The source IP address for the rule. Generally a dotted decimal IP
address, Snort $HOME_NET variable, or CIDR block notation.
src_port
The source port for the rule. Generally a static port, or a
contigious range of ports.
direction
The direction of the rule. One of the following: "-"> "<"> or "<-".
dst The destination IP address for the rule. Same format as "src"
dst_port
The destination port for the rule. Same format as "src"
opts ( $opts_array_ref )
opts ( $opts_string )
The opts method can be used to read existing options of a parsed
rule, or set them. The method takes two forms of arguments, either
an Array of Arrays, or a rule string.
$opts_array_ref
$opts_array_ref = [
[ 'msg' => '"perl 6 download detected\; may the world rejoice!"' ],
[ 'depth' => 150 ],
[ 'offset' => 0 ].
[ 'content' => 'perl-6.0.0' ],
[ 'nocase' ],
]
$opts_string
$opts_string='(msg:"perl 6 download detected\; may the world rejoice!";depth:150; offset:0; content:"perl-6.0.0"; nocase;)';
The parenthesis surround the series of "key:value;" pairs are
optional.
HELPER METHODS FOR VARIOUS OPTIONS
sid
rev
msg
classtype
gid
metadata
priority
The these methods allow direct access to the rule option of the same
name
my $sid = $rule_obj->sid(); # reads the sid of the rule
$rule_obj->sid($sid); # sets the sid of the rule
... etc ...
references
The "references" method permits read-only access to the "reference:"
options in the rule. This is in the form of an array of arrays, with
each reference in the format
[ 'reference_type' => 'reference_value' ]
To modify references, use the "opts" method to grab all the rule
options, modify it to your needs, and use the "opts" method to save
your changes back to the rule object.
$references = $rule->references(); # just the references
$no_references = grep { $_->[0] != "reference" } @{ $rule->opts() }; # everything but the references
as_string
The "as_string" method returns a string that matches the normal
Snort rule form of the object. This is what you want to use to write
a rule to an output file that will be read by Snort.
AUTHOR
Richard G Harman Jr, "<perl-cpan at richardharman.com>"
BUGS
Please report any bugs or feature requests to "bug-parse-snort at rt.cpan.org", or through the web interface at <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Parse-Snort>. I will be notified, and then you' ll automatically be notified of progress on your bug as I make changes.
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc Parse::Snort
You can also look for information at:
DEPENDENCIES
Test::More, Class::Accessor, List::Util
ACKNOWLEDGEMENTS
MagNET #perl for putting up with me :)
COPYRIGHT & LICENSE
Copyright 2007 Richard Harman, all rights reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.