firewall: rules.pl: Refactored entire script.

config/firewall/rules.pl

@@ -31,25 +31,27 @@ my $DEBUG = 0;
 my $IPTABLES = "iptables --wait";
 
 # iptables chains
-my $CHAIN                 = "FORWARDFW";
+my $CHAIN_INPUT           = "INPUTFW";
+my $CHAIN_FORWARD         = "FORWARDFW";
+my $CHAIN_OUTPUT          = "OUTPUTFW";
+my $CHAIN                 = $CHAIN_FORWARD;
 my $CHAIN_NAT_SOURCE      = "NAT_SOURCE";
 my $CHAIN_NAT_DESTINATION = "NAT_DESTINATION";
+my @VALID_CHAINS          = ($CHAIN_INPUT, $CHAIN_FORWARD, $CHAIN_OUTPUT);
+
+my @PROTOCOLS = ("tcp", "udp", "icmp", "igmp", "ah", "esp", "gre", "ipv6", "ipip");
+my @PROTOCOLS_WITH_PORTS = ("tcp", "udp");
+
+my @VALID_TARGETS = ("ACCEPT", "DROP", "REJECT");
 
 my %fwdfwsettings=();
 my %defaultNetworks=();
-my %configfwdfw=();
-my %color=();
-my %icmptypes=();
-my %ovpnSettings=();
+my %configfwdfw=();;
 my %customgrp=();
-our %sourcehash=();
-our %targethash=();
-my @timeframe=();
 my %configinputfw=();
 my %configoutgoingfw=();
 my %confignatfw=();
 my %aliases=();
-my @DPROT=();
 my @p2ps=();
 
 my $configfwdfw		= "${General::swroot}/firewall/config";
@@ -58,14 +60,6 @@ my $configoutgoing  = "${General::swroot}/firewall/outgoing";
 my $p2pfile			= "${General::swroot}/firewall/p2protocols";
 my $configgrp		= "${General::swroot}/fwhosts/customgroups";
 my $netsettings		= "${General::swroot}/ethernet/settings";
-my $errormessage	= '';
-my $orange			= '';
-my $green			= '';
-my $blue			= '';
-my ($TYPE,$PROT,$SPROT,$DPROT,$SPORT,$DPORT,$SRC_TGT);
-my $conexists		= 'off';
-my $dnat			='';
-my $snat			='';
 
 &General::readhash("${General::swroot}/firewall/settings", \%fwdfwsettings);
 &General::readhash("$netsettings", \%defaultNetworks);
@@ -75,19 +69,6 @@ my $snat			='';
 &General::readhasharray($configgrp, \%customgrp);
 &General::get_aliases(\%aliases);
 
-#check if we have an internetconnection
-open (CONN,"/var/ipfire/red/iface");
-my $con = <CONN>;
-close(CONN);
-
-if (-f "/var/ipfire/red/active"){
-	$conexists='on';
-}
-
-open (CONN1,"/var/ipfire/red/local-ipaddress");
-my $redip = <CONN1>;
-close(CONN1);
-
 # MAIN
 &main();
 
@@ -122,6 +103,18 @@ sub print_error {
 	print STDERR "$message\n";
 }
 
+sub print_rule {
+	my $hash = shift;
+
+	print "\nRULE:";
+
+	my $i = 0;
+	foreach (@$hash) {
+		printf("  %2d: %s", $i++, $_);
+	}
+	print "\n";
+}
+
 sub flush {
 	run("$IPTABLES -F FORWARDFW");
 	run("$IPTABLES -F INPUTFW");
@@ -143,272 +136,249 @@ sub preparerules {
 }
 
 sub buildrules {
-	my $hash=shift;
-	my $STAG;
-	my $snatport;
-	my $fireport;
-	my $fwaccessdport;
-	my $natchain;
-	my $icmptype;
-	foreach my $key (sort {$a <=> $b} keys %$hash){
-		next if (($$hash{$key}[6] eq 'RED' || $$hash{$key}[6] eq 'RED1') && $conexists eq 'off' );
+	my $hash = shift;
 
-		my $time_constraints = "";
-		my $natip = "";
+	foreach my $key (sort {$a <=> $b} keys %$hash) {
+		# Skip disabled rules.
+		next unless ($$hash{$key}[2] eq 'ON');
 
-		# Check if logging should be enabled.
-		my $LOG = 0;
-		if ($$hash{$key}[17] eq 'ON') {
-			$LOG = 1;
+		if ($DEBUG) {
+			print_rule($$hash{$key});
 		}
 
-		my $NAT = 0;
-		my $NAT_MODE;
+		# Check if the target is valid.
+		my $target = $$hash{$key}[0];
+		if (!$target ~~ @VALID_TARGETS) {
+			print_error("Invalid target '$target' for rule $key");
+			next;
+		}
+
+		# Check if the chain is valid.
+		my $chain = $$hash{$key}[1];
+		if (!$chain ~~ @VALID_CHAINS) {
+			print_error("Invalid chain '$chain' in rule $key");
+			next;
+		}
+
+		# Collect all sources.
+		my @sources = &get_addresses($hash, $key, "src");
+
+		# Collect all destinations.
+		my @destinations = &get_addresses($hash, $key, "tgt");
+
+		my $time_constraints = "";
+
+		# Check if logging should be enabled.
+		my $LOG = ($$hash{$key}[17] eq 'ON');
 
