|ANVIL(8)||System Manager's Manual||ANVIL(8)|
anvil [generic Postfix daemon options]
The Postfix anvil(8) server maintains statistics about client connection counts or client request rates. This information can be used to defend against clients that hammer a server with either too many simultaneous sessions, or with too many successive requests within a configurable time interval. This server is designed to run under control by the Postfix master(8) server.
To register a new connection send the following request to the anvil(8) server:
status=0 count=number rate=number
To register a message delivery request send the following request to the anvil(8) server:
To register a recipient request send the following request to the anvil(8) server:
The features described in this section are available with Postfix 2.3 and later.
To register an AUTH request send the following request to the anvil(8) server:
The anvil(8) server does not talk to the network or to local users, and can run chrooted at fixed low privilege.
Problems and transactions are logged to syslogd(8).
Systems behind network address translating routers or proxies appear to have the same client address and can run into connection count and/or rate limits falsely.
On low-traffic mail systems, changes to main.cf are picked up automatically as anvil(8) processes run for only a limited amount of time. On other mail systems, use the command " postfix reload" to speed up a change.
- anvil_rate_time_unit (60s)
- The time unit over which client connection rates and other rates are calculated.
- anvil_status_update_time (600s)
- How frequently the anvil(8) connection and rate limiting server logs peak usage information.
- 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.
- ipc_timeout (3600s)
- The time limit for sending or receiving information over an internal communication channel.
- max_idle (100s)
- The maximum amount of time that an idle Postfix daemon process waits for an incoming connection before terminating voluntarily.
- max_use (100)
- The maximal number of incoming connections that a Postfix daemon process will service before terminating voluntarily.
- 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.
- 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".
smtpd(8), Postfix SMTP server postconf(5), configuration parameters master(5), generic daemon options
Use " postconf readme_directory" or " postconf html_directory" to locate this information.
TUNING_README, performance tuning
The Secure Mailer license must be distributed with this software.
The anvil service is available in Postfix 2.2 and later.
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