opendkim.conf(5) FreeBSD File Formats Manual opendkim.conf(5)
NAME
opendkim.conf - Configuration file for opendkim
LOCATION
/usr/local/etc/opendkim.conf
DESCRIPTION
opendkim(8) implements the DKIM specification for signing and verifying
e-mail messages on a per-domain basis. This file is its configuration
file.
Blank lines are ignored. Lines containing a hash ("#") character are
truncated at the hash character to allow for comments in the file.
Other content should be the name of a parameter, followed by white
space, followed by the value of that parameter, each on a separate
line.
For parameters that are Boolean in nature, only the first byte of the
value is processed. For positive values, the following are accepted:
"T", "t", "Y", "y", "1". For negative values, the following are
accepted: "F", "f", "N", "n", "0".
Many, but not all, of these parameters are also available as command
line options to opendkim(8). However, new parameters are generally not
added as command line options so the complete set of options is
available here, and thus use of the configuration file is encouraged.
In some future release, the set of available command line options is
likely to get trimmed.
See the opendkim(8) man page for details about how and when the
configuration file contents are reloaded.
Some of these parameters are listed as having a type of "dataset". See
the opendkim(8) man page for a description of such parameters.
Unless otherwise stated, Boolean values default to "false", integer
values default to 0, and string and dataset values default to being
undefined.
PARAMETERS
AllowSHA1Only (Boolean)
Permit verify mode when only SHA1 support is available. RFC6376
requires that verifiers implement both SHA1 and SHA256 support.
Setting this feature changes the absence of SHA256 support from
an error to a warning.
AlwaysAddARHeader (Boolean)
Add an "Authentication-Results:" header field even to unsigned
messages from domains with no "signs all" policy. The reported
DKIM result will be "none" in such cases. Normally unsigned
mail from non-strict domains does not cause the results header
field to be added.
AuthservID (string)
Sets the "authserv-id" to use when generating the
Authentication-Results: header field after verifying a message.
The default is to use the name of the MTA processing the
message. If the string "HOSTNAME" is provided, the name of the
host running the filter (as returned by the gethostname(3)
function) will be used.
AuthservIDWithJobID (Boolean)
If "true", requests that the authserv-id portion of the added
Authentication-Results: header fields contain the job ID of the
message being evaluated.
AutoRestart (Boolean)
Automatically re-start on failures. Use with caution; if the
filter fails instantly after it starts, this can cause a tight
fork(2) loop.
AutoRestartCount (integer)
Sets the maximum automatic restart count. After this number of
automatic restarts, the filter will give up and terminate. A
value of 0 implies no limit; this is the default.
AutoRestartRate (string)
Sets the maximum automatic restart rate. If the filter begins
restarting faster than the rate defined here, it will give up
and terminate. This is a string of the form n/t[u] where n is
an integer limiting the count of restarts in the given interval
and t[u] defines the time interval through which the rate is
calculated; t is an integer and u defines the units thus
represented ("s" or "S" for seconds, the default; "m" or "M" for
minutes; "h" or "H" for hours; "d" or "D" for days). For
example, a value of "10/1h" limits the restarts to 10 in one
hour. There is no default, meaning restart rate is not limited.
Background (Boolean)
Causes opendkim to fork and exits immediately, leaving the
service running in the background. The default is "true".
BaseDirectory (string)
If set, instructs the filter to change to the specified
directory using chdir(2) before doing anything else. This means
any files referenced elsewhere in the configuration file can be
specified relative to this directory. It's also useful for
arranging that any crash dumps will be saved to a specific
location.
BodyLengthDB (dataset)
Requests that opendkim include a "l=" body length tag when the
set contains any of the envelope recipient addresses. The
addresses presented are tested against the database in various
forms as described under the SigningTable setting (below). This
feature of the protocol exists to improve the likelihood that a
signature will survive transit through a mailing list server, as
they commonly append footers to messages. Note, however, that
this creates a potential security issue since someone could add
arbitrary text to the signed message and the signature would
still validate. See the DKIM specification for details.
BogusKey (string)
Instructs the filter to treat a passing signature associated
with a bogus (forged) key in a special way. Possible values are
neutral (return a "neutral" result), none (take no special
action) and fail (return a "fail" result; this is the default).
CaptureUnknownErrors (Boolean)
When set, and on systems where MTA quarantine is available, the
filter will request quarantine of a message that results in an
internal error or resource exhaustion.