 		# Check if NAT is enabled and initialize variables, that we use for that.
-		if ($$hash{$key}[28] eq 'ON') {
-			$NAT = 1;
+		my $NAT = ($$hash{$key}[28] eq 'ON');
+		my $NAT_MODE;
+		if ($NAT) {
+			$NAT_MODE = uc($$hash{$key}[31]);
+		}
 
-			# Destination NAT
-			if ($$hash{$key}[31] eq 'dnat') {
-				$NAT_MODE = "DNAT";
+		# Set up time constraints.
+		my @time_options = ();
+		if ($$hash{$key}[18] eq 'ON') {
+			push(@time_options, ("-m", "time"));
 
-				if ($$hash{$key}[30] =~ /\|/) {
-					$$hash{$key}[30]=~ tr/|/,/;
-					$fireport='-m multiport --dport '.$$hash{$key}[30];
-				} else {
-					$fireport='--dport '.$$hash{$key}[30] if ($$hash{$key}[30]>0);
-				}
+			# Select all days of the week this match is active.
+			my @weekdays = ();
+			if ($$hash{$key}[19] ne '') {
+				push (@weekdays, "Mon");
+			}
+			if ($$hash{$key}[20] ne '') {
+				push (@weekdays, "Tue");
+			}
+			if ($$hash{$key}[21] ne '') {
+				push (@weekdays, "Wed");
+			}
+			if ($$hash{$key}[22] ne '') {
+				push (@weekdays, "Thu");
+			}
+			if ($$hash{$key}[23] ne '') {
+				push (@weekdays, "Fri");
+			}
+			if ($$hash{$key}[24] ne '') {
+				push (@weekdays, "Sat");
+			}
+			if ($$hash{$key}[25] ne '') {
+				push (@weekdays, "Sun");
+			}
+			if (@weekdays) {
+				push(@time_options, ("--weekdays", join(",", @weekdays)));
+			}
 
-			# Source NAT
-			} elsif ($$hash{$key}[31] eq 'snat') {
-				$NAT_MODE = "SNAT";
+			# Convert start time.
+			my $time_start = &format_time($$hash{$key}[26]);
+			if ($time_start) {
+				push(@time_options, ("--timestart", $time_start));
+			}
 
-			} else {
-				print_error("Invalid NAT mode: $$hash{$key}[31]");
+			# Convert end time.
+			my $time_stop = &format_time($$hash{$key}[27]);
+			if ($time_stop) {
+				push(@time_options, ("--timestop", $time_stop));
+			}
+		}
+
+		# Check which protocols are used in this rule and so that we can
+		# later group rules by protocols.
+		my @protocols = &get_protocols($hash, $key);
+		if (!@protocols) {
+			print_error("Invalid protocol configuration for rule $key");
+			next;
+		}
+
+		foreach my $protocol (@protocols) {
+			# Check if the given protocol is supported.
+			if (($protocol ne "all") && (!$protocol ~~ @PROTOCOLS)) {
+				print_error("Protocol $protocol is not supported (rule $key)");
 				next;
 			}
 
-			$natip = &get_nat_ip($$hash{$key}[29], $NAT_MODE);
-		}
+			# Prepare protocol options (like ICMP types, ports, etc...).
+			my @protocol_options = &get_protocol_options($hash, $key, $protocol);
 
-		$STAG='';
-		if($$hash{$key}[2] eq 'ON'){
-			#get source ip's
-			if ($$hash{$key}[3] eq 'cust_grp_src'){
-				foreach my $grp (sort {$a <=> $b} keys %customgrp){
-						if($customgrp{$grp}[0] eq $$hash{$key}[4]){
-						&get_address($customgrp{$grp}[3],$customgrp{$grp}[2],"src");
+			# Check if this protocol knows ports.
+			my $protocol_has_ports = ($protocol ~~ @PROTOCOLS_WITH_PORTS);
+
+			foreach my $source (@sources) {
+				foreach my $destination (@destinations) {
+					# Skip invalid rules.
+					next if (!$source || !$destination || ($destination eq "none"));
+
+					# Array with iptables arguments.
+					my @options = ();
+
+					# Append protocol.
+					if ($protocol ne "all") {
+						push(@options, ("-p", $protocol));
+						push(@options, @protocol_options);
 					}
-				}
-			}else{
-				&get_address($$hash{$key}[3],$$hash{$key}[4],"src");
-			}
-			#get target ip's
-			if ($$hash{$key}[5] eq 'cust_grp_tgt'){
-				foreach my $grp (sort {$a <=> $b} keys %customgrp){
-					if($customgrp{$grp}[0] eq $$hash{$key}[6]){
-						&get_address($customgrp{$grp}[3],$customgrp{$grp}[2],"tgt");
+
+					# Append source.
+					if ($source =~ /mac/) {
+						push(@options, $source);
+					} else {
+						push(@options, ("-s", $source));
 					}
-				}
-			}elsif($$hash{$key}[5] eq 'ipfire' ){
-				if($$hash{$key}[6] eq 'GREEN'){
-					$targethash{$key}[0]=$defaultNetworks{'GREEN_ADDRESS'};
-				}
-				if($$hash{$key}[6] eq 'BLUE'){
-					$targethash{$key}[0]=$defaultNetworks{'BLUE_ADDRESS'};
-				}
-				if($$hash{$key}[6] eq 'ORANGE'){
-					$targethash{$key}[0]=$defaultNetworks{'ORANGE_ADDRESS'};
-				}
-				if($$hash{$key}[6] eq 'ALL'){
-					$targethash{$key}[0]='0.0.0.0/0';
-				}
-				if($$hash{$key}[6] eq 'RED' || $$hash{$key}[6] eq 'RED1'){
-					open(FILE, "/var/ipfire/red/local-ipaddress")or die "Couldn't open local-ipaddress";
-					$targethash{$key}[0]= <FILE>;
-					close(FILE);
-				}else{
-					foreach my $alias (sort keys %aliases){
-						if ($$hash{$key}[6] eq $alias){
-							$targethash{$key}[0]=$aliases{$alias}{'IPT'};
-						}
+
+					# Append destination for non-DNAT rules.
+					unless ($NAT && ($NAT_MODE eq "DNAT")) {
+						push(@options, ("-d", $destination));
 					}
-				}
-			}else{
-				&get_address($$hash{$key}[5],$$hash{$key}[6],"tgt");
-			}
-			##get source prot and port
-			$SRC_TGT='SRC';
-			$SPORT = &get_port($hash,$key);
-			$SRC_TGT='';
 
