config/firewall/rules.pl

   1 #!/usr/bin/perl -w
   2 ###############################################################################
   3 #                                                                             #
   4 # IPFire.org - A linux based firewall                                         #
   5 # Copyright (C) 2013 Alexander Marx <amarx@ipfire.org>                        #
   6 #                                                                             #
   7 # This program is free software: you can redistribute it and/or modify        #
   8 # it under the terms of the GNU General Public License as published by        #
   9 # the Free Software Foundation, either version 3 of the License, or           #
  10 # (at your option) any later version.                                         #
  11 #                                                                             #
  12 # This program is distributed in the hope that it will be useful,             #
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of              #
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               #
  15 # GNU General Public License for more details.                                #
  16 #                                                                             #
  17 # You should have received a copy of the GNU General Public License           #
  18 # along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
  19 #                                                                             #
  20 ###############################################################################
  21
  22 use strict;
  23
  24 require '/var/ipfire/general-functions.pl';
  25 require "${General::swroot}/lang.pl";
  26 require "/usr/lib/firewall/firewall-lib.pl";
  27
  28 # Set to one to enable debugging mode.
  29 my $DEBUG = 0;
  30
  31 my $IPTABLES = "iptables --wait";
  32
  33 # iptables chains
  34 my $CHAIN_INPUT           = "INPUTFW";
  35 my $CHAIN_FORWARD         = "FORWARDFW";
  36 my $CHAIN_OUTPUT          = "OUTGOINGFW";
  37 my $CHAIN                 = $CHAIN_FORWARD;
  38 my $CHAIN_NAT_SOURCE      = "NAT_SOURCE";
  39 my $CHAIN_NAT_DESTINATION = "NAT_DESTINATION";
  40 my $CHAIN_MANGLE_NAT_DESTINATION_FIX = "NAT_DESTINATION";
  41 my @VALID_CHAINS          = ($CHAIN_INPUT, $CHAIN_FORWARD, $CHAIN_OUTPUT);
  42 my @ANY_ADDRESSES         = ("0.0.0.0/0.0.0.0", "0.0.0.0/0", "0/0");
  43
  44 my @PROTOCOLS = ("tcp", "udp", "icmp", "igmp", "ah", "esp", "gre", "ipv6", "ipip");
  45 my @PROTOCOLS_WITH_PORTS = ("tcp", "udp");
  46
  47 my @VALID_TARGETS = ("ACCEPT", "DROP", "REJECT");
  48
  49 my %fwdfwsettings=();
  50 my %defaultNetworks=();
  51 my %configfwdfw=();;
  52 my %customgrp=();
  53 my %configinputfw=();
  54 my %configoutgoingfw=();
  55 my %confignatfw=();
  56 my %aliases=();
  57 my @p2ps=();
  58
  59 my $configfwdfw         = "${General::swroot}/firewall/config";
  60 my $configinput     = "${General::swroot}/firewall/input";
  61 my $configoutgoing  = "${General::swroot}/firewall/outgoing";
  62 my $p2pfile                     = "${General::swroot}/firewall/p2protocols";
  63 my $configgrp           = "${General::swroot}/fwhosts/customgroups";
  64 my $netsettings         = "${General::swroot}/ethernet/settings";
  65
  66 &General::readhash("${General::swroot}/firewall/settings", \%fwdfwsettings);
  67 &General::readhash("$netsettings", \%defaultNetworks);
  68 &General::readhasharray($configfwdfw, \%configfwdfw);
  69 &General::readhasharray($configinput, \%configinputfw);
  70 &General::readhasharray($configoutgoing, \%configoutgoingfw);
  71 &General::readhasharray($configgrp, \%customgrp);
  72 &General::get_aliases(\%aliases);
  73
  74 my @log_limit_options = &make_log_limit_options();
  75
  76 # MAIN
  77 &main();
  78
  79 sub main {
  80         # Flush all chains.
  81         &flush();
  82
  83         # Reload firewall rules.
  84         &preparerules();
  85
  86         # Load P2P block rules.
  87         &p2pblock();
  88
  89         # Reload firewall policy.
  90         run("/usr/sbin/firewall-policy");
  91 }
  92
  93 sub run {
  94         # Executes or prints the given shell command.
