man Mail::Milter::Module::ConnectMatchesHostname () - milter to accept/reject connecting hosts matching regex(es)

NAME

Mail::Milter::Module::ConnectMatchesHostname - milter to accept/reject connecting hosts matching regex(es)

SYNOPSIS

    use Mail::Milter::Module::ConnectMatchesHostname;


    my $milter = new Mail::Milter::Module::ConnectMatchesHostname;


    my $milter2 = &ConnectMatchesHostname; # convenience


    $milter2->set_message('Connecting hostname %H looks like a dynamic address');

DESCRIPTION

This milter module rejects any connecting host whose hostname contains one of a group of built-in patterns that match the IP address of the connecting host. This is normally used to detect dynamic pool addresses.

Currently the following patterns embedded in the hostname are considered matching, where 10.11.12.13 is the IPv4 address of the connecting host. In the following cases, the string must be preceded by a non-digit character or otherwise must be at the start of the hostname. 

    010.011.012.013. (optionally without internal dots, or with - in place of .)
    013.012.011.010. (optionally with - in place of .)
    10.11.12.13. (optionally without internal dots, or with - in place of .)
    13.12.11.10. (optionally with - in place of .)
    0A0B0C0D (hexadecimal, ignoring case)

More specific patterns are anticipated to be added in the future. Because of this, if you use ConnectMatchesHostname, pay attention to this perldoc manual page when updating to a newer version of Mail::Milter.

One final note. ISPs can and do use dynamic-looking reverse DNS entries for what they consider to be legitimate server addresses. This is not ideal, and may require embedding this module in a Chain set to accept_break with regular expressions; for example: 

    my $milter = new Mail::Milter::Chain(
        &ConnectRegex(
            '\.fooisp\.com$',
        )->accept_match(1);
        &ConnectMatchesHostname,
    )->accept_break(1);

METHODS

new()
Creates a ConnectMatchesHostname object.
set_message(MESSAGE)
Sets the message used when rejecting connections. This string may contain the substring CW%H, which will be replaced by the matching hostname, and/or the substring CW%A, which will be replaced by the matching IP address. This method returns a reference to the object itself, allowing this method call to be chained.

BUGS

In Sendmail 8.11 and 8.12, a milter rejection at connect stage does not allow the reply message to be set it simply becomes not accepting messages. However, this module still attempts to set the reply code and message in the hope that this will be fixed.

The implementation of this module could be much more efficient.

AUTHOR

Todd Vierling, <tv@duh.org> <tv@pobox.com>

SEE ALSO

Mail::Milter::Object