    DNSBLOG(8)                                                          DNSBLOG(8)

    NAME
           dnsblog - Postfix DNS allow/denylist logger

    SYNOPSIS
           dnsblog [generic Postfix daemon options]

    DESCRIPTION
           The  dnsblog(8)  server  implements an ad-hoc DNS allow/denylist lookup
           service. This may eventually be replaced by an UDP client that is built
           directly into the postscreen(8) server.

    PROTOCOL
           With   each   connection,   the   dnsblog(8)   server  receives  a  DNS
           allow/denylist domain name, an IP  address,  and  an  ID.   If  the  IP
           address  is  listed under the DNS allow/denylist, the dnsblog(8) server
           logs the match and replies with the query  arguments  plus  an  address
           list  with the resulting IP addresses, separated by whitespace, and the
           reply TTL.  Otherwise it replies with the query arguments plus an empty
           address  list  and  the  reply  TTL; the reply TTL is -1 if there is no
           reply, or a negative reply that contains no SOA record.   Finally,  the
           dnsblog(8) server closes the connection.

    DIAGNOSTICS
           Problems and transactions are logged to syslogd(8) or postlogd(8).

    CONFIGURATION PARAMETERS
           Changes to main.cf are picked up automatically, as dnsblog(8) processes
           run for only a limited amount of time. Use the command "postfix reload"
           to speed up a change.

           The  text  below provides only a parameter summary. See postconf(5) for
           more details including examples.

           config_directory (see 'postconf -d' output)
                  The default location of the Postfix main.cf and  master.cf  con-
                  figuration files.

           daemon_timeout (18000s)
                  How  much  time  a  Postfix  daemon process may take to handle a
                  request before it is terminated by a built-in watchdog timer.

           postscreen_dnsbl_sites (empty)
                  Optional list of patterns with DNS allow/denylist domains,  fil-
                  ters and weight factors.

           ipc_timeout (3600s)
                  The  time  limit  for  sending  or receiving information over an
                  internal communication channel.

           process_id (read-only)
                  The process ID of a Postfix command or daemon process.

           process_name (read-only)
                  The process name of a Postfix command or daemon process.

           queue_directory (see 'postconf -d' output)
                  The location of the Postfix top-level queue directory.

           syslog_facility (mail)
                  The syslog facility of Postfix logging.

           syslog_name (see 'postconf -d' output)
                  A prefix that  is  prepended  to  the  process  name  in  syslog
                  records, so that, for example, "smtpd" becomes "prefix/smtpd".

           Available in Postfix 3.3 and later:

           service_name (read-only)
                  The master.cf service name of a Postfix daemon process.

    SEE ALSO
           smtpd(8), Postfix SMTP server
           postconf(5), configuration parameters
           postlogd(8), Postfix logging
           syslogd(8), system logging

    LICENSE
           The Secure Mailer license must be distributed with this software.

    HISTORY
           This service was introduced with Postfix version 2.8.

    AUTHOR(S)
           Wietse Venema
           IBM T.J. Watson Research
           P.O. Box 704
           Yorktown Heights, NY 10598, USA

           Wietse Venema
           Google, Inc.
           111 8th Avenue
           New York, NY 10011, USA

                                                                        DNSBLOG(8)