LOCATION
/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.
- 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.
(Note: Feature is experimental.)
- 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.
(Note: Feature is experimental.)
- 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.
(Note: Feature is experimental.)
- 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 [email protected] (with all superdomains checked in sequence, so "foo.example.com" would first check "[email protected]", then "[email protected]", then "[email protected]"), 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.
(Note: Feature is experimental.)
- 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.
(Note: Feature is experimental.)
- 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.
(Note: Feature is experimental.)
- VBR-PurgeFields (string)
-
If set, arranges to remove X-VBR-Certifiers and X-VBR-Type fields on messages
prior to sending them.
(Note: Feature is experimental.)
- VBR-TrustedCertifiers (string)
-
A colon or comma sparated list of trusted certifiers to accept when
verifying VBR-Info header field.
(Note: Feature is experimental.)
- 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.
(Note: Feature is experimental.)
- VBR-Type (string)
-
This default VBR type if not specified in the X-VBR-Type header field.
(Note: Feature is experimental.)
- 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 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
- /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.