shorewall_code/Shorewall-perl/Shorewall/Actions.pm

#
# Shorewall-perl 4.1 -- /usr/share/shorewall-perl/Shorewall/Actions.pm
#
#     This program is under GPL [http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt]
#
#     (c) 2007 - Tom Eastep (teastep@shorewall.net)
#
#       Complete documentation is available at http://shorewall.net
#
#       This program is free software; you can redistribute it and/or modify
#       it under the terms of Version 2 of the GNU General Public License
#       as published by the Free Software Foundation.
#
#       This program is distributed in the hope that it will be useful,
#       but WITHOUT ANY WARRANTY; without even the implied warranty of
#       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
#       GNU General Public License for more details.
#
#       You should have received a copy of the GNU General Public License
#       along with this program; if not, write to the Free Software
#       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
#   This module contains the code for dealing with actions (built-in,
#   standard and user-defined) and Macros.
#
package Shorewall::Actions;
require Exporter;
use Shorewall::Config qw(:DEFAULT :internal);
use Shorewall::Zones;
use Shorewall::Chains qw(:DEFAULT :internal);

use strict;

our @ISA = qw(Exporter);
our @EXPORT = qw( merge_levels
		  isolate_basic_target
		  get_target_param
		  add_requiredby
		  createactionchain
		  find_logactionchain
		  process_actions1
		  process_actions2
		  process_actions3

		  find_macro
		  split_action
		  substitute_param
		  merge_macro_source_dest
		  merge_macro_column

		  %usedactions
		  %default_actions
		  %actions

		  %macros
		  );
our @EXPORT_OK = qw( initialize );
our $VERSION = 4.1.1;

#
#  Used Actions. Each action that is actually used has an entry with value 1.
#
our %usedactions;
#
# Default actions for each policy.
#
our %default_actions;

#  Action Table
#
#     %actions{ <action1> =>  { requires => { <requisite1> = 1,
#                                             <requisite2> = 1,
#                                             ...
#                                           } ,
#                               actchain => <action chain number> # Used for generating unique chain names for each <level>:<tag> pair.
#
our %actions;
#
# Contains an entry for each used <action>:<level>[:<tag>] that maps to the associated chain.
#
our %logactionchains;

our %macros;

#
# Initialize globals -- we take this novel approach to globals initialization to allow
#                       the compiler to run multiple times in the same process. The
#                       initialize() function does globals initialization for this
#                       module and is called from an INIT block below. The function is
#                       also called by Shorewall::Compiler::compiler at the beginning of
#                       the second and subsequent calls to that function.
#

sub initialize() {
    %usedactions     = ();
    %default_actions = ( DROP     => 'none' ,
			 REJECT   => 'none' ,
			 ACCEPT   => 'none' ,
			 QUEUE    => 'none' );
    %actions         = ();
    %logactionchains = ();
}

INIT {
    initialize;
}

#
# This function determines the logging for a subordinate action or a rule within a superior action
#
sub merge_levels ($$) {
    my ( $superior, $subordinate ) = @_;

    my @supparts = split /:/, $superior;
    my @subparts = split /:/, $subordinate;

    my $subparts = @subparts;

    my $target   = $subparts[0];

    push @subparts, '' while @subparts < 3;   #Avoid undefined values

    my $level = $supparts[1];
    my $tag   = $supparts[2];

    if ( @supparts == 3 ) {
	return "$target:none!:$tag"   if $level eq 'none!';
	return "$target:$level:$tag"  if $level =~ /!$/;
	return $subordinate           if $subparts >= 2;
	return "$target:$level:$tag";
    }

    if ( @supparts == 2 ) {
	return "$target:none!"        if $level eq 'none!';
	return "$target:$level"       if ($level =~ /!$/) || ($subparts < 2);
    }

