Provided by: spf-tools-perl_3.20240206-1_all 
NAME
spfd - (Mail::SPF) - Simple forking daemon to provide SPF query services
VERSION
2.000
SYNOPSIS
spfd --port|-p port [--set-user|-u uid|username] [--set-group|-g gid|groupname] [OPTIONS]
spfd --socket|-s filename [--socket-user uid|username] [--socket-group gid|groupname] [--socket-perms
octal-perms] [--set-user|-u uid|username] [--set-group|-g gid|groupname] [OPTIONS]
spfd --version|-V
spfd --help
DESCRIPTION
spfd is a simple forking Sender Policy Framework (SPF) query server. spfd receives and answers SPF
requests on a TCP/IP or UNIX domain socket. For more information on SPF see
<https://tools.ietf.org/html/rfc7208>.
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 --version form prints version information of spfd. The --help form prints usage information for
spfd.
OPTIONS
spfd takes any of the following OPTIONS:
--default-explanation string
--def-exp string
Use the specified string as the default explanation if the authority domain does not specify an
explanation string of its own.
--hostname hostname
Use hostname as the host name of the local system instead of auto-detecting it.
--debug
Print out debug information about spfd's operation, incoming requests, and the responses sent.
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 option=value, where the following options are
supported:
versions
A comma-separated list of SPF version numbers of SPF records that may be used. 1 means that "v=spf1"
records should be used. 2 means that "spf2.0" records should be used. Defaults to 1,2, i.e., uses
any SPF records that are available. Records of a higher version are preferred.
scope
The authorization scope of the identity that should be checked. Defaults to 'mfrom'. The following
scope values are supported: 'helo', 'mfrom', 'pra'. See "new" in Mail::SPF::Request for more
information.
identity
Required. The sender identity whose authorization should be checked. This is a domain name for the
"helo" scope, and an e-mail address for the "mfrom" and "pra" scopes.
ip_address
Required for checks with the "helo", "mfrom", and "pra" scopes. The IP address of the host claiming
the identity that is being checked. Can be either an IPv4 or an IPv6 address. An IPv4-mapped IPv6
address (e.g. '::ffff:192.168.0.1') is treated as an IPv4 address.
helo_identity
The "HELO" SMTP transaction parameter in the case that the main identity is of a scope other than
"helo". This identity is then used merely for the expansion of "%{h}" macros during the policy
evaluation of the main identity. If unspecified with a scope other than "helo", defaults to
"unknown". If the main identity is of the "helo" scope, this option is unused.
RESPONSE
spfd responds to SPF requests with similar series of lines of the form key=value. The most important
response keys are:
result
The result code of the SPF check:
pass The specified IP address is an authorized SMTP sender for the identity.
fail The specified IP address is not an authorized SMTP sender for the identity.
softfail The specified IP address is not an authorized SMTP sender for the identity, however the
authority domain is still testing out its SPF policy.
neutral The identity's authority domain makes no assertion about the status of the IP address.
permerror A permanent error occurred while evaluating the authority domain's policy (e.g., a syntax
error in the SPF record). Manual intervention is required from the authority domain.
temperror A temporary error occurred while evaluating the authority domain's policy (e.g., a DNS
error). Try again later.
none There is no applicable SPF policy for the identity domain.
local_explanation
A locally generated explanation of the SPF result.
authority_explanation
The authority domain's explanation for the SPF result. Be aware that the authority domain may be a
malicious party and thus the authority explanation should not be trusted blindly. See RFC 4408,
10.5, for a detailed discussion of this issue.
received_spf_header
An appropriate "Received-SPF" header field for the SPF result.
spf_record
The authority domain's SPF record that was used for the policy evaluation.
EXAMPLE
A running spfd could be tested using the "netcat" utility like this (line breaks added for clarity):
$ echo -e "identity=user@example.com\nip_address=1.2.3.4\n" \
| nc localhost 5970
result=fail
local_explanation=example.com: Sender is not authorized by default to use
'user@example.com' in 'mfrom' identity (mechanism '-all' matched)
authority_explanation=Rejected by SPF record
received_spf_header=Received-SPF: fail (example.com: Sender is not
authorized by default to use 'user@example.com' in 'mfrom' identity
(mechanism '-all' matched)) receiver=localhost; identity=mfrom;
envelope-from="user@example.com"; client-ip=1.2.3.4
spf_record=v=spf1 mx -all
COMPATIBILITY
spfd has undergone the following interface changes compared to earlier versions:
2.000
• A new preferred request style has been introduced. Instead of the old "sender" request option,
which is specific to the "MAIL FROM" SMTP identity, a generic "identity" option should now be
specified. In addition, a "scope" option may be given to specify the identity's scope, otherwise
a scope of "mfrom" is assumed. The old "ip" and "helo" options have been replaced by the
"ip_address" and "helo_identity" options, respectively.
This is how legacy requests with the "mfrom" scope would translate to the new preferred request
style:
Legacy request style | New request style
----------------------------+---------------------------------------
| scope=mfrom
sender=<mfrom-identity> | identity=<mfrom-identity>
ip=<ip-address> | ip_address=<ip-address>
helo=<helo-identity> | helo_identity=<helo-identity>
A new response style featuring new response values has also been introduced:
Legacy response style | New response style
----------------------------+---------------------------------------
result=<result-code> | result=<result-code>
header_comment=<local-exp> | local_explanation=<local-exp>
smtp_comment=<local-exp | authority_explanation=<authority-exp>
or authority-exp> |
spf_record=<spf-record> | spf_record=<spf-record>
| received_spf_header=<header>
The legacy request style is deprecated but still supported for backwards compatibility. The
legacy response values are still returned for backwards compatibility in addition to the new
response values, but may be removed in the future. Adjust your code to use the new request and
response styles.
• The former "unknown" and "error" result codes have been renamed to "permerror" and "temperror",
respectively, in order to comply with RFC 4408 terminology.
• SPF checks with an empty identity are no longer supported. In the case of an empty "MAIL FROM"
SMTP transaction parameter, perform a check with the "helo" scope directly.
SEE ALSO
Mail::SPF, spfquery(1)
<http://tools.ietf.org/html/rfc4408>
AUTHORS
This version of spfd is a complete rewrite by Julian Mehnle <julian@mehnle.net>, based on an earlier
version written by Meng Weng Wong <mengwong+spf@pobox.com>.
perl v5.38.2 2024-02-09 SPFD(8p)