spfd(1) - Linux man page

Name

spfd - simple forking daemon to provide SPF query services

Version

2006-02-07

Synopsis

spfd --port port [--set-user uid│username] [--set-group gid│groupname]

spfd --socket filename [--socket-user uid│username] [--socket-group gid│groupname] [--socket-perms octal-perms] [--set-user uid│username] [--set-group gid│groupname]

spfd --help

Description

spfd is a simple forking Sender Policy Framework ( SPF ) query proxy server. spfd receives and answers SPF query requests on a TCP/IP or UNIX domain socket.

The --port form listens on a TCP/IP socket on the specified port. The default port is 5970.

The --socket form listens on a UNIX domain socket that is created with the specified filename. The socket can be assigned specific user and group ownership with the --socket-user and --socket-group options, and specific filesystem permissions with the --socket-perms option.

Generally, spfd can be instructed with the --set-user and --set-group options to drop root privileges and change to another user and group before it starts listening for requests.

The --help form prints usage information for spfd.

Request

A request consists of a series of lines delimited by \x0A ( LF ) characters (or whatever your system considers a newline). Each line must be of the form key=value, where the following keys are required:

ip The sender IP address.
sender: The envelope sender address (from the SMTP "MAIL FROM" command).
helo: The envelope sender hostname (from the SMTP "HELO" command).

Response

spfd responds to query requests with similar series of lines of the form key=value. The most important response keys are:

result

The result of the SPF query:

pass

The specified IP address is an authorized mailer for the sender domain/address.

fail

The specified IP address is not an authorized mailer for the sender domain/address.

softfail

The specified IP address is not an authorized mailer for the sender domain/address, however the domain is still in the process of transitioning to SPF .

neutral

The sender domain makes no assertion about the status of the IP address.

unknown

The sender domain has a syntax error in its SPF record.

error

A temporary DNS error occurred while resolving the sender policy. Try again later.

none

There is no SPF record for the sender domain.

smtp_comment

The text that should be included in the receiver's SMTP response.

header_comment

The text that should be included as a comment in the message's "Received-SPF:" header.

spf_record

The SPF record of the envelope sender domain.

For the description of other response keys see Mail::SPF::Query. For more information on SPF see <http://www.openspf.org>.

Example

A running spfd could be tested using the "netcat" utility like this:

$ echo -e "ip=11.22.33.44\nsender=user@pobox.com\nhelo=spammer.example.net\n" │ nc localhost 5970
result=neutral
smtp_comment=Please see http://spf.pobox.com/why.html?sender=user%40pobox.com&ip=11.22.33.44&receiver=localhost
header_comment=localhost: 11.22.33.44 is neither permitted nor denied by domain of user@pobox.com
guess=neutral
smtp_guess=
header_guess=
guess_tf=neutral
smtp_tf=
header_tf=
spf_record=v=spf1 ?all

Authors

This version of spfd was written by Meng Weng Wong <mengwong+spf@pobox.com>. Improved argument parsing was added by Julian Mehnle <julian@mehnle.net>.

This man-page was written by Julian Mehnle <julian@mehnle.net>.