-			##get target prot and port
-			$DPROT=&get_prot($hash,$key);
+					# Add time constraint options.
+					push(@options, @time_options);
 
-			if ($DPROT eq ''){$DPROT=' ';}
-			@DPROT=split(",",$DPROT);
+					# Process NAT rules.
+					if ($NAT) {
+						my $nat_address = &get_nat_address($$hash{$key}[29]);
 
-			# Set up time constraints.
-			if ($$hash{$key}[18] eq 'ON') {
-				my @time_args = ("-m", "time");
+						# Skip NAT rules if the NAT address is unknown
+						# (i.e. no internet connection has been established, yet).
+						next unless ($nat_address);
 
-				# Select all days of the week this match is active.
-				my @weekdays = ();
-				if ($$hash{$key}[19] ne '') {
-					push (@weekdays, "Mon");
-				}
-				if ($$hash{$key}[20] ne '') {
-					push (@weekdays, "Tue");
-				}
-				if ($$hash{$key}[21] ne '') {
-					push (@weekdays, "Wed");
-				}
-				if ($$hash{$key}[22] ne '') {
-					push (@weekdays, "Thu");
-				}
-				if ($$hash{$key}[23] ne '') {
-					push (@weekdays, "Fri");
-				}
-				if ($$hash{$key}[24] ne '') {
-					push (@weekdays, "Sat");
-				}
-				if ($$hash{$key}[25] ne '') {
-					push (@weekdays, "Sun");
-				}
-				if (@weekdays) {
-					push(@time_args, ("--weekdays", join(",", @weekdays)));
-				}
+						# Destination NAT
+						if ($NAT_MODE eq "DNAT") {
+							my ($dnat_address, $dnat_mask) = split("/", $destination);
 
-				# Convert start time.
-				my $time_start = &format_time($$hash{$key}[26]);
-				if ($time_start) {
-					push(@time_args, ("--timestart", $time_start));
-				}
+							my @nat_options = @options;
+							push(@nat_options, ("-d", $nat_address));
+							push(@options,     ("-d", $dnat_address));
 
-				# Convert end time.
-				my $time_stop = &format_time($$hash{$key}[27]);
-				if ($time_stop) {
-					push(@time_args, ("--timestop", $time_stop));
-				}
+							if ($protocol_has_ports) {
+								my $dnat_port = &get_dnat_target_port($hash, $key);
 
-				# Format command line.
-				$time_constraints = join(" ", @time_args);
-			}
+								if ($dnat_port) {
+									$dnat_address .= ":$dnat_port";
 