Canonicalization (string)
Selects the canonicalization method(s) to be used when signing
messages. When verifying, the message's DKIM-Signature: header
field specifies the canonicalization method. The recognized
values are relaxed and simple as defined by the DKIM
specification. The default is simple. The value may include
two different canonicalizations separated by a slash ("/")
character, in which case the first will be applied to the header
and the second to the body.
ChangeRootDirectory (string)
Requests that the operating system change the effective root
directory of the process to the one specified here prior to
beginning execution. chroot(2) requires superuser access. A
warning will be generated if UserID is not also set.
ClockDrift (integer)
Sets the tolerance in seconds to be applied when determining
whether a signature was either expired or generated in the
future. The default is 300.
Diagnostics (Boolean)
Requests the inclusion of "z=" tags in signatures, which encode
the original header field set for use by verifiers when
diagnosing verification failures. Not recommended for normal
operation.
DiagnosticDirectory (string)
Directory into which to write diagnostic reports when message
verification fails on a message bearing a "z=" tag. If not set
(the default), these files are not generated.
DisableCryptoInit (Boolean)
If set, skips initialization of the SSL library initialization
steps, which are normaly required in multi-threaded
environments. This assumes some other library opendkim is using
will do the required initialization and shutdown.
DNSConnect (Boolean)
Requests that the asynchronous resolver start using TCP
immediately rather than using UDP until TCP is actually needed.
Does not work with all resolvers.
DNSTimeout (integer)
Sets the DNS timeout in seconds. A value of 0 causes an
infinite wait. The default is 5. Ignored if not using an
asynchronous resolver package. See also the NOTES section
below.
Domain (dataset)
A set of domains whose mail should be signed by this filter.
Mail from other domains will be verified rather than being
signed.
This parameter is not required if a SigningTable is in use; in
that case, the list of signed domains is implied by the lines in
that file.
This parameter is ignored if a KeyTable is defined.
DomainKeysCompat (boolean)
If set, backward compatibility with DomainKeys (RFC4870) key
records is enabled. When not set, such keys are considered to
be syntactically invalid. The default is "false".
DontSignMailTo (dataset)
A set of e-mail address, mail to which should never be signed by
the filter. Note that this is an "any" feature; if any one of
the recipients of the message matches a member of this list, the
message will not be signed.
EnableCoredumps (boolean)
On systems that have such support, make an explicit request to
the kernel to dump cores when the filter crashes for some
reason. Some modern UNIX systems suppress core dumps during
crashes for security reasons if the user ID has changed during
the lifetime of the process. Currently only supported on Linux.
ExemptDomains (dataset)
Specifies a set of domains, mail from which should be ignored
entirely by the filter. This is similar to the PeerList setting
except that it bases its decision on the sender of the message
as identified from the header fields or other message data, not
the identity of the SMTP client sending the message.
ExternalIgnoreList (dataset)
Identifies a set of "external" hosts that may send mail through
the server as one of the signing domains without credentials as
such. This has the effect of suppressing the "external host
(hostname) tried to send mail as (domain)" log messages.
Entries in the data set should be of the same form as those of
the PeerList option below. The set is empty by default.
FinalPolicyScript (string)
Gives the name of a Lua script that should be run after the
entire message has been received. This can be used to enact
local policy decisions such as message rejection, quarantine,
rerouting, etc. based on signatures found on the message, the
results of attempts to verify them, and other properties of the
message or signatures. See opendkim-lua(3) for details.
FixCRLF (Boolean)
Requests that the DKIM library convert bare CRs and LFs to CRLFs
during body canonicalization, anticipating that an MTA somewhere
before delivery will do that conversion anyway. The default is
to leave them as-is.
IdentityHeader (string)
This specifies the header field where an identity is stored.
(Experimental feature not enabled for this installation.)
IdentityHeaderRemove (Boolean)
Remove the IdentityHeader after signing. (Experimental feature
not enabled for this installation.)
IgnoreMalformedMail (boolean)
Silently passes malformed messages without alteration. This
includes messages that fail the RequiredHeaders check, if
enabled. The default is to pass those messages but add an
Authentication-Results field indicating that they were
malformed.
Include (string)
Names a file to be opened and read as an additional
configuration file. Nesting is allowed to a maximum of five
levels.
InternalHosts (dataset)
Identifies a set internal hosts whose mail should be signed
rather than verified. Entries in this data set follow the same
form as those of the PeerList option below. If not specified,
the default of "127.0.0.1" is applied. Naturally, providing a
value here overrides the default, so if mail from 127.0.0.1
should be signed, the list provided here should include that
address explicitly.
