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