-			foreach my $DPROT (@DPROT){
-				$DPORT = &get_port($hash,$key,$DPROT);
-				$PROT=$DPROT;
-				$PROT="-p $PROT" if ($PROT ne '' && $PROT ne ' ');
-				if ($DPROT ne 'TCP' && $DPROT ne'UDP' && $DPROT ne 'ICMP' ){
-					$DPORT='';
-				}
-				foreach my $a (sort keys %sourcehash){
-					foreach my $b (sort keys %targethash){
-						if(! $sourcehash{$a}[0] || ! $targethash{$b}[0] || ($natip eq '-d ' && $NAT) || (!$natip && $NAT)){
-							#Skip rules when no RED IP is set (DHCP,DSL)
-							next;
-						}
-						next if ($targethash{$b}[0] eq 'none');
-						$STAG='';
-						if ($sourcehash{$a}[0] ne $targethash{$b}[0] && $targethash{$b}[0] ne 'none' || $sourcehash{$a}[0] eq '0.0.0.0/0.0.0.0'){
-							if($DPROT ne ''){
-								if(substr($sourcehash{$a}[0], 3, 3) ne 'mac' && $sourcehash{$a}[0] ne ''){ $STAG="-s";}
-								#Process ICMP RULE
-								if(substr($DPORT, 2, 4) eq 'icmp'){
-									my @icmprule= split(",",substr($DPORT, 12,));
-									foreach (@icmprule){
-										$icmptype="--icmp-type ";
-										if ($_ eq "BLANK") {
-												$icmptype="";
-												$_="";
+									# Replace --dport with the translated one.
+									my @new_options = ();
+									my $skip_count = 0;
+									foreach my $option (@options) {
+										next if ($skip_count-- > 0);
+
+										if ($option eq "--dport") {
+											push(@new_options, ("--dport", $dnat_port));
+											$skip_count = 1;
+											next;
 										}
-										if ($LOG) {
-											run("$IPTABLES -A $$hash{$key}[1] $PROT $STAG $sourcehash{$a}[0] $SPORT -d $targethash{$b}[0] $icmptype $_ $time_constraints -j LOG");
-										}
-										run("$IPTABLES -A $$hash{$key}[1] $PROT $STAG $sourcehash{$a}[0] $SPORT -d $targethash{$b}[0] $icmptype $_ $time_constraints -j $$hash{$key}[0]");
+
+										push(@new_options, $option);
 									}
-								#PROCESS DNAT RULE (Portforward)
-								} elsif ($NAT && $NAT_MODE eq "DNAT") {
-									if ($LOG) {
-										run("$IPTABLES -t nat -A $CHAIN_NAT_DESTINATION $PROT $STAG $sourcehash{$a}[0] $SPORT $natip $fireport $time_constraints -j LOG --log-prefix 'DNAT'");
-									}
-									my ($ip,$sub) =split("/",$targethash{$b}[0]);
-									#Process NAT with servicegroup used
-									if ($$hash{$key}[14] eq 'cust_srvgrp') {
-										run("$IPTABLES -t nat -A $CHAIN_NAT_DESTINATION $PROT $STAG $sourcehash{$a}[0] $SPORT $natip $fireport $time_constraints -j DNAT --to-destination $ip $DPORT");
-										$fwaccessdport=$DPORT;
-									} else {
-										run("$IPTABLES -t nat -A $CHAIN_NAT_DESTINATION $PROT $STAG $sourcehash{$a}[0] $SPORT $natip $fireport $time_constraints -j DNAT --to-destination $ip$DPORT");
-										$DPORT =~ s/\-/:/g;
-										if ($DPORT){
-											$fwaccessdport="--dport ".substr($DPORT,1,);
-										}elsif(! $DPORT && $$hash{$key}[30] ne ''){
-											if ($$hash{$key}[30]=~m/|/i){
-												$$hash{$key}[30] =~ s/\|/,/g;
-												$fwaccessdport="-m multiport --dport $$hash{$key}[30]";
-											}else{
-												$fwaccessdport="--dport $$hash{$key}[30]";
-											}
-										}
-									}
-									run("$IPTABLES -A FORWARDFW $PROT $STAG $sourcehash{$a}[0] -d $ip $fwaccessdport $time_constraints -j $$hash{$key}[0]");
-									next;
-								#PROCESS SNAT RULE
-								} elsif ($NAT && $NAT_MODE eq "SNAT") {
-									if ($LOG) {
-										run("$IPTABLES -t nat -A $CHAIN_NAT_SOURCE $PROT $STAG $sourcehash{$a}[0] $SPORT -d $targethash{$b}[0] $DPORT $time_constraints -j LOG --log-prefix 'SNAT'");
-									}
-									run("$IPTABLES -t nat -A $CHAIN_NAT_SOURCE $PROT $STAG $sourcehash{$a}[0] $SPORT -d $targethash{$b}[0] $DPORT $time_constraints -j SNAT --to-source $natip");
-								}
-								#PROCESS EVERY OTHER RULE (If NOT ICMP, else the rule would be applied double)
-								if ($PROT ne '-p ICMP'){
-									if ($LOG && !$NAT) {
-										run("$IPTABLES -A $$hash{$key}[1] $PROT $STAG $sourcehash{$a}[0] $SPORT -d $targethash{$b}[0] $DPORT $time_constraints -j LOG");
-									}
-									run("$IPTABLES -A $$hash{$key}[1] $PROT $STAG $sourcehash{$a}[0] $SPORT -d $targethash{$b}[0] $DPORT $time_constraints -j $$hash{$key}[0]");
-								}
-								#PROCESS Prot ICMP and type = All ICMP-Types
-								if ($PROT eq '-p ICMP' && $$hash{$key}[9] eq 'All ICMP-Types'){
-									if ($LOG && !$NAT) {
-										run("$IPTABLES -A $$hash{$key}[1] $PROT $STAG $sourcehash{$a}[0] $SPORT -d $targethash{$b}[0] $DPORT $time_constraints -j LOG");
-									}
-									run("$IPTABLES -A $$hash{$key}[1] $PROT $STAG $sourcehash{$a}[0] $SPORT -d $targethash{$b}[0] $DPORT $time_constraints -j $$hash{$key}[0]");
+									@options = @new_options;
 								}
 							}
+
+							if ($LOG) {
+								run("$IPTABLES -t nat -A $CHAIN_NAT_DESTINATION @nat_options -j LOG --log-prefix 'DNAT'");
+							}
+							run("$IPTABLES -t nat -A $CHAIN_NAT_DESTINATION @nat_options -j DNAT --to-destination $dnat_address");
+
+						# Source NAT
+						} elsif ($NAT_MODE eq "SNAT") {
+							if ($LOG) {
+								run("$IPTABLES -t nat -A $CHAIN_NAT_SOURCE @options -j LOG --log-prefix 'SNAT'");
+							}
+							run("$IPTABLES -t nat -A $CHAIN_NAT_SOURCE @options -j SNAT --to-source $nat_address");
 						}
 					}
+
+					# Insert firewall rule.
+					if ($LOG && !$NAT) {
+						run("$IPTABLES -A $chain @options -j LOG");
+					}
+					run("$IPTABLES -A $chain @options -j $target");
 				}
 			}
 		}
-		%sourcehash=();
-		%targethash=();
-		undef $fireport;
 	}
 }
 