  95         my $command = shift;
  96
  97         if ($DEBUG) {
  98                 print "$command\n";
  99         } else {
 100                 system "$command";
 101
 102                 if ($?) {
 103                         print_error("ERROR: $command");
 104                 }
 105         }
 106 }
 107
 108 sub print_error {
 109         my $message = shift;
 110
 111         print STDERR "$message\n";
 112 }
 113
 114 sub print_rule {
 115         my $hash = shift;
 116
 117         print "\nRULE:";
 118
 119         my $i = 0;
 120         foreach (@$hash) {
 121                 printf("  %2d: %s", $i++, $_);
 122         }
 123         print "\n";
 124 }
 125
 126 sub flush {
 127         run("$IPTABLES -F $CHAIN_INPUT");
 128         run("$IPTABLES -F $CHAIN_FORWARD");
 129         run("$IPTABLES -F $CHAIN_OUTPUT");
 130         run("$IPTABLES -t nat -F $CHAIN_NAT_SOURCE");
 131         run("$IPTABLES -t nat -F $CHAIN_NAT_DESTINATION");
 132         run("$IPTABLES -t mangle -F $CHAIN_MANGLE_NAT_DESTINATION_FIX");
 133 }
 134
 135 sub preparerules {
 136         if (! -z  "${General::swroot}/firewall/config"){
 137                 &buildrules(\%configfwdfw);
 138         }
 139         if (! -z  "${General::swroot}/firewall/input"){
 140                 &buildrules(\%configinputfw);
 141         }
 142         if (! -z  "${General::swroot}/firewall/outgoing"){
 143                 &buildrules(\%configoutgoingfw);
 144         }
 145 }
 146
 147 sub buildrules {
 148         my $hash = shift;
 149
 150         foreach my $key (sort {$a <=> $b} keys %$hash) {
 151                 # Skip disabled rules.
 152                 next unless ($$hash{$key}[2] eq 'ON');
 153
 154                 if ($DEBUG) {
 155                         print_rule($$hash{$key});
 156                 }
 157
 158                 # Check if the target is valid.
 159                 my $target = $$hash{$key}[0];
 160                 if (!$target ~~ @VALID_TARGETS) {
 161                         print_error("Invalid target '$target' for rule $key");
 162                         next;
 163                 }
 164
 165                 # Check if the chain is valid.
 166                 my $chain = $$hash{$key}[1];
 167                 if (!$chain ~~ @VALID_CHAINS) {
 168                         print_error("Invalid chain '$chain' in rule $key");
 169                         next;
 170                 }
 171
 172                 # Collect all sources.
 173                 my @sources = &fwlib::get_addresses($hash, $key, "src");
 174
 175                 # Collect all destinations.
 176                 my @destinations = &fwlib::get_addresses($hash, $key, "tgt");
 177
 178                 # True if the destination is the firewall itself.
 179                 my $destination_is_firewall = ($$hash{$key}[5] eq "ipfire");
 180
 181                 # Check if logging should be enabled.
 182                 my $LOG = ($$hash{$key}[17] eq 'ON');
 183
 184                 # Check if NAT is enabled and initialize variables, that we use for that.
 185                 my $NAT = ($$hash{$key}[28] eq 'ON');
 186                 my $NAT_MODE;
 187                 if ($NAT) {
 188                         $NAT_MODE = uc($$hash{$key}[31]);
 189                 }
 190
 191                 # Set up time constraints.
 192                 my @time_options = ();
 193                 if ($$hash{$key}[18] eq 'ON') {
 194                         push(@time_options, ("-m", "time"));
 195
 196                         # Select all days of the week this match is active.
 197                         my @weekdays = ();
 198                         if ($$hash{$key}[19] ne '') {
 199                                 push (@weekdays, "Mon");
 200                         }
 201                         if ($$hash{$key}[20] ne '') {
 202                                 push (@weekdays, "Tue");
 203                         }
 204                         if ($$hash{$key}[21] ne '') {
 205                                 push (@weekdays, "Wed");
 206                         }
 207                         if ($$hash{$key}[22] ne '') {
 208                                 push (@weekdays, "Thu");
 209                         }
 210                         if ($$hash{$key}[23] ne '') {
 211                                 push (@weekdays, "Fri");
 212                         }
 213                         if ($$hash{$key}[24] ne '') {
 214                                 push (@weekdays, "Sat");
 215                         }
 216                         if ($$hash{$key}[25] ne '') {
 217                                 push (@weekdays, "Sun");
 218                         }
 219                         if (@weekdays) {
 220                                 push(@time_options, ("--weekdays", join(",", @weekdays)));
 221                         }
 222
 223                         # Convert start time.