KeepAuthResults (boolean)
Suppresses removal of Authentication-Results header fields
containing DKIM results apparently added by this filter (usually
the result of a misconfiguration or a forgery).
KeepTemporaryFiles (boolean)
Instructs the filter to create temporary files containing the
header and body canonicalizations of messages that are signed or
verified. The location of these files can be set using the
TemporaryDirectory parameter. Intended only for debugging
verification problems.
KeyFile (string)
Gives the location of a PEM-formatted private key to be used for
signing all messages. Ignored if a KeyTable is defined.
KeyTable (dataset)
Gives the location of a file mapping key names to signing keys.
If present, overrides any KeyFile setting in the configuration
file. The data set named here maps each key name to three
values: (a) the name of the domain to use in the signature's
"d=" value; (b) the name of the selector to use in the
signature's "s=" value; and (c) either a private key or a path
to a file containing a private key. If the first value consists
solely of a percent sign ("%") character, it will be replaced by
the apparent domain of the sender when generating a signature.
If the third value starts with a slash ("/") character, or "./"
or "../", then it is presumed to refer to a file from which the
private key should be read, otherwise it is itself a PEM-encoded
private key or a base64-encoded DER private key; a "%" in the
third value in this case will be replaced by the apparent domain
name of the sender. The SigningTable (see below) is used to
select records from this table to be used to add signatures
based on the message sender.
LDAPAuthMechanism (string)
Names the authentication mechanism to use when connecting to an
LDAP server. The default is the empty string, meaning "simple"
authentication should be done.
LDAPAuthName (string)
Specifies the authenticating name to use when using SASL to
authenticate to an LDAP server. Requires SASL support be
installed on the local system. There is no default.
LDAPAuthRealm (string)
Specifies the authentication realm to use when using SASL to
authenticate to an LDAP server. Requires SASL support be
installed on the local system. There is no default.
LDAPAuthUser (string)
Specifies the authenticating user to use when using SASL to
authenticate to an LDAP server. Requires SASL support be
installed on the local system. There is no default.
LDAPBindPassword (string)
Specifies the password to use when conducting an LDAP "bind"
operation. There is no default.
LDAPBindUser (string)
Specifies the user ID to use when conducting an LDAP "bind"
operation. There is no default.
LDAPDisableCache (Boolean)
Suppresses creation of a local cache in front of LDAP queries.
LDAPKeepaliveIdle (integer)
Sets the number of seconds a connection to an LDAP server needs
to remain idle before TCP starts sending keepalive probes. If
not specified, the LDAP library default is used.
LDAPKeepaliveInterval (integer)
Sets the interval in seconds between TCP keepalive probes. If
not specified, the LDAP library default is used.
LDAPKeepaliveProbes (integer)
Sets the maximum number of keepalive probes TCP should send
before abandoning the connection. If not specified, the LDAP
library default is used.
LDAPTimeout (integer)
Sets the time in seconds after which an LDAP operation should be
abandoned. The default is 5.
LDAPUseTLS (Boolean)
Indicates whether or not a TLS connection should be established
when contacting an LDAP server. The default is "False".
LogResults (boolean)
If logging is enabled (see Syslog below), requests that the
results of evaluation of all signatures that were at least
partly intact (i.e., the "d=", "s=", and "b=" tags could be
extracted).
LogWhy (boolean)
If logging is enabled (see Syslog below), issues very detailed
logging about the logic behind the filter's decision to either
sign a message or verify it. The logic behind the decision is
non-trivial and can be confusing to administrators not familiar
with its operation. A description of how the decision is made
can be found in the OPERATIONS section of the opendkim(8) man
page. This causes a large increase in the amount of log data
generated for each message, so it should be limited to debugging
use and not enabled for general operation.
MacroList (dataset)
Defines a set of MTA-provided macros that should be checked to
see if the sender has been determined to be a local user and
therefore whether or not the message should be signed. If a
value is specified matching a macro name in the data set, the
value of the macro must match a value specified (matching is
case-sensitive), otherwise the macro must be defined but may
contain any value. The set is empty by default, meaning macros
are not considered when making the sign-verify decision. The
general format of the value is value1[|value2[|...]]; if one or
more value is defined then the macro must be set to one of the
listed values, otherwise the macro must be set but can contain
any value.
In order for the macro and its value to be available to the
filter for checking, the MTA must send it during the protocol
exchange. This is either accomplished via manual configuration
of the MTA to send the desired macros or, for MTA/filter
combinations that support the feature, the filter can request
those macros that are of interest. The latter is a feature
negotiated at the time the filter receives a connection from the
MTA and its availability depends upon the version of milter used
to compile the filter and the version of the MTA making the
connection.
