NAME

Snort::Rule - Perl extension for dynamically building snort rules

SYNOPSIS

  use Snort::Rule;
  $rule = Snort::Rule->new(
        -action => 'alert',
        -proto  => 'tcp',
        -src    => 'any',
        -sport  => 'any',
        -dir    => '->',
        -dst    => '192.188.1.1',
        -dport  => '44444',
  );

  $rule->opts('msg','Test Rule"');
  $rule->opts('threshold','type limit,track by_src,count 1,seconds 3600');
  $rule->opts('sid','500000');

  print $rule->string()."\n";

  OR

  $rule = 'alert tcp $SMTP_SERVERS any -> $EXTERNAL_NET 25 (msg:"BLEEDING-EDGE POLICY SMTP US Top Secret PROPIN"; flow:to_server,established; content:"Subject|3A|"; pcre:"/(TOP\sSECRET|TS)//[\s\w,/-]*PROPIN[\s\w,/-]*(?=//(25)?X[1-9])/ism"; classtype:policy-violation; sid:2002448; rev:1;)';

  $rule = Snort::Rule->new(-parse => $rule);
  print $rule->string()."\n";

DESCRIPTION

This is a very simple snort rule object. It was developed to allow for scripted dynamic rule creation. Ideally you could dynamically take a list of bad hosts and build an array of snort rule objects from that list. Then write that list using the string() method to a snort rules file.

OBJECT METHODS

new

Reads in the initial headers to generate a rule and constructs the snort::rule object around it.

Accepts:

  -action => [string] ? [alert|log|pass|...] : 'alert'
  -proto => [string] ? [ip|udp|tcp|...] : 'IP'
  -src => [string] ? [$strIp] : 'any'
  -sport => [int] ? [$sport] : 'any'
  -dir => [string] ? [->|<-|<>] : '->'
  -dst => [string] ? [$strIp] : 'any'
  -dport => [int] ? [$dport] : 'any'
  -opts => [hashref] ? [hashref] : '';

  -parse => $strRule # for parsing an existing rule into the object

Returns: OBJECTREF

string

Outputs the rule in string form.

  print $sr->string()."\n";

Prints "options only" string:

  print $sr->string(-optionsOnly => 1)."\n";

action

Sets and returns the rule action [alert,log,pass,...]

  $rule->action('alert');

proto

Sets and returns the protocol used in the rule [tcp,icmp,udp]

  $rule->proto('tcp');

src

Sets and returns the source used in the rule. Make sure you use SINGLE QUOTES for variables!!!

  $rule->src('$EXTERNAL_NET');

sport

Sets and returns the source port used in the rule

  $rule->sport(80);

dir

Sets and returns the direction operator used in the rule, -> <- or <>

  $rule->dir('->');

dst

Sets and returns the destination used in the rule

  $rule->dst('$HOME_NET');
  $rule->dst('192.168.1.1');

dport

Sets and returns the destination port used in the rule

  $rule->dport(6667);

opts

Sets an option and a value used in the rule. This currently can only be done one set at a time, and is printed in the order it was set.

  $rule->opts(option,value);
  $rule->opts('msg','this is a test rule');

This will return a hashref: $hashref->{$keyOrderValue}->{option} and $hashref->{$keyOrderValue}->{value}

  my $hashref = $rule->opts();

There is a fixQuotes() function that reads through this information before setting it, just to ensure the right options are sane. It's a very very basic function, but it seems to get the job done.

This method will also accept HASHREF's for easier use:

  $rule->opts({
        msg     => 'test1',
        rev     => '222',
        content => 'Subject|3A|',
        nocase => '',
  });

  By passing an option => '', the parser will set its value to "''". When $self->string() is called, the option will be written as: option;
  ex: nocase => '', will result in an option output of: ...., nocase; ...

opt

Gets the value of the first option with a given name.

  $rule->opt(option);
  print $rule->opt('sid') . ': ' . $rule->opt('msg');

AUTHOR

Wes Young, <saxguard9-cpan@yahoo.com>

COPYRIGHT AND LICENSE

Copyright (C) 2006 by Wes Young

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.6 or, at your option, any later version of Perl 5 you may have available.

cpanm Snort::Rule

perl -MCPAN -e shell
install Snort::Rule