259 lines
6.7 KiB
Perl
259 lines
6.7 KiB
Perl
#!perl -w
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=head1 SYNOPSIS
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relay - control whether relaying is permitted
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=head1 DESCRIPTION
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relay - check the following places to see if relaying is allowed:
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I<$ENV{RELAYCLIENT}>
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I<config/norelayclients>, I<config/relayclients>, I<config/morerelayclients>
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The search order is as shown and cascades until a match is found or the list
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is exhausted.
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Note that I<norelayclients> is the first file checked. A match there will
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override matches in the subsequent files.
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=head1 CONFIG
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Enable this plugin by adding it to config/plugins above the rcpt_* plugins
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# other plugins...
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relay
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# rcpt_* go here
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=head2 relayclients
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A list of IP addresses that are permitted to relay mail through this server.
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Each line in I<relayclients> is one of:
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- a full IP address
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- partial IP address terminated by a dot or colon for matching whole networks
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192.168.42.
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2001:db8:e431:ae06:
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...
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- a network/mask, aka a CIDR block
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10.1.0.0/24
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2001:db8:e431:ae06::/64
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...
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=head2 morerelayclients
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Additional IP addresses that are permitted to relay. The syntax of the config
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file is identical to I<relayclients> except that CIDR (net/mask) entries are
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not supported. If you have many (>50) IPs allowed to relay, most should likely
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be listed in I<morerelayclients> where lookups are faster.
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=head2 norelayclients
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I<norelayclients> allows specific clients, such as a mail gateway, to be denied
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relaying, even though they would be allowed by I<relayclients>. This is most
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useful when a block of IPs is allowed in relayclients, but several IPs need to
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be excluded.
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The file format is the same as morerelayclients.
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=head2 RELAY ONLY
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The relay only option restricts connections to only clients that have relay
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permission. All other connections are denied during the RCPT phase of the
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SMTP conversation.
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This option is useful when a server is used as the smart relay host for
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internal users and external/authenticated users, but should not be considered
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a normal inbound MX server.
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It should be configured to be run before other RCPT hooks! Only clients that
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have authenticated or are listed in the relayclient file will be allowed to
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send mail.
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To enable relay only mode, set the B<only> option to any true value in
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I<config/plugins> as shown:
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relay only 1
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=head1 AUTHOR
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2012 - Matt Simerson - Merged check_relay, check_norelay, and relayonly
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2006 - relay_only - John Peackock
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2005 - check_norelay - Copyright Gordon Rowell <gordonr@gormand.com.au>
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2002 - check_relay - Ask Bjorn Hansen
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=head1 LICENSE
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This software is free software and may be distributed under the same
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terms as qpsmtpd itself.
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=cut
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use strict;
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use warnings;
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use Qpsmtpd::Constants;
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use Net::IP qw(:PROC);
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sub register {
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my ($self, $qp) = (shift, shift);
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$self->log(LOGERROR, "Bad arguments") if @_ % 2;
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$self->{_args} = {@_};
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if ($self->{_args}{only}) {
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$self->register_hook('rcpt', 'relay_only');
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}
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}
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sub is_in_norelayclients {
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my $self = shift;
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my %no_relay_clients = map { $_ => 1 } $self->qp->config('norelayclients');
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my $ip = $self->qp->connection->remote_ip;
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while ($ip) {
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if (exists $no_relay_clients{$ip}) {
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$self->log(LOGINFO, "$ip in norelayclients");
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return 1;
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}
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$ip =~ s/(\d|\w)+(:|\.)?$// or last; # strip off another octet
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}
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$self->log(LOGDEBUG, "no match in norelayclients");
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return;
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}
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sub populate_relayclients {
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my $self = shift;
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foreach ($self->qp->config('relayclients')) {
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my ($network, $netmask) = ip_splitprefix($_);
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if ($netmask) {
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push @{$self->{_cidr_blocks}}, $_;
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next;
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}
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$self->{_octets}{$_} = 1; # no prefix, split
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}
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}
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sub is_in_cidr_block {
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my $self = shift;
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my $ip = $self->qp->connection->remote_ip or do {
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$self->log(LOGINFO, "err, no remote_ip?");
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return;
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};
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my $cversion = ip_get_version($ip);
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for (@{$self->{_cidr_blocks}}) {
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my ($network, $mask) = ip_splitprefix($_); # split IP & CIDR range
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my $rversion = ip_get_version($network); # get IP version (4 vs 6)
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my ($begin, $end) = ip_normalize($_, $rversion); # get pool start/end
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# expand the client address (zero pad it) before converting to binary
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my $bin_ip = ip_iptobin(ip_expand_address($ip, $cversion), $cversion)
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or next;
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next if !$begin || !$end; # probably not a netmask entry
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if ( ip_bincomp($bin_ip, 'gt', ip_iptobin($begin, $rversion))
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&& ip_bincomp($bin_ip, 'lt', ip_iptobin($end, $rversion)))
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{
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$self->log(LOGINFO, "pass, cidr match ($ip)");
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return 1;
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}
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}
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$self->log(LOGDEBUG, "no cidr match");
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return;
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}
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sub is_octet_match {
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my $self = shift;
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my $ip = $self->qp->connection->remote_ip;
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if ($ip eq '::1') {
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$self->log(LOGINFO, "pass, octet matched localhost ($ip)");
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return 1;
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}
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my $more_relay_clients = $self->qp->config('morerelayclients', 'map');
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my $ipv6 = $ip =~ /:/ ? 1 : 0;
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if ($ipv6 && $ip =~ /::/) { # IPv6 compressed notation
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$ip = Net::IP::ip_expand_address($ip, 6);
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}
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while ($ip) {
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if (exists $self->{_octets}{$ip}) {
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$self->log(LOGINFO, "pass, octet match in relayclients ($ip)");
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return 1;
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}
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if (exists $more_relay_clients->{$ip}) {
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$self->log(LOGINFO, "pass, octet match in morerelayclients ($ip)");
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return 1;
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}
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# added IPv6 support (Michael Holzt - 2012-11-14)
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if ($ipv6) {
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$ip =~ s/[0-9a-f]:?$//; # strip off another nibble
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chop $ip if ':' eq substr($ip, -1, 1);
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}
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else {
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$ip =~ s/\d+\.?$// or last; # strip off another 8 bits
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}
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}
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$self->log(LOGDEBUG, "no octet match");
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return;
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}
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sub hook_connect {
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my ($self, $transaction) = @_;
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if ($self->is_in_norelayclients()) {
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$self->qp->connection->relay_client(0);
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delete $ENV{RELAYCLIENT};
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$self->log(LOGINFO, "fail, disabled by norelayclients");
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return DECLINED;
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}
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if (defined $ENV{RELAYCLIENT}) {
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$self->qp->connection->relay_client(1);
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$self->log(LOGINFO, "pass, enabled by env");
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return DECLINED;
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}
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$self->populate_relayclients();
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# 95586 (connect) relay: pass, octet match in relayclients (127.0.0.)
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if ($self->is_in_cidr_block() || $self->is_octet_match()) {
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$self->qp->connection->relay_client(1);
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return DECLINED;
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}
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$self->log(LOGINFO, "skip, no match");
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return DECLINED;
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}
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sub relay_only {
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my $self = shift;
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if ($self->qp->connection->relay_client) {
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return OK;
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}
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return DENY;
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}
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