mandos-clients.conf(5) Configuration file for the Mandos server




The file /etc/mandos/clients.conf is a configuration file for mandos(8), read by it at startup. The file needs to list all clients that should be able to use the service. The settings in this file can be overridden by runtime changes to the server, which it saves across restarts. (See the section called "PERSISTENT STATE" in mandos(8).) However, any changes to this file (including adding and removing clients) will, at startup, override changes done during runtime.

The format starts with a [section header] which is either [DEFAULT] or [client name]. The client name can be anything, and is not tied to a host name. Following the section header is any number of "option=value" entries, with continuations in the style of RFC 822. "option: value" is also accepted. Note that leading whitespace is removed from values. Values can contain format strings which refer to other values in the same section, or values in the "DEFAULT" section (see the section called "EXPANSION"). Lines beginning with "#" or ";" are ignored and may be used to provide comments.


Note: all option values are subject to start time expansion, see the section called "EXPANSION".

Unknown options are ignored. The used options are as follows:

approval_delay = TIME

This option is optional.

How long to wait for external approval before resorting to use the approved_by_default value. The default is "PT0S", i.e. not to wait.

The format of TIME is the same as for timeout below.

approval_duration = TIME

This option is optional.

How long an external approval lasts. The default is 1 second.

The format of TIME is the same as for timeout below.

approved_by_default = { 1 | yes | true | on | 0 | no | false | off }

Whether to approve a client by default after the approval_delay. The default is "True".

checker = COMMAND

This option is optional.

This option overrides the default shell command that the server will use to check if the client is still up. Any output of the command will be ignored, only the exit code is checked: If the exit code of the command is zero, the client is considered up. The command will be run using "/bin/sh -c", so PATH will be searched. The default value for the checker command is "fping -q -- %%(host)s". Note that mandos-keygen, when generating output to be inserted into this file, normally looks for an SSH server on the Mandos client, and, if it find one, outputs a checker option to check for the client's key fingerprint - this is more secure against spoofing.

In addition to normal start time expansion, this option will also be subject to runtime expansion; see the section called "EXPANSION".

extended_timeout = TIME

This option is optional.

Extended timeout is an added timeout that is given once after a password has been sent successfully to a client. The timeout is by default longer than the normal timeout, and is used for handling the extra long downtime while a machine is booting up. Time to take into consideration when changing this value is file system checks and quota checks. The default value is 15 minutes.

The format of TIME is the same as for timeout below.

fingerprint = HEXSTRING

This option is required.

This option sets the OpenPGP fingerprint that identifies the public key that clients authenticate themselves with through TLS. The string needs to be in hexadecimal form, but spaces or upper/lower case are not significant.

host = STRING

This option is optional, but highly recommended unless the checker option is modified to a non-standard value without "%%(host)s" in it.

Host name for this client. This is not used by the server directly, but can be, and is by default, used by the checker. See the checker option.

interval = TIME

This option is optional.

How often to run the checker to confirm that a client is still up. Note: a new checker will not be started if an old one is still running. The server will wait for a checker to complete until the below "timeout" occurs, at which time the client will be disabled, and any running checker killed. The default interval is 2 minutes.

The format of TIME is the same as for timeout below.

secfile = FILENAME

This option is only used if secret is not specified, in which case this option is required.

Similar to the secret, except the secret data is in an external file. The contents of the file should not be base64-encoded, but will be sent to clients verbatim.

File names of the form ~user/foo/bar and $ENVVAR/foo/bar are supported.


If this option is not specified, the secfile option is required to be present.

If present, this option must be set to a string of base64-encoded binary data. It will be decoded and sent to the client matching the above fingerprint. This should, of course, be OpenPGP encrypted data, decryptable only by the client. The program mandos-keygen(8) can, using its --password option, be used to generate this, if desired.

Note: this value of this option will probably be very long. A useful feature to avoid having unreadably-long lines is that a line beginning with white space adds to the value of the previous line, RFC 822-style.

timeout = TIME

This option is optional.

The timeout is how long the server will wait, after a successful checker run, until a client is disabled and not allowed to get the data this server holds. By default Mandos will use 5 minutes. See also the extended_timeout option.

The TIME is specified as an RFC 3339 duration; for example "P1Y2M3DT4H5M6S" meaning one year, two months, three days, four hours, five minutes, and six seconds. Some values can be omitted, see RFC 3339 Appendix A for details.

enabled = { 1 | yes | true | on | 0 | no | false | off }

Whether this client should be enabled by default. The default is "true".


There are two forms of expansion: Start time expansion and runtime expansion.


Any string in an option value of the form "%(foo)s" will be replaced by the value of the option foo either in the same section, or, if it does not exist there, the [DEFAULT] section. This is done at start time, when the configuration file is read.

Note that this means that, in order to include an actual percent character ("%") in an option value, two percent characters in a row ("%%") must be entered.


This is currently only done for the checker option.

Any string in an option value of the form "%%(foo)s" will be replaced by the value of the attribute foo of the internal "Client" object in the Mandos server. The currently allowed values for foo are: "approval_delay", "approval_duration", "created", "enabled", "expires", "fingerprint", "host", "interval", "last_approval_request", "last_checked_ok", "last_enabled", "name", "timeout", and, if using D-Bus, "dbus_object_path". See the source code for details. Currently, none of these attributes except "host" are guaranteed to be valid in future versions. Therefore, please let the authors know of any attributes that are useful so they may be preserved to any new versions of this software.

Note that this means that, in order to include an actual percent character ("%") in a checker option, four percent characters in a row ("%%%%") must be entered. Also, a bad format here will lead to an immediate but silent run-time fatal exit; debug mode is needed to expose an error of this kind.


The file described here is /etc/mandos/clients.conf


The format for specifying times for timeout and interval is not very good.

The difference between %%(foo)s and %(foo)s is obscure.

Please report bugs to the Mandos development mailing list: <[email protected]> (subscription required). Note that this list is public. The developers can be reached privately at <[email protected]> (OpenPGP key fingerprint 153A 37F1 0BBA 0435 987F 2C4A 7223 2973 CA34 C2C4 for encrypted mail).


timeout = PT5M
interval = PT2M
checker = fping -q -- %%(host)s
# Client "foo"
fingerprint =  7788 2722 5BA7 DE53 9C5A  7CFA 59CF F7CD BD9A 5920
secret =
host =
interval = PT1M
# Client "bar"
fingerprint = 3e393aeaefb84c7e89e2f547b3a107558fca3a27
secfile = /etc/mandos/bar-secret
timeout = PT15M
approved_by_default = False
approval_delay = PT30S


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