    $subordinate;
}

#
# Try to find a macro file -- RETURNS false if the file doesn't exist or MACRO if it does.
# If the file exists, the macro is entered into the 'targets' table and the fully-qualified
# name of the file is stored in the 'macro' table.
#
sub find_macro( $ )
{
    my $macro = $_[0];
    my $macrofile = find_file "macro.$macro";

    if ( -f $macrofile ) {
	$macros{$macro} = $macrofile;
	$targets{$macro} = MACRO;
    } else {
	0;
    }
}

#
# Return ( action, level[:tag] ) from passed full action
#
sub split_action ( $ ) {
    my $action = $_[0];
    my @a = split( /:/ , $action, 4 );
    fatal_error "Invalid ACTION ($action)" if ( $action =~ /::/ ) || ( @a > 3 );
    ( shift @a, join ":", @a );
}

#
# This function substitutes the second argument for the first part of the first argument up to the first colon (":")
#
# Example:
#
#         substitute_param DNAT PARAM:info:FTP
#
#         produces "DNAT:info:FTP"
#
sub substitute_param( $$ ) {
    my ( $param, $action ) = @_;

    if ( $action =~ /:/ ) {
	my $logpart = (split_action $action)[1];
	$logpart =~ s!/$!!;
	return "$param:$logpart";
    }

    $param;
}

#
# Combine fields from a macro body with one from the macro invocation
#
sub merge_macro_source_dest( $$ ) {
    my ( $body, $invocation ) = @_;

    if ( $invocation ) {
	if ( $body ) {
	    return $body if $invocation eq '-';
	    return "$body:$invocation" if $invocation =~ /.*?\.*?\.|^\+|^~|^!~/;
	    return "$invocation:$body";
	}

	return $invocation;
    }

    $body || '';
}

sub merge_macro_column( $$ ) {
    my ( $body, $invocation ) = @_;

    if ( defined $invocation && $invocation ne '' && $invocation ne '-' ) {
	$invocation;
    } else {
	$body;
    }
}

#
# Get Macro Name -- strips away trailing /* and :* from the first column in a rule, macro or action.
#
sub isolate_basic_target( $ ) {
    my $target = ( split '[/:]', $_[0])[0]; 

    $target =~ /^(\w+)[(].*[)]$/ ? $1 : $target;
}

#
# Split the passed target into the basic target and parameter
#
sub get_target_param( $ ) {
    my ( $target, $param ) = split '/', $_[0];

    unless ( defined $param ) {
	( $target, $param ) = ( $1, $2 ) if $target =~ /^(\w+)[(](.*)[)]$/;
    }

    ( $target, $param );
}

#
# Define an Action
#
sub new_action( $ ) {

    my $action = $_[0];

    $actions{$action} = { actchain => '', requires => {} };
}

#
# Record a 'requires' relationship between a pair of actions.
#
sub add_requiredby ( $$ ) {
    my ($requiredby , $requires ) = @_;
    $actions{$requires}{requires}{$requiredby} = 1;
}

#
# Create and record a log action chain -- Log action chains have names
# that are formed from the action name by prepending a "%" and appending
# a 1- or 2-digit sequence number. In the functions that follow,
# the CHAIN, LEVEL and TAG variable serves as arguments to the user's
# exit. We call the exit corresponding to the name of the action but we
# set CHAIN to the name of the iptables chain where rules are to be added.
# Similarly, LEVEL and TAG contain the log level and log tag respectively.
#
# The maximum length of a chain name is 30 characters -- since the log
# action chain name is 2-3 characters longer than the base chain name,
# this function truncates the original chain name where necessary before
# it adds the leading "%" and trailing sequence number.
#
sub createlogactionchain( $$ ) {
    my ( $action, $level ) = @_;
    my $chain = $action;
    my $actionref = $actions{$action};
    my $chainref;
    
    my ($lev, $tag) = split ':', $level;

    validate_level $lev;

    $actionref = new_action $action unless $actionref;

    $chain = substr $chain, 0, 28 if ( length $chain ) > 28;

  CHECKDUP:
    {
	$actionref->{actchain}++ while $chain_table{filter}{'%' . $chain . $actionref->{actchain}};
	$chain = substr( $chain, 0, 27 ), redo CHECKDUP if ( $actionref->{actchain} || 0 ) >= 10 and length $chain == 28;
    }

