MIMEDEFANG(8)						      System Manager's Manual						     MIMEDEFANG(8)

NAME

       mimedefang - Sendmail MIME mail filter

SYNOPSIS

       mimedefang prcap

       mimedefang -p connection -m mx_socket_name -U user [options]

DESCRIPTION

       mimedefang  is  a  filter built around Sendmail 8.11's milter API for mail filters.  It collects each incoming message and runs a filter on
       the message.  This is useful for deleting attachments which may be a security risk on poorly-designed systems like Microsoft Windows.

       mimedefang does not actually run the Perl filter; instead, it communicates with mimedefang-multiplexor(8), which manages a pool of  persis-
       tent Perl processes.  See the mimedefang-multiplexor man page for additional information.

OPTIONS

       If  you invoke mimedefang with the single argument prcap, it prints information about the version of Milter it is linked against and exits.
       Otherwise, you should invoke mimedefang as shown in the second line of the SYNOPSIS.

       -U user
	      Runs mimedefang as user rather than root.  The user argument must match the argument to mimedefang-multiplexor's -U option as well.

       -z spooldir
	      Set the spool directory to spooldir.  If this option is omitted, the spool directory defaults to /var/spool/MIMEDefang.

       -p connection
	      The -p switch is required and specifies the milter connection type.  Typically, you should run mimedefang on the	same  computer	as
	      sendmail.  Therefore, you should use a UNIX-domain socket for the connection type.  The suggested value for the -p switch is mimede-
	      fang.sock under the spool directory.

       -m mx_socket_name
	      Specifies the socket for communicating with mimedefang-multiplexor(8).  The mx_socket_name specifies the	path  of  the  UNIX-domain
	      socket.  See mimedefang-multiplexor(8) for details.

       -b backlog
	      Sets  the  "backlog" argument to the listen(2) system call to backlog.  If this option is omitted, then the operating-system default
	      backlog is used.

       -d     The -d switch causes mimedefang not to delete the temporary spool files it creates for incoming messages.   This	is  for  debugging
	      purposes only and should never be used on a production mail server.

       -r     Causes  mimedefang to perform a relay check before processing any messages.  It calls into a user-supplied Perl function called fil-
	      ter_relay with the IP address and host name of the sending relay.  (See mimedefang-filter(5) for details.)

       -H     Causes mimedefang to perform a HELO check before processing any messages.  It calls into a user-supplied Perl function  called  fil-
	      ter_helo with the IP address and host name of the sending relay, and the HELO argument.  (See mimedefang-filter(5) for details.)

       -s     Causes  mimedefang to perform a sender check before processing the message body.	It calls into a user-supplied Perl function called
	      filter_sender with the envelope address of the sender.  (See mimedefang-filter(5) for details.)

       -t     Causes mimedefang to perform recipient checks before processing the message body.  It  calls  into  a  user-supplied  Perl  function
	      called filter_recipient with the envelope address of each recipient.  (See mimedefang-filter(5) for details.)

       -q     Permits  the  multiplexor to queue new connections.  See the section QUEUEING REQUESTS in the mimedefang-multiplexor man page.  Note
	      that this option and the -R option are mutually-exclusive.  If you supply -q, then -R is ignored.

       -k     Causes mimedefang not to delete working directories if a filter fails.  This lets you obtain the message which caused the filter	to
	      fail and determine what went wrong.  mimedefang logs the directory containing the failed message using syslog.

       -P fileName
	      Causes mimedefang to write its process-ID (after becoming a daemon) to the specified file.

       -R num Normally,  mimedefang  tempfails	a  new	SMTP connection if there are no free slaves.  Supplying the -R num option makes mimedefang
	      tempfail new connections if there are fewer than num free slaves, unless the connection is from the local host.  This allows you	to
	      favour connections from localhost so your clientmqueue doesn't build up.	Note that supplying -R 0 is subtly different from omitting
	      the option; in this case, mimedefang permits new connections from localhost to queue, but not connections from other  hosts  (unless
	      you also supply the -q option.)