 224                         my $time_start = &format_time($$hash{$key}[26]);
 225                         if ($time_start) {
 226                                 push(@time_options, ("--timestart", $time_start));
 227                         }
 228
 229                         # Convert end time.
 230                         my $time_stop = &format_time($$hash{$key}[27]);
 231                         if ($time_stop) {
 232                                 push(@time_options, ("--timestop", $time_stop));
 233                         }
 234                 }
 235
 236                 # Check which protocols are used in this rule and so that we can
 237                 # later group rules by protocols.
 238                 my @protocols = &get_protocols($hash, $key);
 239                 if (!@protocols) {
 240                         print_error("Invalid protocol configuration for rule $key");
 241                         next;
 242                 }
 243
 244                 foreach my $protocol (@protocols) {
 245                         # Check if the given protocol is supported.
 246                         if (($protocol ne "all") && (!$protocol ~~ @PROTOCOLS)) {
 247                                 print_error("Protocol $protocol is not supported (rule $key)");
 248                                 next;
 249                         }
 250
 251                         # Prepare protocol options (like ICMP types, ports, etc...).
 252                         my @protocol_options = &get_protocol_options($hash, $key, $protocol, 0);
 253
 254                         # Check if this protocol knows ports.
 255                         my $protocol_has_ports = ($protocol ~~ @PROTOCOLS_WITH_PORTS);
 256
 257                         foreach my $source (@sources) {
 258                                 foreach my $destination (@destinations) {
 259                                         # Skip invalid rules.
 260                                         next if (!$source || !$destination || ($destination eq "none"));
 261
 262                                         # Sanitize source.
 263                                         if ($source ~~ @ANY_ADDRESSES) {
 264                                                 $source = "";
 265                                         }
 266
 267                                         # Sanitize destination.
 268                                         if ($destination ~~ @ANY_ADDRESSES) {
 269                                                 $destination = "";
 270                                         }
 271
 272                                         # Array with iptables arguments.
 273                                         my @options = ();
 274
 275                                         # Append protocol.
 276                                         if ($protocol ne "all") {
 277                                                 push(@options, @protocol_options);
 278                                         }
 279
 280                                         # Prepare source options.
 281                                         my @source_options = ();
 282                                         if ($source =~ /mac/) {
 283                                                 push(@source_options, $source);
 284                                         } elsif ($source) {
 285                                                 push(@source_options, ("-s", $source));
 286                                         }
 287
 288                                         # Prepare destination options.
 289                                         my @destination_options = ();
 290                                         if ($destination) {
 291                                                 push(@destination_options, ("-d", $destination));
 292                                         }
 293
 294                                         # Add time constraint options.
 295                                         push(@options, @time_options);
 296
 297                                         my $firewall_is_in_source_subnet = 0;
 298                                         if ($source) {
 299                                                 $firewall_is_in_source_subnet = &firewall_is_in_subnet($source);
 300                                         }
 301
 302                                         # Process NAT rules.
 303                                         if ($NAT) {
 304                                                 my $nat_address = &fwlib::get_nat_address($$hash{$key}[29], $source);
 305
 306                                                 # Skip NAT rules if the NAT address is unknown
 307                                                 # (i.e. no internet connection has been established, yet).
 308                                                 next unless ($nat_address);
 309
 310                                                 # Destination NAT
 311                                                 if ($NAT_MODE eq "DNAT") {
 312                                                         # Make port-forwardings useable from the internal networks.