    $logactionchains{"$action:$level"} = $chainref = new_chain 'filter', '%' . $chain . $actionref->{actchain}++;

    fatal_error "Too many invocations of Action $action" if $actionref->{actchain} > 99;
    
    mark_referenced $chainref; # Just in case the action body is empty.

    unless ( $targets{$action} & STANDARD ) {

	my $file = find_file $chain;

	if ( -f $file ) {
	    progress_message "Processing $file...";

	    ( $level, my $tag ) = split /:/, $level;

	    $tag = $tag || '';

	    unless ( my $return = eval `cat $file` ) {
		fatal_error "Couldn't parse $file: $@" if $@;
		fatal_error "Couldn't do $file: $!"    unless defined $return;
		fatal_error "Couldn't run $file"       unless $return;
	    }
	}
    }
}

sub createsimpleactionchain( $ ) {
    my $action  = shift;
    my $chainref = new_chain 'filter', $action;

    $logactionchains{"$action:none"} = $chainref;

    mark_referenced $chainref; # Just in case the action body is empty.

    unless ( $targets{$action} & STANDARD ) {

	my $file = find_file $action;

	if ( -f $file ) {
	    progress_message "Processing $file...";

	    my ( $level, $tag ) = ( '', '' );

	    unless ( my $return = eval `cat $file` ) {
		fatal_error "Couldn't parse $file: $@" if $@;
		fatal_error "Couldn't do $file: $!"    unless defined $return;
		fatal_error "Couldn't run $file"       unless $return;
	    }
	}
    }
}

#
# Create an action chain and run it's associated user exit
#
sub createactionchain( $ ) {
    my ( $action , $level ) = split_action $_[0];

    my $chainref;

    if ( defined $level && $level ne '' ) {
	if ( $level eq 'none' ) {
	    createsimpleactionchain $action;
	} else {
	    createlogactionchain $action , $level;
	}
    } else {
	createsimpleactionchain $action;
    }
}

#
# Find the chain that handles the passed action. If the chain cannot be found,
# a fatal error is generated and the function does not return.
#
sub find_logactionchain( $ ) {
    my $fullaction = $_[0];
    my ( $action, $level ) = split_action $fullaction;

    $level = 'none' unless $level;

    fatal_error "Fatal error in find_logactionchain" unless $logactionchains{"$action:$level"};
}

#
# The functions process_actions1-3() implement the three phases of action processing.
#
# The first phase (process_actions1) occurs before the rules file is processed. ${SHAREDIR}/actions.std
# and ${CONFDIR}/actions are scanned (in that order) and for each action:
#
#      a) The related action definition file is located and scanned.
#      b) Forward and unresolved action references are trapped as errors.
#      c) A dependency graph is created using the 'requires' field in the 'actions' table.
#
# As the rules file is scanned, each action[:level[:tag]] is merged onto the 'usedactions' hash. When an <action>
# is merged into the hash, its action chain is created. Where logging is specified, a chain with the name
# %<action>n is used where the <action> name is truncated on the right where necessary to ensure that the total
# length of the chain name does not exceed 30 characters.
#
# The second phase (process_actions2) occurs after the rules file is scanned. The transitive closure of
# %usedactions is generated; again, as new actions are merged into the hash, their action chains are created.
#
# The final phase (process_actions3) is to traverse the keys of %usedactions populating each chain appropriately
# by reading the action definition files and creating rules. Note that a given action definition file is
# processed once for each unique [:level[:tag]] applied to an invocation of the action.
#

sub process_macro1 ( $$ ) {
    my ( $action, $macrofile ) = @_;

    progress_message "   ..Expanding Macro $macrofile...";

    push_open( $macrofile );

    while ( read_a_line ) {
	my ( $mtarget, $msource,  $mdest,  $mproto,  $mports,  $msports, $ mrate, $muser ) = split_line1 1, 8, 'macro file';

	next if $mtarget eq 'COMMENT';