-sub get_nat_ip {
-	my $val=shift;
-	my $type=shift;
-	my $result;
-	if($val eq 'RED' || $val eq 'GREEN' || $val eq 'ORANGE' || $val eq 'BLUE'){
-		$result=$defaultNetworks{$val.'_ADDRESS'};
-	}elsif($val eq 'ALL'){
-		$result='-i '.$con;
-	}elsif($val eq 'Default IP' && $type eq "DNAT"){
-		$result='-d '.$redip;
-	}elsif($val eq 'Default IP' && $type eq "SNAT"){
-		$result=$redip;
-	}else{
-		foreach my $al (sort keys %aliases){
-			if($val eq $al && $type eq "DNAT"){
-				$result='-d '.$aliases{$al}{'IPT'};
-			}elsif($val eq $al && $type eq "SNAT"){
-				$result=$aliases{$al}{'IPT'};
-			}
+sub get_external_interface() {
+	open(IFACE, "/var/ipfire/red/iface") or return "";
+	my $iface = <IFACE>;
+	close(IFACE);
+
+	return $iface;
+}
+
+sub get_external_address() {
+	open(ADDR, "/var/ipfire/red/local-ipaddress") or return "";
+	my $address = <ADDR>;
+	close(ADDR);
+
+	return $address;
+}
+
+sub get_alias {
+	my $id = shift;
+
+	foreach my $alias (sort keys %aliases) {
+		if ($id eq $alias) {
+			return $aliases{$alias};
 		}
 	}
-	return $result;
+}
+
+sub get_nat_address {
+	my $zone = shift;
+
+	# Any static address of any zone.
+	if ($zone eq "RED" || $zone eq "GREEN" || $zone eq "ORANGE" || $zone eq "BLUE") {
+		return $defaultNetworks{$zone . "_ADDRESS"};
+
+	} elsif ($zone eq "Default IP") {
+		return &get_external_address();
+
+	} else {
+		return &get_alias($zone);
+	}
+
+	print_error("Could not find NAT address");
 }
 
 # Formats the given timestamp into the iptables format which is "hh:mm" UTC.
@@ -476,156 +446,291 @@ sub p2pblock {
 	}
 }
 