This data set must be of type "file" or "csl".
MaximumHeaders (integer)
Defines the maximum number of bytes the header block of a
message may consume before the filter will reject the message.
This mitigates a denial-of-service attack in which a client
connects to the MTA and begins feeding an unbounded number of
header fields of arbitrary size; since the filter keeps a cache
of these, the attacker could cause the filter to allocate an
unspecified amount of memory. The default is 65536; a value of
0 removes the limit.
MaximumSignaturesToVerify (integer)
Defines the maximum number of signatures on a message for which
verification should be conducted. The default is three.
Signatures are selected from the top of the message downward.
If TrustSignaturesFrom is set, signatures from domains in that
data set are always verified, which may consume part or all of,
or even exceed, this limit.
MaximumSignedBytes (integer)
Specifies the maximum number of bytes of message body to be
signed. Messages shorter than this limit will be signed in
their entirety. Setting this value implies use of BodyLengthDB
for all addresses.
MilterDebug (integer)
Sets the debug level to be requested from the milter library.
The default is 0.
Minimum (string)
Instructs the verification code to fail messages for which a
partial signature was received. There are three possible
formats: min indicating at least min bytes of the message must
be signed (or if the message is smaller than min then all of it
must be signed); min% requiring that at least min percent of the
received message must be signed; and min+ meaning there may be
no more than min bytes of unsigned data appended to the message
for it to be considered valid.
MinimumKeyBits (integer)
Establishes a minimum key size for acceptable signatures.
Signatures with smaller key sizes, even if they otherwise pass
DKIM validation, will me marked as invalid. The default is
1024, which accepts all signatures. A value of 0 causes the
default to be used.
Mode (string)
Selects operating modes. The string is a concatenation of
characters that indicate which mode(s) of operation are desired.
Valid modes are s (signer) and v (verifier). The default is sv
except in test mode (see the opendkim(8) man page) in which case
the default is v. When signing mode is enabled, one of the
following combinations must also be set: (a) Domain, KeyFile,
Selector, no KeyTable, no SigningTable; (b) KeyTable,
SigningTable, no Domain, no KeyFile, no Selector; (c) KeyTable,
SetupPolicyScript, no Domain, no KeyFile, no Selector.
MTA (dataset)
A set of MTA names (a la the sendmail(8) DaemonPortOptions Name
parameter) whose mail should be signed by this filter. There is
no default, meaning MTA name is not considered when making the
sign-verify decision.
MTACommand (string)
Specifies the path to an executable to be used for sending mail
such as that generated by SendReports. The default is
/usr/sbin/sendmail. The executable should accept typical
sendmail(8) command line options "-t" (take addresses from
message body) and "-f" (set envelope sender), accept the new
message on its standard input, and return a non-zero exit status
on any error.
MultipleSignatures (Boolean)
Allow addition of multiple signatures when a signing table is in
use. See SigningTable for more information.
MustBeSigned (dataset)
Specifies a set of header fields that, if present, must be
covered by the DKIM signature when verifying a message. If a
header field in this set is present in the message and is not
signed, the filter will treat even an otherwise valid signature
as invalid. The default is an empty list.
Nameservers (string)
Provides a comma-separated list of IP addresses that are to be
used when doing DNS queries to retrieve DKIM keys, VBR records,
etc. These override any local defaults built in to the resolver
in use, which may be defined in /etc/resolv.conf or hard-coded
into the software.
NoHeaderB (Boolean)
If set, this feature suppresses the use of "header.b" tags in
added Authentication-Results header fields. The default is
"false", which means those tags will be applied.
OmitHeaders (dataset)
Specifies a set of header fields that should be omitted when
generating signatures. If an entry in the list names any header
field that is mandated by the DKIM specification, the entry is
ignored. A set of header fields is listed in the DKIM
specification (RFC6376, Section 5.4) as "SHOULD NOT" be signed;
the default list for this parameter contains those fields
(Return-Path, Received, Comments, Keywords, Bcc, Resent-Bcc and
DKIM-Signature). To omit no headers, simply use the string "."
(or any string that will match no header field names).
Specifying a list with this parameter replaces the default
entirely, unless one entry is "*" in which case the list is
interpreted as a delta to the default; for example, "*,+foobar"
will use the entire default list plus the name "foobar", while
"*,-Bcc" would use the entire default list except for the "Bcc"
entry.