	$mtarget =~ s/:.*$//;

	$mtarget = (split '/' , $mtarget)[0];

	my $targettype = $targets{$mtarget};

	$targettype = 0 unless defined $targettype;

	fatal_error "Invalid target ($mtarget)"
	    unless ( $targettype == STANDARD ) || ( $mtarget eq 'PARAM' ) || ( $targettype & ( LOGRULE | NFQ | CHAIN ) );
    }

    progress_message "   ..End Macro $macrofile";

    pop_open;
}

sub process_action1 ( $$ ) {
    my ( $action, $wholetarget ) = @_;

    my ( $target, $level ) = split_action $wholetarget;

    $level = 'none' unless $level;

    my $targettype = $targets{$target};

    if ( defined $targettype ) {
	return if ( $targettype == STANDARD ) || ( $targettype & ( MACRO | LOGRULE |  NFQ | CHAIN ) );

	fatal_error "Invalid TARGET ($target)" if $targettype & STANDARD;

	fatal_error "An action may not invoke itself" if $target eq $action;

	add_requiredby $wholetarget, $action if $targettype & ACTION;
    } elsif ( $target eq 'COMMENT' ) {
	fatal_error "Invalid TARGET ($wholetarget)" unless $wholetarget eq $target;
    } else {
	( $target, my $param ) = get_target_param $target;

	return if $target eq 'NFQUEUE';

	if ( defined $param ) {
	    my $paramtype = $targets{$param} || 0;

	    fatal_error "Parameter value not allowed in action files ($param)" if $paramtype & NATRULE;
	}

	fatal_error "Invalid or missing ACTION ($wholetarget)" unless defined $target;

	if ( find_macro $target ) {
	    process_macro1( $action, $macros{$target} );
	} else {
	    fatal_error "Invalid TARGET ($target)";
	}
    }
}

sub process_actions1() {

    progress_message2 "Preprocessing Action Files...";

    for my $act ( grep $targets{$_} & ACTION , keys %targets ) {
	new_action $act;
    }

    for my $file ( qw/actions.std actions/ ) {
	open_file $file;

	while ( read_a_line ) {
	    my ( $action ) = split_line 1, 1, 'action file';

	    if ( $action =~ /:/ ) {
		warning_message 'Default Actions are now specified in /etc/shorewall/shorewall.conf';
		$action =~ s/:.*$//;
	    }

	    next unless $action;

	    if ( $targets{$action} ) {
		warning_message "Duplicate Action Name ($action) Ignored" unless $targets{$action} & ACTION;
		next;
	    }

	    $targets{$action} = ACTION;

	    fatal_error "Invalid Action Name ($action)" unless "\L$action" =~ /^[a-z]\w*$/;

	    new_action $action;

	    my $actionfile = find_file "action.$action";

	    fatal_error "Missing Action File ($actionfile)" unless -f $actionfile;

	    progress_message2 "   Pre-processing $actionfile...";

	    push_open( $actionfile );

	    while ( read_a_line ) {

		my ($wholetarget, $source, $dest, $proto, $ports, $sports, $rate, $users ) = split_line 1, 8, 'action file';

		process_action1( $action, $wholetarget );

	    }

	    pop_open;
	}
    }
}

sub process_actions2 () {
    progress_message2 'Generating Transitive Closure of Used-action List...';

    my $changed = 1;

    while ( $changed ) {
	$changed = 0;
	for my $target (keys %usedactions) {
	    my ($action, $level) = split_action $target;
	    my $actionref = $actions{$action};
	    fatal_error "Null Action Reference in process_actions2" unless $actionref;
	    for my $action1 ( keys %{$actionref->{requires}} ) {
		my $action2 = merge_levels $target, $action1;
		unless ( $usedactions{ $action2 } ) {
		    $usedactions{ $action2 } = 1;
		    createactionchain $action2;
		    $changed = 1;
		}
	    }
	}
    }
}

