anvil [generic Postfix daemon options]

In the following text, ident specifies a (service, client) combination. The exact syntax of that information is application-dependent; the anvil(8) server does not care.  

    request=connect
    ident=string

The anvil(8) server answers with the number of simultaneous connections and the number of connections per unit time for the (service, client) combination specified with ident:

    status=0
    count=number
    rate=number

To register a disconnect event send the following request to the anvil(8) server:

    request=disconnect
    ident=string

The anvil(8) server replies with:

    status=0

    request=message
    ident=string

The anvil(8) server answers with the number of message delivery requests per unit time for the (service, client) combination specified with ident:

    status=0
    rate=number

    request=recipient
    ident=string

The anvil(8) server answers with the number of recipient addresses per unit time for the (service, client) combination specified with ident:

    status=0
    rate=number

To register a request for a new (i.e. not cached) TLS session send the following request to the anvil(8) server:

    request=newtls
    ident=string

The anvil(8) server answers with the number of new TLS session requests per unit time for the (service, client) combination specified with ident:

    status=0
    rate=number

To retrieve new TLS session request rate information without updating the counter information, send:

    request=newtls_report
    ident=string

The anvil(8) server answers with the number of new TLS session requests per unit time for the (service, client) combination specified with ident:

    status=0
    rate=number

The anvil(8) server maintains an in-memory table with information about recent clients requests. No persistent state is kept because standard system library routines are not sufficiently robust for update-intensive applications.

Although the in-memory state is kept only temporarily, this may require a lot of memory on systems that handle connections from many remote clients. To reduce memory usage, reduce the time unit over which state is kept.  

Upon exit, and every anvil_status_update_time seconds, the server logs the maximal count and rate values measured, together with (service, client) information and the time of day associated with those events. In order to avoid unnecessary overhead, no measurements are done for activity that isn't concurrency limited or rate limited.  

In this preliminary implementation, a count (or rate) limited server can have only one remote client at a time. If a server reports multiple simultaneous clients, state is kept only for the last reported client.

The anvil(8) server automatically discards client request information after it expires. To prevent the anvil(8) server from discarding client request rate information too early or too late, a rate limited service should always register connect/disconnect events even when it does not explicitly limit them.  

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

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 (postfix)

The mail system name that is prepended to the process name in syslog records, so that "smtpd" becomes, for example, "postfix/smtpd".

smtpd(8), Postfix SMTP server
postconf(5), configuration parameters
master(5), generic daemon options

TUNING_README, performance tuning

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

NAME

SYNOPSIS

DESCRIPTION

CONNECTION COUNT/RATE CONTROL

MESSAGE RATE CONTROL

RECIPIENT RATE CONTROL

TLS SESSION NEGOTIATION RATE CONTROL

SECURITY

DIAGNOSTICS

BUGS

CONFIGURATION PARAMETERS

SEE ALSO

README FILES

LICENSE

HISTORY

AUTHOR(S)