On-BadSignature (string)
Selects the action to be taken when a signature fails to
validate. Possible values (with abbreviated forms in
parentheses): accept (a) accept the message; discard (d) discard
the message; quarantine (q) quarantine the message; reject (r)
reject the message; tempfail (t) temp-fail the message. The
default is accept. Note that the "t" (testing) flag in a DKIM
key bypasses this behaviour; a bad signature that references a
testing flag will still be delivered, though the added
Authentication-Results field will indicate both the failed
result and the test mode so that consumers of the message can
take appropriate action.
On-Default (string)
Selects the action to be taken when any verification or internal
error of any kind is encountered. This is processed before the
other "On-" values so it can be used as a blanket setting
followed by specific overrides.
On-DNSError (string)
Selects the action to be taken when a transient DNS error is
encountered. Possible values are the same as those for
On-BadSignature. The default is tempfail.
On-InternalError (string)
Selects the action to be taken when an internal error of some
kind is encountered. Possible values are the same as those for
On-BadSignature. The default is tempfail.
On-KeyNotFound (string)
Selects the action to be taken when the key referenced by a
signature is not present in the DNS. Possible values are the
same as those for On-BadSignature. The default is accept.
On-NoSignature (string)
Selects the action to be taken when a message arrives unsigned.
Possible values are the same as those for On-BadSignature. The
default is accept.
On-Security (string)
Selects the action to be taken when a message arrives containing
properties that may be a security concern. Possible values are
the same as those for On-BadSignature. The default is tempfail.
On-SignatureError (string)
Selects the action to be taken when a message cannot be signed
because of issues with the message or the key provided for
signing. Possible values are the same as those for
On-BadSignature. The default is reject.
OversignHeaders (dataset)
Specifies a set of header fields that should be included in all
signature header lists (the "h=" tag) once more than the number
of times they were actually present in the signed message. The
set is empty by default. The purpose of this, and especially of
listing an absent header field, is to prevent the addition of
important fields between the signer and the verifier. Since the
verifier would include that header field when performing
verification if it had been added by an intermediary, the signed
message and the verified message were different and the
verification would fail. Note that listing a field name here
and not listing it in the SignHeaders list is likely to generate
invalid signatures.
PeerList (dataset)
Identifies a set of "peers" that identifies clients whose
connections should be accepted without processing by this
filter. The set should contain on each line a hostname, domain
name (e.g. ".example.com"), IP address, an IPv6 address
(including an IPv4 mapped address), or a CIDR-style IP
specification (e.g. "192.168.1.0/24"). An entry beginning with
a bang ("!") character means "not", allowing exclusions of
specific hosts that are otherwise members of larger sets. Host
and domain names are matched first, then the IP or IPv6 address
depending on the connection type. More precise entries are
preferred over less precise ones, i.e. "192.168.1.1" will match
before "!192.168.1.0/24". The text form of IPv6 addresses will
be forced to lowercase when queried (RFC5952), so the contents
of this data set should also use lowercase. The IP address
portion of an entry may optionally contain square brackets; both
forms (with and without) will be checked.
PidFile (string)
Specifies the path to a file that should be created at process
start containing the process ID.
POPDBFile (dataset)
Requests that the filter consult a set for IP addresses that
should be allowed for signing. This feature was designed for
POP-before-SMTP datastores. (Not enabled for this
installation.)
Quarantine (Boolean)
Requests that messages which fail verification be quarantined by
the MTA. (Requires a sufficiently recent version of the milter
library.)
QueryCache (Boolean)
Instructs the DKIM library to maintain its own local cache of
keys and policies retrieved from DNS, rather than relying on the
nameserver for caching service. Useful if the nameserver being
used by the filter is not local. (Not enabled for this
installation.)
RedirectFailuresTo (address)
Messages bearing signatures that failed to verify are redirected
to the specified address. The original envelope recipient set
is recorded in the header before redirection occurs. By
default, no redirection is done.
RemoveARAll (Boolean)
Removes all Authentication-Results: header fields that also
satisfy the requirements of RemoveARFrom below. By default,
only those containing a DKIM result are removed.
RemoveARFrom (dataset)
Defines a set of hostnames whose Authentication-Results: header
fields should be removed before the message is passed for
delivery. By default only those header fields matching the
local host's canonical name will be removed. Matching is only
done on full hostnames (e.g. "host.example.com") or on domain
names (e.g. ".example.com").
RemoveOldSignatures (Boolean)
Removes all existing signatures when operating in signing mode.