#
# This function is called to process each rule generated from an action file.
#
sub process_action( $$$$$$$$$$ ) {
    my ($chainref, $actionname, $target, $source, $dest, $proto, $ports, $sports, $rate, $user ) = @_;

    my ( $action , $level ) = split_action $target;

    if ( $action eq 'REJECT' ) {
	$action = 'reject';
    } elsif ( $action eq 'CONTINUE' ) {
	$action = 'RETURN';
    } elsif ( $action =~ /^NFQUEUE/ ) {
	( $action, my $param ) = get_target_param $action;
	$param = 1 unless defined $param;
	$action = "NFQUEUE --queue-num $param";
    }

    expand_rule ( $chainref ,
		  NO_RESTRICT ,
		  do_proto( $proto, $ports, $sports ) . do_ratelimit( $rate, $action ) . do_user $user ,
		  $source ,
		  $dest ,
		  '', #Original Dest
		  "-j $action" ,
		  $level ,
		  $action ,
		  '' );
}

#
# Expand Macro in action files.
#
sub process_macro3( $$$$$$$$$$$ ) {
    my ( $fn, $param, $chainref, $action, $source, $dest, $proto, $ports, $sports, $rate, $user ) = @_;

    my $nocomment = no_comment;

    progress_message "..Expanding Macro $fn...";

    push_open $fn;

    while ( read_a_line ) {

	my ( $mtarget, $msource, $mdest, $mproto, $mports, $msports, $mrate, $muser ) = split_line1 1, 8, 'macro file';

	if ( $mtarget eq 'COMMENT' ) {
	    process_comment unless $nocomment;
	    next;
	}

	if ( $mtarget =~ /^PARAM:?/ ) {
	    fatal_error 'PARAM requires that a parameter be supplied in macro invocation' unless $param;
	    $mtarget = substitute_param $param,  $mtarget;
	}

	if ( $msource ) {
	    if ( ( $msource eq '-' ) || ( $msource eq 'SOURCE' ) ) {
		$msource = $source || '';
	    } elsif ( $msource eq 'DEST' ) {
		$msource = $dest || '';
	    } else {
		$msource = merge_macro_source_dest $msource, $source;
	    }
	} else {
	    $msource = '';
	}

	$msource = '' if $msource eq '-';

	if ( $mdest ) {
	    if ( ( $mdest eq '-' ) || ( $mdest eq 'DEST' ) ) {
		$mdest = $dest || '';
	    } elsif ( $mdest eq 'SOURCE' ) {
		$mdest = $source || '';
	    } else {
		$mdest = merge_macro_source_dest $mdest, $dest;
	    }
	} else {
	    $mdest = '';
	}

	$mdest   = '' if $mdest eq '-';

	$mproto  = merge_macro_column $mproto,  $proto;
	$mports  = merge_macro_column $mports,  $ports;
	$msports = merge_macro_column $msports, $sports;
	$mrate   = merge_macro_column $mrate,   $rate;
	$muser   = merge_macro_column $muser,   $user;

	process_action $chainref, $action, $mtarget, $msource, $mdest, $mproto, $mports, $msports, $mrate, $muser;
    }

    pop_open;

    progress_message '..End Macro';

    clear_comment unless $nocomment;
}

#
# Generate chain for non-builtin action invocation
#
sub process_action3( $$$$$ ) {
    my ( $chainref, $wholeaction, $action, $level, $tag ) = @_;
    my $actionfile = find_file "action.$action";

    fatal_error "Missing Action File ($actionfile)" unless -f $actionfile;

    progress_message2 "Processing $actionfile for chain $chainref->{name}...";

    open_file $actionfile;

    while ( read_a_line ) {

	my ($target, $source, $dest, $proto, $ports, $sports, $rate, $user ) = split_line1 1, 8, 'action file';

	if ( $target eq 'COMMENT' ) {
	    process_comment;
	    next;
	}

	my $target2 = merge_levels $wholeaction, $target;

	my ( $action2 , $level2 ) = split_action $target2;