+sub get_addresses {
+	my $hash = shift;
+	my $key  = shift;
+	my $type = shift;
+
+	my @addresses = ();
+	my $addr_type;
+	my $value;
+	my $group_name;
+
+	if ($type eq "src") {
+		$addr_type = $$hash{$key}[3];
+		$value = $$hash{$key}[4];
+
+	} elsif ($type eq "tgt") {
+		$addr_type = $$hash{$key}[5];
+		$value = $$hash{$key}[6];
+	}
+
+	if ($addr_type ~~ ["cust_grp_src", "cust_grp_tgt"]) {
+		foreach my $grp (sort {$a <=> $b} keys %customgrp) {
+			if ($customgrp{$grp}[0] eq $value) {
+				my @address = &get_address($customgrp{$grp}[3], $customgrp{$grp}[2], $type);
+
+				if (@address) {
+					push(@addresses, @address);
+				}
+			}
+		}
+	} else {
+		my @address = &get_address($addr_type, $value, $type);
+
+		if (@address) {
+			push(@addresses, @address);
+		}
+	}
+
+	return @addresses;
+}
+
 sub get_address {
-	my $base=shift; #source of checking ($configfwdfw{$key}[x] or groupkey
-	my $base2=shift;
-	my $type=shift; #src or tgt
-	my $hash;
-	if ($type eq 'src'){
-		$hash=\%sourcehash;
-	}else{
-		$hash=\%targethash;
-	}
-	my $key = &General::findhasharraykey($hash);
-	if($base eq 'src_addr' || $base eq 'tgt_addr' ){
-		if (&General::validmac($base2)){
-			$$hash{$key}[0] = "-m mac --mac-source $base2";
-		}else{
-			$$hash{$key}[0] = $base2;
+	my $key   = shift;
+	my $value = shift;
+	my $type  = shift;
+
+	my @ret = ();
+
+	# If the user manually typed an address, we just check if it is a MAC
+	# address. Otherwise, we assume that it is an IP address.
+	if ($key ~~ ["src_addr", "tgt_addr"]) {
+		if (&General::validmac($value)) {
+			push(@ret, "-m mac --mac-source $value");
+		} else {
+			push(@ret, $value);
 		}
-	}elsif($base eq 'std_net_src' || $base eq 'std_net_tgt' || $base eq 'Standard Network'){
-		$$hash{$key}[0]=&fwlib::get_std_net_ip($base2,$con);
-	}elsif($base eq 'cust_net_src' || $base eq 'cust_net_tgt' || $base eq 'Custom Network'){
-		$$hash{$key}[0]=&fwlib::get_net_ip($base2);
-	}elsif($base eq 'cust_host_src' || $base eq 'cust_host_tgt' || $base eq 'Custom Host'){
-		$$hash{$key}[0]=&fwlib::get_host_ip($base2,$type);
-	}elsif($base eq 'ovpn_net_src' || $base eq 'ovpn_net_tgt' || $base eq 'OpenVPN static network'){
-		$$hash{$key}[0]=&fwlib::get_ovpn_net_ip($base2,1);
-	}elsif($base eq 'ovpn_host_src' ||$base eq 'ovpn_host_tgt' || $base eq 'OpenVPN static host'){
-		$$hash{$key}[0]=&fwlib::get_ovpn_host_ip($base2,33);
-	}elsif($base eq 'ovpn_n2n_src' ||$base eq 'ovpn_n2n_tgt' || $base eq 'OpenVPN N-2-N'){
-		$$hash{$key}[0]=&fwlib::get_ovpn_n2n_ip($base2,11);
-	}elsif($base eq 'ipsec_net_src' || $base eq 'ipsec_net_tgt' || $base eq 'IpSec Network'){
-		$$hash{$key}[0]=&fwlib::get_ipsec_net_ip($base2,11);
-	}elsif($base eq 'ipfire_src' ){
-		if($base2 eq 'GREEN'){
-			$$hash{$key}[0]=$defaultNetworks{'GREEN_ADDRESS'};
+
+	# If a default network interface (GREEN, BLUE, etc.) is selected, we
+	# try to get the corresponding address of the network.
+	} elsif ($key ~~ ["std_net_src", "std_net_tgt", "Standard Network"]) {
+		my $external_interface = &get_external_interface();
+
+		my $network_address = &fwlib::get_std_net_ip($value, $external_interface);
+		if ($network_address) {
+			push(@ret, $network_address);
 		}
-		if($base2 eq 'BLUE'){
-			$$hash{$key}[0]=$defaultNetworks{'BLUE_ADDRESS'};
+
+	# Custom networks.
+	} elsif ($key ~~ ["cust_net_src", "cust_net_tgt", "Custom Network"]) {
+		my $network_address = &fwlib::get_net_ip($value);
+		if ($network_address) {
+			push(@ret, $network_address);
 		}
-		if($base2 eq 'ORANGE'){
-			$$hash{$key}[0]=$defaultNetworks{'ORANGE_ADDRESS'};
+
+	# Custom hosts.
+	} elsif ($key ~~ ["cust_host_src", "cust_host_tgt", "Custom Host"]) {
+		my $host_address = &fwlib::get_host_ip($value, $type);
+		if ($host_address) {
+			push(@ret, $host_address);
 		}
-		if($base2 eq 'ALL'){
-			$$hash{$key}[0]='0.0.0.0/0';
+
+	# OpenVPN networks.
+	} elsif ($key ~~ ["ovpn_net_src", "ovpn_net_tgt", "OpenVPN static network"]) {
+		my $network_address = &fwlib::get_ovpn_net_ip($value, 1);
+		if ($network_address) {
+			push(@ret, $network_address);
 		}
-		if($base2 eq 'RED' || $base2 eq 'RED1'){
-			open(FILE, "/var/ipfire/red/local-ipaddress");
-			$$hash{$key}[0]= <FILE>;
-			close(FILE);
-		}else{
-			foreach my $alias (sort keys %aliases){
-				if ($base2 eq $alias){
-					$$hash{$key}[0]=$aliases{$alias}{'IPT'};
-				}
+
+	# OpenVPN hosts.
+	} elsif ($key ~~ ["ovpn_host_src", "ovpn_host_tgt", "OpenVPN static host"]) {
+		my $host_address = &fwlib::get_ovpn_host_ip($value, 33);
+		if ($host_address) {
+			push(@ret, $host_address);
+		}
+
+	# OpenVPN N2N.
+	} elsif ($key ~~ ["ovpn_n2n_src", "ovpn_n2n_tgt", "OpenVPN N-2-N"]) {
+		my $network_address = &fwlib::get_ovpn_n2n_ip($value, 11);
+		if ($network_address) {
+			push(@ret, $network_address);
+		}
+
+	# IPsec networks.
+	} elsif ($key ~~ ["ipsec_net_src", "ipsec_net_tgt", "IpSec Network"]) {
+		my $network_address = &fwlib::get_ipsec_net_ip($value, 11);
+		if ($network_address) {
+			push(@ret, $network_address);
+		}
+
+	# The firewall's own IP addresses.
+	} elsif ($key ~~ ["ipfire", "ipfire_src"]) {
+		# ALL
+		if ($value eq "ALL") {
+			push(@ret, "0/0");
+
+		# GREEN
+		} elsif ($value eq "GREEN") {
+			push(@ret, $defaultNetworks{"GREEN_ADDRESS"});
+
+		# BLUE
+		} elsif ($value eq "BLUE") {
+			push(@ret, $defaultNetworks{"BLUE_ADDRESS"});
+
+		# ORANGE
+		} elsif ($value eq "ORANGE") {
+			push(@ret, $defaultNetworks{"ORANGE_ADDRESS"});
+
+		# RED
+		} elsif ($value ~~ ["RED", "RED1"]) {
+			my $address = &get_external_address();
+			if ($address) {
+				push(@ret, $address);
+			}
+
+		# Aliases
+		} else {
+			my %alias = &get_alias($value);
+			if (%alias) {
+				push(@ret, $alias{"IPT"});
 			}
 		}
+
+	# If nothing was selected, we assume "any".
+	} else {
+		push(@ret, "0/0");
 	}
+
+	return @ret;
 }
 