ReplaceHeaders (data set)
Defines a set of header fields that should be affected by the
text replacement rules defined by the ReplaceRules setting. By
default, all header fields are included. (Experimental feature
not enabled for this installation.)
ReplaceRules (string)
Specifies a file containing a list of text replacement rules
that are applied to the message header fields to replace certain
content expected to be changed as the message passes through
local MTAs. This can be used to accommodate expected changes
such as are made to From: fields by MTA "masquerade" features.
Each entry in the file consists of a POSIX regular expression,
followed by a tab (ASCII 9), followed by the text that should be
used to replace the text matching the expression. The '#'
character denotes the beginning of a comment and text from that
point on in a single line is ignored. Blank lines are also
skipped. (Experimental feature not enabled for this
installation.)
ReportAddress (string)
Specifies the string to use in the From: header field for
outgoing reports (see SendReports below). If not specified, the
executing user and local hostname will be used to construct the
address.
ReportBccAddress (string)
Specifies address(es) to include in a Bcc: header field on
outgoing reports (see SendReports below). If multiple addresses
are required, they should be comma separated.
RequestReports (boolean)
When signing, includes a request for signature evaluation
failures in the signature. (See RFC6651 for details.)
RequiredHeaders (boolean)
Checks all messages for compliance with RFC5322 header field
count requirements. Non-compliant messages are rejected.
RequireSafeKeys (boolean)
When reading a key file, a message will be logged if the key
file has the read or write bit set other than for the owner or
for a group that the executing process is in. With this feature
set to "true", the filter will further consider this an error
and refuse to make use of the file's contents. The default is
"true".
ResignAll (boolean)
Where ResignMailTo triggers a re-signing action, this flag
indicates whether or not all mail should be signed (if set)
versus only verified mail being signed (if not set). The
default is "false". (Experimental feature not enabled for this
installation.)
ResignMailTo (dataset)
Checks each message recipient against the specified dataset for
a matching record. The full address is checked in each case,
then the hostname, then each domain preceded by ".". If there
is a match, the value returned is presumed to be the name of a
key in the KeyTable (if defined) to be used to re-sign the
message in addition to verifying it. If there is a match
without a KeyTable, the default key is applied. (Experimental
feature not enabled for this installation.)
ResolverConfiguration (string)
Provides the given string as configuration information to the
underlying resolver. For the standard UNIX resolver, this is
unused; for Unbound, the string contains a filename that is
considered to be a configuration file. There is no default.
ResolverTracing (Boolean)
Requests resolver tracing features be enabled, if available.
The effect of this depends on how debugging features of the
resolver might be implemented. Currently only effective with
the OpenDKIM asynchronous resolver library.
ScreenPolicyScript (string)
Gives the name of a Lua script that should be run after all of
the header fields have been processed for a message; in
particular, this is useful after all DKIM signatures have been
detected and initial evaluation has been done. The script has
access to all of the header fields and connection information
and can that certain signatures be ignored based on that
information. See opendkim-lua(3) for details.
SelectCanonicalizationHeader (string)
Defines a header field name which, if present, adjusts which
canonicalization will be used to generate an outgoing signature.
Overrides the Canonicalization setting if the header field is
present. The default is "X-Canonicalization".
Selector (string)
Defines the name of the selector to be used when signing
messages. See the DKIM specification for details. Used only
when signing with a single key; see the SigningTable parameter
below for more information.
This parameter is ignored if a KeyTable is defined.
SenderHeaders (dataset)
Specifies an ordered list of header fields that should be
searched to determine the sender of a message. The first header
field found is the one whose value is used. This is mainly used
when signing for deciding which signing request(s) to make. By
default, the "From" header field is the only one checked. See
the OmitHeaders setting for a description of possible values.
SenderMacro (string)
Use the milter macro string to determine the sender of the
message. (Experimental feature not enabled for this
installation.)
SendReports (Boolean)
If true, when a signature verification fails and the signature
included a reporting request ("r=y") and the signing domain
advertises a reporting address (i.e. ra=user) in a reporting
record in the DNS, the filter will send a structured report to
that address containing details needed to reproduce the problem.
See RFC6651 for a complete description of this mechanism.
SetupPolicyScript (string)
Gives the name of a Lua script that should be run once all
header fields for a message have arrived. The script has access
to all of the header fields and connection information and can
request DKIM verification or signing based on that information.
See opendkim-lua(3) for details.
SignatureAlgorithm (string)
Selects the signing algorithm to use when generating signatures.