	( $action2 , my $param ) = get_target_param $action2;

	my $action2type = $targets{$action2} || 0; 

	unless ( $action2type == STANDARD ) {
	    if ( $action2type & ACTION ) {
		$target2 = (find_logactionchain ( $target = $target2 ))->{name};
	    } else {
		fatal_error "Internal Error" unless $action2type & ( MACRO | LOGRULE | NFQ | CHAIN );
	    }
	}

	if ( $action2type == MACRO ) {
	    fatal_error "Null Macro" unless my $fn = $macros{$action2};

	    process_macro3( $fn, $param, $chainref, $action, $source, $dest, $proto, $ports, $sports, $rate, $user );
	} else {
	    process_action $chainref, $action, $target2, $source, $dest, $proto, $ports, $sports, $rate, $user;
	}
    }

    clear_comment;
}

sub process_actions3 () {
    #
    # The following small functions generate rules for the builtin actions of the same name
    #
    sub dropBcast( $$$ ) {
	my ($chainref, $level, $tag) = @_;

	if ( $capabilities{ADDRTYPE} ) {
	    if ( $level ne '' ) {
		log_rule_limit $level, $chainref, 'dropBcast' , 'DROP', '', $tag, 'add', ' -m addrtype --dst-type BROADCAST ';
		log_rule_limit $level, $chainref, 'dropBcast' , 'DROP', '', $tag, 'add', ' -d 224.0.0.0/4 ';
	    }

	    add_rule $chainref, '-m addrtype --dst-type BROADCAST -j DROP';
	} else {
	    add_command $chainref, 'for address in $ALL_BCASTS; do';
	    incr_cmd_level $chainref;
	    log_rule_limit $level, $chainref, 'dropBcast' , 'DROP', '', $tag, 'add', ' -d $address ' if $level ne '';
	    add_rule $chainref, '-d $address -j DROP';
	    decr_cmd_level $chainref;
	    add_command $chainref, 'done';

	    log_rule_limit $level, $chainref, 'dropBcast' , 'DROP', '', $tag, 'add', ' -d 224.0.0.0/4 ' if $level ne '';
	}

	add_rule $chainref, '-d 224.0.0.0/4 -j DROP';
    }

    sub allowBcast( $$$ ) {
	my ($chainref, $level, $tag) = @_;

	if ( $capabilities{ADDRTYPE} ) {
	    if ( $level ne '' ) {
		log_rule_limit $level, $chainref, 'allowBcast' , 'ACCEPT', '', $tag, 'add', ' -m addrtype --dst-type BROADCAST ';
		log_rule_limit $level, $chainref, 'allowBcast' , 'ACCEPT', '', $tag, 'add', ' -d 224.0.0.0/4 ';
	    }

	    add_rule $chainref, '-m addrtype --dst-type BROADCAST -j ACCEPT';
	} else {
	    add_command $chainref, 'for address in $ALL_BCASTS; do';
	    incr_cmd_level $chainref;
	    log_rule_limit $level, $chainref, 'allowBcast' , 'ACCEPT', '', $tag, 'add', ' -d $address ' if $level ne '';
	    add_rule $chainref, '-d $address -j ACCEPT';
	    decr_cmd_level $chainref;
	    add_command $chainref, 'done';

	    log_rule_limit $level, $chainref, 'allowBcast' , 'ACCEPT', '', $tag, 'add', ' -d 224.0.0.0/4 ' if $level ne '';
	}
	    add_rule $chainref, '-d 224.0.0.0/4 -j ACCEPT';
    }

    sub dropNotSyn ( $$$ ) {
	my ($chainref, $level, $tag) = @_;

	log_rule_limit $level, $chainref, 'dropNotSyn' , 'DROP', '', $tag, 'add', '-p tcp ! --syn ' if $level ne '';
	add_rule $chainref , '-p tcp ! --syn -j DROP';
    }

    sub rejNotSyn ( $$$ ) {
	my ($chainref, $level, $tag) = @_;