-sub get_prot {
-	my $hash=shift;
-	my $key=shift;
-	#check AH,GRE,ESP or ICMP
-	if ($$hash{$key}[7] ne 'ON' && $$hash{$key}[11] ne 'ON'){
-		return "$$hash{$key}[8]";
-	}
-	if ($$hash{$key}[7] eq 'ON' || $$hash{$key}[11] eq 'ON'){
-		#check if servicegroup or service
-		if($$hash{$key}[14] eq 'cust_srv'){
-			return &fwlib::get_srv_prot($$hash{$key}[15]);
-		}elsif($$hash{$key}[14] eq 'cust_srvgrp'){
-			return &fwlib::get_srvgrp_prot($$hash{$key}[15]);
-		}elsif (($$hash{$key}[10] ne '' || $$hash{$key}[15] ne '') && $$hash{$key}[8] eq ''){ #when ports are used and prot set to "all"
-			return "TCP,UDP";
-		}elsif (($$hash{$key}[10] ne '' || $$hash{$key}[15] ne '') && ($$hash{$key}[8] eq 'TCP' || $$hash{$key}[8] eq 'UDP')){ #when ports are used and prot set to "tcp" or "udp"
-			return "$$hash{$key}[8]";
-		}elsif (($$hash{$key}[10] eq '' && $$hash{$key}[15] eq '') && $$hash{$key}[8] ne 'ICMP'){ #when ports are NOT used and prot NOT set to "ICMP"
-			return "$$hash{$key}[8]";
-		}else{
-			return "$$hash{$key}[8]";
+sub get_protocols {
+	my $hash = shift;
+	my $key = shift;
+
+	my $uses_source_ports = ($$hash{$key}[7] eq "ON");
+	my $uses_services = ($$hash{$key}[11] eq "ON");
+
+	my @protocols = ();
+
+	# Rules which don't have source ports or services (like ICMP, ESP, ...).
+	if (!$uses_source_ports && !$uses_services) {
+		push(@protocols, $$hash{$key}[8]);
+
+	# Rules which either use ports or services.
+	} elsif ($uses_source_ports || $uses_services) {
+		# Check if service group or service
+		if ($$hash{$key}[14] eq 'cust_srv') {
+			push(@protocols, &fwlib::get_srv_prot($$hash{$key}[15]));
+
+		} elsif($$hash{$key}[14] eq 'cust_srvgrp'){
+			my $protos = &fwlib::get_srvgrp_prot($$hash{$key}[15]);
+			push(@protocols, split(",", $protos));
+
+		} else {
+			# Fetch the protocol for this rule.
+			my $protocol = lc($$hash{$key}[8]);
+
+			# Fetch source and destination ports for this rule.
+			my $source_ports = $$hash{$key}[10];
+			my $destination_ports = $$hash{$key}[15];
+
+			# Check if ports are set for protocols which do not support ports.
+			if (!($protocol ~~ @PROTOCOLS_WITH_PORTS) && ($source_ports || $destination_ports)) {
+				print_error("$protocol does not support ports");
+				return ();
+			}
+
+			push(@protocols, $protocol);
 		}
 	}
-	#DNAT
-	if ($SRC_TGT eq '' && $$hash{$key}[31] eq 'dnat' && $$hash{$key}[11] eq '' && $$hash{$key}[12] ne ''){
-		return "$$hash{$key}[8]";
+
+	# Remove all empty elements
+	@protocols = map { $_ ? $_ : () } @protocols;
+
+	# If no protocol has been defined, we assume "all".
+	if (!@protocols) {
+		push(@protocols, "all");
 	}
+
+	# Make all protocol names lowercase.
+	@protocols = map { lc } @protocols;
+
+	return @protocols;
 }
 