 313                                                         my @internal_addresses = &fwlib::get_internal_firewall_ip_addresses(1);
 314                                                         unless ($nat_address ~~ @internal_addresses) {
 315                                                                 &add_dnat_mangle_rules($nat_address, @options);
 316                                                         }
 317
 318                                                         my @nat_options = ();
 319                                                         if ($protocol ne "all") {
 320                                                                 my @nat_protocol_options = &get_protocol_options($hash, $key, $protocol, 1);
 321                                                                 push(@nat_options, @nat_protocol_options);
 322                                                         }
 323                                                         push(@nat_options, @source_options);
 324                                                         push(@nat_options, ("-d", $nat_address));
 325
 326                                                         my $dnat_port;
 327                                                         if ($protocol_has_ports) {
 328                                                                 $dnat_port = &get_dnat_target_port($hash, $key);
 329                                                         }
 330
 331                                                         my @nat_action_options = ();
 332
 333                                                         # Use iptables REDIRECT
 334                                                         my $use_redirect = ($destination_is_firewall && !$destination && $protocol_has_ports && $dnat_port);
 335                                                         if ($use_redirect) {
 336                                                                 push(@nat_action_options, ("-j", "REDIRECT", "--to-ports", $dnat_port));
 337
 338                                                         # Use iptables DNAT
 339                                                         } else {
 340                                                                 my ($dnat_address, $dnat_mask) = split("/", $destination);
 341                                                                 @destination_options = ("-d", $dnat_address);
 342
 343                                                                 if ($protocol_has_ports) {
 344                                                                         my $dnat_port = &get_dnat_target_port($hash, $key);
 345
 346                                                                         if ($dnat_port) {
 347                                                                                 $dnat_address .= ":$dnat_port";
 348                                                                         }
 349                                                                 }
 350
 351                                                                 push(@nat_action_options, ("-j", "DNAT", "--to-destination", $dnat_address));
 352                                                         }
 353
 354                                                         if ($LOG) {
 355                                                                 run("$IPTABLES -t nat -A $CHAIN_NAT_DESTINATION @nat_options @log_limit_options -j LOG --log-prefix 'DNAT '");
 356                                                         }
 357                                                         run("$IPTABLES -t nat -A $CHAIN_NAT_DESTINATION @nat_options @nat_action_options");
 358
 359                                                 # Source NAT
 360                                                 } elsif ($NAT_MODE eq "SNAT") {
 361                                                         my @nat_options = @options;
 362
 363                                                         push(@nat_options, @source_options);
 364                                                         push(@nat_options, @destination_options);
 365
 366                                                         if ($LOG) {
 367                                                                 run("$IPTABLES -t nat -A $CHAIN_NAT_SOURCE @nat_options @log_limit_options -j LOG --log-prefix 'SNAT '");
 368                                                         }
 369                                                         run("$IPTABLES -t nat -A $CHAIN_NAT_SOURCE @nat_options -j SNAT --to-source $nat_address");
 370                                                 }
 371                                         }
 372
 373                                         push(@options, @source_options);
 374
 375                                         if ($firewall_is_in_source_subnet && ($fwdfwsettings{"POLICY"} eq "MODE1") && ($chain eq $CHAIN_FORWARD)) {
 376                                                 if ($LOG && !$NAT) {
 377                                                         run("$IPTABLES -A $CHAIN_INPUT @options @log_limit_options -j LOG --log-prefix '$CHAIN_INPUT '");
 378                                                 }
 379                                                 run("$IPTABLES -A $CHAIN_INPUT @options -j $target");
 380                                         }
 381
 382                                         push(@options, @destination_options);
 383
 384                                         # Insert firewall rule.
 385                                         if ($LOG && !$NAT) {
 386                                                 run("$IPTABLES -A $chain @options @log_limit_options -j LOG --log-prefix '$chain '");
 387                                         }
 388                                         run("$IPTABLES -A $chain @options -j $target");
 389                                 }
 390                         }
 391                 }
 392         }
 393 }
 394
 395 # Formats the given timestamp into the iptables format which is "hh:mm" UTC.
 396 sub format_time {
 397         my $val = shift;
 398
 399         # Convert the given time into minutes.
 400         my $minutes = &time_convert_to_minutes($val);
 401
 402         # Move the timestamp into UTC.
 403         $minutes += &time_utc_offset();
 404
 405         # Make sure $minutes is between 00:00 and 23:59.
 406         if ($minutes < 0) {
 407                 $minutes += 1440;
 408         }
 409
 410         if ($minutes > 1440) {
 411                 $minutes -= 1440;
 412         }
 413
 414         # Format as hh:mm.
 415         return sprintf("%02d:%02d", $minutes / 60, $minutes % 60);
 416 }
 417
 418 # Calculates the offsets in minutes from the local timezone to UTC.
 419 sub time_utc_offset {
 420         my @localtime = localtime(time);
 421         my @gmtime = gmtime(time);
 422
 423         return ($gmtime[2] * 60 + $gmtime[1] % 60) - ($localtime[2] * 60 + $localtime[1] % 60);
 424 }
 425
 426 # Takes a timestamp like "14:00" and converts it into minutes since midnight.