	log_rule_limit $level, $chainref, 'rejNotSyn' , 'REJECT', '', $tag, 'add', '-p tcp ! --syn ' if $level ne '';
	add_rule $chainref , '-p tcp ! --syn -j REJECT --reject-with tcp-reset';
    }

    sub dropInvalid ( $$$ ) {
	my ($chainref, $level, $tag) = @_;

	log_rule_limit $level, $chainref, 'dropInvalid' , 'DROP', '', $tag, 'add', '-m state --state INVALID ' if $level ne '';
	add_rule $chainref , '-m state --state INVALID -j DROP';
    }

    sub allowInvalid ( $$$ ) {
	my ($chainref, $level, $tag) = @_;

	log_rule_limit $level, $chainref, 'allowInvalid' , 'ACCEPT', '', $tag, 'add', '-m state --state INVALID ' if $level ne '';
	add_rule $chainref , '-m state --state INVALID -j ACCEPT';
    }

    sub forwardUPnP ( $$$ ) {
    }

    sub allowinUPnP ( $$$ ) {
	my ($chainref, $level, $tag) = @_;

	if ( $level ne '' ) {
	    log_rule_limit $level, $chainref, 'allowinUPnP' , 'ACCEPT', '', $tag, 'add', '-p udp --dport 1900 ';
	    log_rule_limit $level, $chainref, 'allowinUPnP' , 'ACCEPT', '', $tag, 'add', '-p tcp --dport 49152 ';
	}

	add_rule $chainref, '-p udp --dport 1900 -j ACCEPT';
	add_rule $chainref, '-p tcp --dport 49152 -j ACCEPT';
    }

    sub Limit( $$$ ) {
	my ($chainref, $level, $tag) = @_;

	my @tag = split /,/, $tag;

	fatal_error 'Limit rules must include <set name>,<max connections>,<interval> as the log tag (' . join( ':', 'Limit', $level eq '' ? 'none' : $level , $tag ) . ')' unless @tag == 3;

	my $set   = $tag[0];

	for ( @tag[1,2] ) {
	    fatal_error 'Max connections and interval in Limit rules must be numeric (' . join( ':', 'Limit', $level eq '' ? 'none' : $level, $tag ) . ')' unless /^\d+$/
	}

	my $count = $tag[1] + 1;

	require_capability( 'RECENT_MATCH' , 'Limit rules' , '' );

	add_rule $chainref, "-m recent --name $set --set";

	if ( $level ne '' ) {
	    my $xchainref = new_chain 'filter' , "$chainref->{name}%";
	    log_rule_limit $level, $xchainref, $tag[0], 'DROP', '', '', 'add', '';
	    add_rule $xchainref, '-j DROP';
	    add_rule $chainref,  "-m recent --name $set --update --seconds $tag[2] --hitcount $count -j $xchainref->{name}";
	} else {
	    add_rule $chainref, "-m recent --update --name $set --seconds $tag[2] --hitcount $count -j DROP";
	}

	add_rule $chainref, '-j ACCEPT';
    }

    my %builtinops = ( 'dropBcast'    => \&dropBcast,
		       'allowBcast'   => \&allowBcast,
		       'dropNotSyn'   => \&dropNotSyn,
		       'rejNotSyn'    => \&rejNotSyn,
		       'dropInvalid'  => \&dropInvalid,
		       'allowInvalid' => \&allowInvalid,
		       'allowinUPnP'  => \&allowinUPnP,
		       'forwardUPnP'  => \&forwardUPnP,
		       'Limit'        => \&Limit,
		       );

    for my $wholeaction ( keys %usedactions ) {
	my $chainref = find_logactionchain $wholeaction;
	my ( $action, $level, $tag ) = split /:/, $wholeaction;

	$level = '' unless defined $level;
	$tag   = '' unless defined $tag;

	if ( $targets{$action} & BUILTIN ) {
	    $level = '' if $level =~ /none!?/;
	    $builtinops{$action}->($chainref, $level, $tag);
	} else {
	    process_action3 $chainref, $wholeaction, $action, $level, $tag;
	}
    }
}

1;