new plugin: common/require-rdns

[Steve Kemp]

  This is a simple plugin which has helped me out a fair bit.  It 
 ensures that connecting hosts have reverse DNS.  (Though it doesn't
 actually care what rdns is present.)

  I have it setup in this order:

common/hosts_allow
common/require-rdns
common/check_earlytalker

  Comments welcome ..  the only obvious comment is that the action is
 hard-wired, but I could change that if it were useful.

Steve
-- 
http://mail-scanning.com/


#!/usr/bin/perl -w

=head1 NAME

require-rdns - Test that connecting hosts have reverse DNS record(s).

=cut

=head1 DESCRIPTION

  The smtp servers which connect to us should have reverse DNS.  We don't
 care what it is, but it should be there..

=cut


=begin doc

  Called at SMTP-connect time.  Ensure that there is RDNS present,
 otherwise drop.

=end doc

=cut

sub hook_connect
{
    my ($self, $transaction) = @_;
    my $remote_ip = $self->qp->connection->remote_ip;
    my $remote_host = $self->qp->connection->remote_host;

    if ( ($remote_ip eq $remote_host) ||
         ($remote_host eq "Unknown" ) )
    {
        $self->log(LOGWARN, "require-rdns: $remote_ip no RDNS: $remote_host" );
        return (DENY_DISCONNECT, "RDNS lookup for $remote_ip failed 
[$remote_host]");
    }
    else
    {
        return DECLINED;
    }
}