FILTER-DNSBL(8)

NAME
filter-dnsbl - smtpd filter for DNSBL checks

SYNOPSIS
filter-dnsbl [-h host]

DESCRIPTION
filter-dnsbl is a filter for smtpd(8) which can be used to check new connections against a DNS-based Blackhole List (DNSBL).

The options are as follows:

-h host
    Set the DNSBL host to be queried.

    The default host is dnsbl.sorbs.net.

The remote IP address of new connections is used in a DNS query against the DNSBL. If the remote address is listed, the connection is rejected, otherwise accepted.

SEE ALSO
filter_api(3), smtpd.conf(5), smtpd(8)

HISTORY
The first version of filter-dnsbl was written in 2013.

AUTHORS
Eric Faurot <eric@openbsd.org>