Updated: 2022/Sep/29

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DNSBLOG(8)                  System Manager's Manual                 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
              configuration 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 DNS allow/denylist domains, filters 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



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