shorewall_code/Shorewall/action.Drop

#
# Shorewall version 4 - Drop Action
#
# /usr/share/shorewall/action.Drop
#
#	The default DROP common rules
#
#	This action is invoked before a DROP policy is enforced. The purpose
#	of the action is:
#
#	a) Avoid logging lots of useless cruft.
#	b) Allow 'auth' requests rejected rejected, even if the policy is
#	   DROP. Otherwise, you may experience problems establishing
#	   connections with servers that use auth.
#	c) Ensure that certain ICMP packets that are necessary for successful
#	   internet operation are always ACCEPTed.
#
#  The action accepts five optional parameters:
#
#	1 - 'audit' or '-'. Default is '-' which means don't audit in builtin
#           actions.
#       2 - Action to take with Auth requests. Default is to do nothing special
#	    with them.
#	3 - Action to take with SMB requests. Default is DROP or A_DROP,
#           depending on the setting of the first parameter.
#       4 - Action to take with required ICMP packets. Default is ACCEPT or
#           A_ACCEPT depending on the first parameter.
#       5 - Action to take with late UDP replies (UDP source port 53). Default
#           is DROP or A_DROP depending on the first parameter.
#
# IF YOU ARE HAVING CONNECTION PROBLEMS, CHANGING THIS FILE WON'T HELP!!!!!!!!!
#
###############################################################################
?FORMAT 2
#
# The following magic provides different defaults for @2 thru @5, when @1 is
# 'audit'.
#
?BEGIN PERL;
use Shorewall::Config;

my ( $p1, $p2, $p3 , $p4, $p5 ) = get_action_params( 5 );

if ( defined $p1 ) {
    if ( $p1 eq 'audit' ) {
	set_action_param( 3, 'A_DROP')     unless supplied $p3;
	set_action_param( 4, 'A_ACCEPT' )  unless supplied $p4;
	set_action_param( 5, 'A_DROP' )    unless supplied $p5;
    } else {
	fatal_error "Invalid value ($p1) for first Drop parameter" if supplied $p1;
    }
}

1;

?END PERL;

DEFAULTS -,-,DROP,ACCEPT,DROP

#TARGET		SOURCE	DEST	PROTO	DPORT	SPORT
#
# Count packets that come through here
#
COUNT
#
# Special Handling for Auth
#
?if @2 ne '-'
Auth(@2)
?endif
#
# Don't log broadcasts
#
Broadcast(DROP,@1)
#
# ACCEPT critical ICMP types
#
AllowICMPs(@4)	-	-	icmp
#
# Drop packets that are in the INVALID state -- these are usually ICMP packets
# and just confuse people when they appear in the log.
#
Invalid(DROP,@1)
#
# Drop Microsoft noise so that it doesn't clutter up the log.
#
SMB(@3)
DropUPnP(@5)
#
# Drop 'newnotsyn' traffic so that it doesn't get logged.
#
NotSyn(DROP,@1)	-	-	tcp
#
# Drop late-arriving DNS replies. These are just a nuisance and clutter up
# the log.
#
DropDNSrep(@5)