Use 'opendkim -V' to see the list of supported algorithms. The
default is rsa-sha256 if it is available, otherwise it will be
rsa-sha1.
SignatureTTL (integer)
Sets the time-to-live, in seconds, of signatures generated by
the filter. If not set, no expiration time is added to
signatures.
SignHeaders (dataset)
Specifies the set of header fields that should be included when
generating signatures. If the list omits any header field that
is mandated by the DKIM specification, those fields are
implicitly added. By default, those fields listed in the DKIM
specification as "SHOULD" be signed (RFC6376, Section 5.4) will
be signed by the filter. See the OmitHeaders configuration
option for more information about the format and interpretation
of this field.
SigningTable (dataset)
Defines a table used to select one or more signatures to apply
to a message based on the address found in the From: header
field. Keys in this table vary depending on the type of table
used; values in this data set should include one field that
contains a name found in the KeyTable (see above) that
identifies which key should be used in generating the signature,
and an optional second field naming the signer of the message
that will be included in the "i=" tag in the generated
signature. Note that the "i=" value will not be included in the
signature if it conflicts with the signing domain (the "d="
value).
If the first field contains only a "%" character, it will be
replaced by the domain found in the From: header field.
Similarly, within the optional second field, any "%" character
will be replaced by the domain found in the From: header field.
If this table specifies a regular expression file ("refile"),
then the keys are wildcard patterns that are matched against the
address found in the From: header field. Entries are checked in
the order in which they appear in the file.
For all other database types, the full user@host is checked
first, then simply host, then user@.domain (with all
superdomains checked in sequence, so "foo.example.com" would
first check "user@foo.example.com", then "user@.example.com",
then "user@.com"), then .domain, then user@*, and finally *.
In any case, only the first match is applied, unless
MultipleSignatures is enabled in which case all matches are
applied.
SMTPURI (string)
Specifies a URI (e.g., "smtp://localhost") to which mail should
be sent via SMTP when notifications are generated. (Not enabled
for this installation.)
Socket (string)
Specifies the socket that should be established by the filter to
receive connections from sendmail(8) in order to provide
service. socketspec is in one of two forms: local:path, which
creates a UNIX domain socket at the specified path, or
inet:port[@host] or inet6:port[@host] which creates a TCP socket
on the specified port and in the specified protocol family. If
the host is not given as either a hostname or an IP address, the
socket will be listening on all interfaces. A literal IP
address must be enclosed in square brackets. This option is
mandatory either in the configuration file or on the command
line.
SoftStart (Boolean)
If set, the inability to connect and authenticate to an LDAP or
SQL server will not prevent the filter from starting, and
reconnections will be attempted for each query. The default is
"False".
SoftwareHeader (Boolean)
Causes opendkim to add an "DKIM-Filter" header field indicating
the presence of this filter in the path of the message from
injection to delivery. The product's name, version, and the job
ID are included in the header field's contents. Note that the
header field is not added if the Mode setting causes the message
to be ignored (e.g., if only signing mode is enabled and the
configuration causes the message not to be signed, or only
verify mode is enabled and configuration would otherwise have
caused the message to be signed, then it will not have this
header field added).
Statistics (filename)
This specifies a file in which to store DKIM transaction
statistics. See opendkim-stats(8) for a mechanism to parse the
file's contents, and opendkim-importstats() for a mechanism to
translate the file's contents into SQL database insertions.
(Experimental feature not enabled for this installation.)
StatisticsName (string)
Defines the name to be used as the reporting host in statistics
logs. By default, the local host's name returned by
gethostname(3) is used. (Experimental feature not enabled for
this installation.)
StatisticsPrefix (string)
When AnonymousStatistics is enabled, this string may be
specified and will be prepended to all data before hashing for
more complete anonymization. This means two records from
different sources referencing the same source will still produce
different hashes, meaning such correlation is now only possible
within the data from a single repoter.
StrictHeaders (Boolean)
If set, instructs the DKIM library to refuse processing of a
message if the header field count does not conform to RFC5322
Section 3.6.
StrictTestMode (Boolean)
Selects strict CRLF mode during testing (see the -t command line
flag in the opendkim(8) man page); messages for which all header
fields and body lines are not CRLF-terminated are considered
malformed and will produce an error.
SubDomains (Boolean)
Sign subdomains of those listed by the Domain parameter as well
as the actual domains.
Syslog (Boolean)
Log via calls to syslog(3) any interesting activity.
SyslogFacility (string)
Log via calls to syslog(3) using the named facility. The
facility names are the same as the ones allowed in
syslog.conf(5). The default is "mail".