 427 sub time_convert_to_minutes {
 428         my ($hrs, $min) = split(":", shift);
 429
 430         return ($hrs * 60) + $min;
 431 }
 432
 433 sub p2pblock {
 434         my $P2PSTRING = "";
 435         my $DO;
 436         open( FILE, "< $p2pfile" ) or die "Unable to read $p2pfile";
 437         @p2ps = <FILE>;
 438         close FILE;
 439         my $CMD = "-m ipp2p";
 440         foreach my $p2pentry (sort @p2ps) {
 441                 my @p2pline = split( /\;/, $p2pentry );
 442                 if ( $fwdfwsettings{'POLICY'} eq 'MODE1' ) {
 443                         $DO = "ACCEPT";
 444                         if ("$p2pline[2]" eq "on") {
 445                                 $P2PSTRING = "$P2PSTRING --$p2pline[1]";
 446                         }
 447                 }else {
 448                         $DO = "RETURN";
 449                         if ("$p2pline[2]" eq "off") {
 450                                 $P2PSTRING = "$P2PSTRING --$p2pline[1]";
 451                         }
 452                 }
 453         }
 454
 455         if($P2PSTRING) {
 456                 run("$IPTABLES -A FORWARDFW $CMD $P2PSTRING -j $DO");
 457         }
 458 }
 459
 460 sub get_protocols {
 461         my $hash = shift;
 462         my $key = shift;
 463
 464         my $uses_source_ports = ($$hash{$key}[7] eq "ON");
 465         my $uses_services = ($$hash{$key}[11] eq "ON");
 466
 467         my @protocols = ();
 468
 469         # Rules which don't have source ports or services (like ICMP, ESP, ...).
 470         if (!$uses_source_ports && !$uses_services) {
 471                 push(@protocols, $$hash{$key}[8]);
 472
 473         # Rules which either use ports or services.
 474         } elsif ($uses_source_ports || $uses_services) {
 475                 # Check if service group or service
 476                 if ($$hash{$key}[14] eq 'cust_srv') {
 477                         push(@protocols, &fwlib::get_srv_prot($$hash{$key}[15]));
 478
 479                 } elsif($$hash{$key}[14] eq 'cust_srvgrp'){
 480                         my $protos = &fwlib::get_srvgrp_prot($$hash{$key}[15]);
 481                         push(@protocols, split(",", $protos));
 482
 483                 } else {
 484                         # Fetch the protocol for this rule.
 485                         my $protocol = lc($$hash{$key}[8]);
 486
 487                         # Fetch source and destination ports for this rule.
 488                         my $source_ports = $$hash{$key}[10];
 489                         my $destination_ports = $$hash{$key}[15];
 490
 491                         # Check if ports are set for protocols which do not support ports.
 492                         if (!($protocol ~~ @PROTOCOLS_WITH_PORTS) && ($source_ports || $destination_ports)) {
 493                                 print_error("$protocol does not support ports");
 494                                 return ();
 495                         }
 496
 497                         push(@protocols, $protocol);
 498                 }
 499         }
 500
 501         # Remove all empty elements
 502         @protocols = map { $_ ? $_ : () } @protocols;
 503
 504         # If no protocol has been defined, we assume "all".
 505         if (!@protocols) {
 506                 push(@protocols, "all");
 507         }
 508
 509         # Make all protocol names lowercase.
 510         @protocols = map { lc } @protocols;
 511
 512         return @protocols;
 513 }
 514
 515 sub get_protocol_options {
 516         my $hash = shift;
 517         my $key  = shift;
 518         my $protocol = shift;
 519         my $nat_options_wanted = shift;
 520         my @options = ();
 521
 522         # Nothing to do if no protocol is specified.
 523         if ($protocol eq "all") {
 524                 return @options;
 525         } else {
 526                 push(@options, ("-p", $protocol));
 527         }
 528
 529         # Process source ports.
 530         my $use_src_ports = ($$hash{$key}[7] eq "ON");
 531         my $src_ports     = $$hash{$key}[10];
 532
 533         if ($use_src_ports && $src_ports) {
 534                 push(@options, &format_ports($src_ports, "src"));
 535         }
 536
 537         # Process destination ports.