	      The  purpose  of	the  -R option is to reserve resources for clientmqueue runs.  Otherwise, on a very busy mail server, clientmqueue
	      runs can starve for a long time, leading to delays for locally-generated or streamed mail.  We recommend using a	small  number  for
	      num; probably no more than 3 or 10% of the total number of slaves (whichever is smaller.)

	      Note that this option and the -q option are mutually-exclusive.  If you supply -q, then -R is ignored.

       -C     Conserve	file  descriptors by opening and closing disk files more often.  (Disk files are never held open across Milter callbacks.)
	      While this shortens the length of time a file descriptor is open, it also leaves more opportunities for the open to fail.  We do not
	      recommend the use of this flag except on very busy systems that exhibit failures due to a shortage of file descriptors.

       -T     Causes mimedefang to log the run-time of the Perl filter using syslog.

       -x string
	      Add  string  as  the content of the X-Scanned-By: header.  If you set string to the empty string (i.e. -x ""), then no X-Scanned-By:
	      header will be added.

       -X     Do not add an X-Scanned-By: header.  Specifying -X is equivalent to specifying -x "".

       -D     Do not fork into the background and become a daemon.  Instead, stay in the foreground.  Useful mainly for debugging or if you have a
	      supervisory process managing mimedefang.

       -M     This option is obsolete; it is accepted for backward-compatibility, but is ignored.

       -N     Normally,  mimedefang sees all envelope recipients, even ones that Sendmail knows to be invalid.	If you don't want Sendmail to per-
	      form a milter callback for recipients it knows to be invalid, invoke mimedefang with the -N flag.  Please note that this	flag  only
	      works with Sendmail and Milter 8.14.0 and newer.	It has no effect if you're running an older version of Sendmail or Milter.

       -S facility
	      Specifies  the  syslog facility for log messages.  The default is mail.  See openlog(3) for a list of valid facilities.  You can use
	      either the short name ("mail") or long name ("LOG_MAIL") for the facility name.

       -a macro
	      Pass the value of the specified Sendmail macro through to the Perl filter.  You can repeat the -a option to write more  macros  than
	      the  built-in  defaults.	Note that in addition to asking mimedefang to pass the macro value to the filter, you must configure Send-
	      mail to pass the macro through to mimedefang using the confMILTER_MACROS_ENVFROM definition in Sendmail's m4 configuration file.

       -c     Strip "bare" carriage-returns (CR) characters from the message body.  A bare CR should never appear in  an  e-mail  message.   Older
	      versions	of  mimedefang used to strip them out automatically, but now they are left in by default.  The -c option enables the older
	      behavior.

       -h     Print usage information and exit.

OPERATION

       When mimedefang starts, it connects to sendmail using the milter API.  (See the Sendmail 8.11 documentation.)  For each	incoming  message,
       mimedefang  creates  a temporary directory and saves information in the directory.  At various phases during the SMTP conversation, mimede-
       fang communicates with mimedefang-multiplexor to perform various operations.  mimedefang-multiplexor manages a pool of persistent Perl pro-
       cesses that actually perform the mail scanning operations.

       When  a	Perl  process scans an e-mail, the temporary spool directory contains certain files; details of the communication protocol between
       mimedefang and the Perl script are in mimedefang-protocol(7).

WARNINGS

       mimedefang does violence to the flow of e-mail.	The Perl filter is quite picky and assumes that  MIME  e-mail  messages  are  well-formed.
       While  I have tried to make the script safe, I take no responsibility for lost or mangled e-mail messages or any security holes this script
       may introduce.

AUTHOR

       mimedefang was written by David F. Skoll <dfs@roaringpenguin.com>.  The mimedefang home page is http://www.mimedefang.org/.

SEE ALSO

       mimedefang.pl(8), mimedefang-filter(5), mimedefang-multiplexor(8), mimedefang-protocol(7)

4th Berkeley Distribution					  8 February 2005						     MIMEDEFANG(8)