SyslogSuccess (Boolean)
Log via calls to syslog(3) additional entries indicating
successful signing or verification of messages.
TemporaryDirectory (string)
Specifies the directory in which temporary canonicalization
files should be written. The default is to use the libdkim
default location, currently /tmp.
TestDNSData (data set)
Provides a data set whose keys will be treated as DNS record
names and values as TXT record contents. Intended for use
during automated testing.
TestPublicKeys (string)
Names a file from which public keys should be read. Intended
for use only during automated testing.
TrustAnchorFile (string)
Specifies a file from which trust anchor data should be read
when doing DNS queries and applying the DNSSEC protocol. This
is currently ignored unless the underlying library is compiled
to use Unbound; see the documentation at at http://unbound.net
for the expected format of this file.
TrustSignaturesFrom (dataset)
This value consists of a set of domains that are considered
trustworthy in terms of third-party signatures. That is, if a
message arrives with a signature from a domain that doesn't
match the domain in the From: header, this setting determines
whether or not that signature will be trusted. If this value is
undefined, all signatures are trusted.
UMask (integer)
Requests a specific permissions mask to be used for file
creation. This only really applies to creation of the socket
when Socket specifies a UNIX domain socket, and to the PidFile
(if any); temporary files are created by the mkstemp(3) function
that enforces a specific file mode on creation regardless of the
process umask. See umask(2) for more information.
UnprotectedKey (string)
Instructs the filter to treat a passing signature associated
with a key found in an insecure (i.e. not protected by DNSSEC)
DNS record in a special way. Possible values are neutral
(return a "neutral" result), none (take no special action; this
is the default) and fail (return a "fail" result).
UserID (string)
Attempts to become the specified userid before starting
operations. The value is of the form userid[:group]. The
process will be assigned all of the groups and primary group ID
of the named userid unless an alternate group is specified.
VBR-Certifiers (string)
The default certifiers if not specified in X-VBR-Certifiers
header field. (Experimental feature not enabled for this
installation.)
VBR-PurgeFields (string)
If set, arranges to remove X-VBR-Certifiers and X-VBR-Type
fields on messages prior to sending them. (Experimental feature
not enabled for this installation.)
VBR-TrustedCertifiers (string)
A colon or comma sparated list of trusted certifiers to accept
when verifying VBR-Info header field. (Experimental feature not
enabled for this installation.)
VBR-TrustedCertifiersOnly (Boolean)
By default, the certifiers that are in both the trusted
certifiers list (above) and those in the message's VBR-Info
header field will be checked for vouching. With this option
set, the trusted certifiers will be checked and the ones claimed
by the message will be ignored. (Experimental feature not
enabled for this installation.)
VBR-Type (string)
This default VBR type if not specified in the X-VBR-Type header
field. (Experimental feature not enabled for this
installation.)
WeakSyntaxChecks (Boolean)
Requests that the library continue processing messages even if
syntax errors are discovered early in message analysis. This
means, for example, that a signed message with a mangled From:
field will still proceed to verification even if the author's
domain could not be determined.
NOTES
When using DNS timeouts (see the DNSTimeout option above), be sure not
to use a timeout that is larger than the timeout being used for
interaction between sendmail and the filter. Otherwise, the MTA could
abort a message while waiting for a reply from the filter, which in
turn is still waiting for a DNS reply.
Features that involve specification of IPv4 addresses or CIDR blocks
will use the _addr§ion=3">inet_addr(3) function to parse that information. Users
should be familiar with the way that function handles the non-trivial
cases (for example, "192.0.2/24" and "192.0.2.0/24" are not the same
thing).
FILES
/usr/local/etc/opendkim.conf
Default location of this file.
VERSION
This man page covers version 2.10.3 of opendkim.
COPYRIGHT
Copyright (c) 2007, 2008, Sendmail, Inc. and its suppliers. All rights
reserved.
Copyright (c) 2009-2015, The Trusted Domain Project. All rights
reserved.
SEE ALSO
opendkim(8), opendkim-lua(3), sendmail(8)
RFC5451 - Message Header Field for Indicating Message Authentication
Status
RFC5617 - DKIM Author Domain Signing Practises
RFC5965 - An Extensible Format for Email Feedback Reports
RFC6008 - Authentication-Results Registration for Differentiating among
Cryptographic Results
RFC6376 - DomainKeys Identified Mail
RFC6651 - Extensions to DomainKeys Identified Mail (DKIM) for Failure
Reporting
The Trusted Domain Project opendkim.conf(5)
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