 538         my $use_dst_ports  = ($$hash{$key}[11] eq "ON");
 539         my $use_dnat       = (($$hash{$key}[28] eq "ON") && ($$hash{$key}[31] eq "dnat"));
 540
 541         if ($use_dst_ports) {
 542                 my $dst_ports_mode = $$hash{$key}[14];
 543                 my $dst_ports      = $$hash{$key}[15];
 544
 545                 if (($dst_ports_mode eq "TGT_PORT") && $dst_ports) {
 546                         if ($nat_options_wanted && $use_dnat && $$hash{$key}[30]) {
 547                                 $dst_ports = $$hash{$key}[30];
 548                         }
 549                         push(@options, &format_ports($dst_ports, "dst"));
 550
 551                 } elsif ($dst_ports_mode eq "cust_srv") {
 552                         if ($protocol eq "ICMP") {
 553                                 push(@options, ("--icmp-type", &fwlib::get_srv_port($dst_ports, 3, "ICMP")));
 554                         } else {
 555                                 $dst_ports = &fwlib::get_srv_port($dst_ports, 1, uc($protocol));
 556                                 push(@options, &format_ports($dst_ports, "dst"));
 557                         }
 558
 559                 } elsif ($dst_ports_mode eq "cust_srvgrp") {
 560                         push(@options, &fwlib::get_srvgrp_port($dst_ports, uc($protocol)));
 561                 }
 562         }
 563
 564         # Check if a single ICMP type is selected.
 565         if (!$use_src_ports && !$use_dst_ports && $protocol eq "icmp") {
 566                 my $icmp_type = $$hash{$key}[9];
 567
 568                 if (($icmp_type ne "All ICMP-Types") && $icmp_type) {
 569                         push(@options, ("--icmp-type", $icmp_type));
 570                 }
 571         }
 572
 573         return @options;
 574 }
 575
 576 sub format_ports {
 577         my $ports = shift;
 578         my $type = shift;
 579
 580         my $arg;
 581         if ($type eq "src") {
 582                 $arg = "--sport";
 583         } elsif ($type eq "dst") {
 584                 $arg = "--dport";
 585         }
 586
 587         my @options = ();
 588
 589         if ($ports =~ /\|/) {
 590                 $ports =~ s/\|/,/g;
 591                 push(@options, ("-m", "multiport"));
 592         }
 593
 594         if ($ports) {
 595                 push(@options, ($arg, $ports));
 596         }
 597
 598         return @options;
 599 }
 600
 601 sub get_dnat_target_port {
 602         my $hash = shift;
 603         my $key  = shift;
 604
 605         if ($$hash{$key}[14] eq "TGT_PORT") {
 606                 my $port = $$hash{$key}[15];
 607                 my $external_port = $$hash{$key}[30];
 608
 609                 if ($external_port && ($port ne $external_port)) {
 610                         return $$hash{$key}[15];
 611                 }
 612         }
 613 }
 614
 615 sub add_dnat_mangle_rules {
 616         my $nat_address = shift;
 617         my @options = @_;
 618
 619         my $mark = 0;
 620         foreach my $zone ("GREEN", "BLUE", "ORANGE") {
 621                 $mark++;
 622
 623                 # Skip rule if not all required information exists.
 624                 next unless (exists $defaultNetworks{$zone . "_NETADDRESS"});
 625                 next unless (exists $defaultNetworks{$zone . "_NETMASK"});
 626
 627                 my @mangle_options = @options;
 628
 629                 my $netaddress = $defaultNetworks{$zone . "_NETADDRESS"};
 630                 $netaddress .= "/" . $defaultNetworks{$zone . "_NETMASK"};
 631
 632                 push(@mangle_options, ("-s", $netaddress, "-d", $nat_address));
 633                 push(@mangle_options, ("-j", "MARK", "--set-mark", $mark));
 634
 635                 run("$IPTABLES -t mangle -A $CHAIN_MANGLE_NAT_DESTINATION_FIX @mangle_options");
 636         }
 637 }
 638
 639 sub make_log_limit_options {
 640         my @options = ("-m", "limit");
 641
 642         # Maybe we should get this from the configuration.
 643         my $limit = 10;
 644
 645         # We limit log messages to $limit messages per minute.
 646         push(@options, ("--limit", "$limit/min"));
 647
 648         # And we allow bursts of 2x $limit.
 649         push(@options, ("--limit-burst", $limit * 2));
 650
 651         return @options;
 652 }
 653
 654 sub firewall_is_in_subnet {
 655         my $subnet = shift;
 656
 657         # ORANGE is missing here, because nothing may ever access
 658         # the firewall from this network.
 659         my $address = &fwlib::get_internal_firewall_ip_address($subnet, 0);
 660
 661         if ($address) {
 662                 return 1;
 663         }
 664
 665         return 0;
 666 }
 667