-sub get_port {
-	my $hash=shift;
-	my $key=shift;
-	my $prot=shift;
-	#Get manual defined Ports from SOURCE
-	if ($$hash{$key}[7] eq 'ON' && $SRC_TGT eq 'SRC'){
-		if ($$hash{$key}[10] ne ''){
-			$$hash{$key}[10] =~ s/\|/,/g;
-			if(index($$hash{$key}[10],",") > 0){
-				return "-m multiport --sport $$hash{$key}[10] ";
-			}else{
-				if($$hash{$key}[28] ne 'ON' || ($$hash{$key}[28] eq 'ON' && $$hash{$key}[31] eq 'snat') ||($$hash{$key}[28] eq 'ON' && $$hash{$key}[31] eq 'dnat')  ){
-					return "--sport $$hash{$key}[10] ";
-				}else{
-					return ":$$hash{$key}[10]";
-				}
-			}
+sub get_protocol_options {
+	my $hash = shift;
+	my $key  = shift;
+	my $protocol = shift;
+	my @options = ();
+
+	# Process source ports.
+	my $use_src_ports = ($$hash{$key}[7] eq "ON");
+	my $src_ports     = $$hash{$key}[10];
+
+	if ($use_src_ports && $src_ports) {
+		push(@options, &format_ports($src_ports, "src"));
+	}
+
+	# Process destination ports.
+	my $use_dst_ports  = ($$hash{$key}[11] eq "ON");
+	my $use_dnat       = (($$hash{$key}[28] eq "ON") && ($$hash{$key}[31] eq "dnat"));
+
+	if ($use_dst_ports) {
+		my $dst_ports_mode = $$hash{$key}[14];
+		my $dst_ports      = $$hash{$key}[15];
+		if ($use_dnat && $$hash{$key}[30]) {
+			$dst_ports = $$hash{$key}[30];
 		}
-		#Get manual ports from TARGET
-	}elsif($$hash{$key}[11] eq 'ON' && $SRC_TGT eq ''){
-		if($$hash{$key}[14] eq 'TGT_PORT'){
-			if ($$hash{$key}[15] ne ''){
-				$$hash{$key}[15] =~ s/\|/,/g;
-				if(index($$hash{$key}[15],",") > 0){
-					return "-m multiport --dport $$hash{$key}[15] ";
-				}else{
-					if($$hash{$key}[28] ne 'ON' || ($$hash{$key}[28] eq 'ON' && $$hash{$key}[31] eq 'snat') ){
-						return "--dport $$hash{$key}[15] ";
-					 }else{
-						 $$hash{$key}[15] =~ s/\:/-/g;
-						 return ":$$hash{$key}[15]";
-					 }
-				}
-			}
-		#Get ports defined in custom Service (firewall-groups)
-		}elsif($$hash{$key}[14] eq 'cust_srv'){
-			if ($prot ne 'ICMP'){
-				if($$hash{$key}[31] eq 'dnat' && $$hash{$key}[28] eq 'ON'){
-					my $ports =&fwlib::get_srv_port($$hash{$key}[15],1,$prot);
-					$ports =~ s/\:/-/g;
-					return ":".$ports
-				}else{
-					return "--dport ".&fwlib::get_srv_port($$hash{$key}[15],1,$prot);
-				}
-			}elsif($prot eq 'ICMP' && $$hash{$key}[11] eq 'ON'){        #When PROT is ICMP and "use targetport is checked, this is an icmp-service
-				return "--icmp-type ".&fwlib::get_srv_port($$hash{$key}[15],3,$prot);
-			}
-		#Get ports from services which are used in custom servicegroups (firewall-groups)
-		}elsif($$hash{$key}[14] eq 'cust_srvgrp'){
-			if 	($prot ne 'ICMP'){
-				return &fwlib::get_srvgrp_port($$hash{$key}[15],$prot);
-			}
-			elsif($prot eq 'ICMP'){
-				return &fwlib::get_srvgrp_port($$hash{$key}[15],$prot);
+
+		if (($dst_ports_mode eq "TGT_PORT") && $dst_ports) {
+			push(@options, &format_ports($dst_ports, "dst"));
+
+		} elsif ($dst_ports_mode eq "cust_srv") {
+			if ($protocol eq "ICMP") {
+				push(@options, ("--icmp-type", &fwlib::get_srv_port($dst_ports, 3, "ICMP")));
+			} else {
+				$dst_ports = &fwlib::get_srv_port($dst_ports, 1, uc($protocol));
+				push(@options, &format_ports($dst_ports, "dst"));
 			}
+
+		} elsif ($dst_ports_mode eq "cust_srvgrp") {
+			push(@options, &fwlib::get_srvgrp_port($dst_ports, uc($protocol)));
 		}
 	}
-	#CHECK ICMP
-	if ($$hash{$key}[7] ne 'ON' && $$hash{$key}[11] ne 'ON' && $SRC_TGT eq ''){
-		if($$hash{$key}[9] ne '' && $$hash{$key}[9] ne 'All ICMP-Types'){
-			return "--icmp-type $$hash{$key}[9] ";
-		}elsif($$hash{$key}[9] eq 'All ICMP-Types'){
-			return;
+
+	# Check if a single ICMP type is selected.
+	if (!$use_src_ports && !$use_dst_ports && $protocol eq "icmp") {
+		my $icmp_type = $$hash{$key}[9];
+
+		if (($icmp_type ne "All ICMP-Types") && $icmp_type) {
+			push(@options, ("--icmp-type", $icmp_type));
 		}
 	}
+
+	return @options;
+}
+
+sub format_ports {
+	my $ports = shift;
+	my $type = shift;
+
+	my $arg;
+	if ($type eq "src") {
+		$arg = "--sport";
+	} elsif ($type eq "dst") {
+		$arg = "--dport";
+	}
+
+	my @options = ();
+
+	if ($ports =~ /\|/) {
+		$ports =~ s/\|/,/g;
+		push(@options, ("-m", "multiport"));
+	}
+
+	push(@options, ($arg, $ports));
+
+	return @options;
+}
+
+sub get_dnat_target_port {
+	my $hash = shift;
+	my $key  = shift;
+
+	if ($$hash{$key}[14] eq "TGT_PORT") {
+		return $$hash{$key}[15];
+	}
 }