REMCTL

Section: remctl (1)
Updated: 2018-05-05
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NAME

remctl - Remote execution tool

SYNOPSIS

remctl [-dhv] [-b source-ip] [-p port] [-s service]
host command [subcommand [parameters ...]]

DESCRIPTION

remctl is a program that allows a user to execute commands remotely on a server that is running the remctld daemon. remctl does not interpret the commands given to it. It passes them to the server and displays the return message. The commands must be defined on the server-side before a remctl client can execute them, and the user running remctl must be authorized to execute the particular command on the server.

Access to remote commands is authenticated via Kerberos GSS-API, so a user must have a ticket granting ticket to use remctl. All transmissions to and from the remctld server are encrypted using GSS-API's security layer.

host is the hostname of the target server. command and subcommand together specify the command to run and correspond to the command names in the configuration file on the server. parameters are any additional command-line parameters to pass to the remote command.

OPTIONS

The start of each option description is annotated with the version of remctl in which that option was added with its current meaning.

-b source-ip: [3.0] When connecting to the remote remctl server, use source-ip as the source IP address. This can be useful on multihomed systems where the remctl connections need to be made over a particular network. source-ip must be an IP address, not a hostname, and can be either an IPv4 or IPv6 address (assuming IPv6 is supported).
-d: [1.10] Turn on extra debugging output of the client-server interaction.
-h: [1.10] Show a brief usage message and then exit.
-p port: [1.0] Connect to the server on port. If this option isn't given, the client first tries the registered remctl port (4373) and then falls back on the legacy port (4444) if that fails.
-s service: [1.0] Authenticate to the server with a service ticket for service rather than the default server identity of host/hostname. This may be necessary with, for instance, a server where remctld is not running as root.
-v: [1.10] Print the version of remctl and exit.

EXIT STATUS

remctl will exit with the exit status returned by the remote command. If some network or authentication error occurred and remctl was unable to run the remote command or retrieve its exit status, or if remctl was called with invalid arguments, remctl will exit with status 1.

EXAMPLES

Release an AFS volume called ls.tripwire:

    remctl lsdb afs release ls.tripwire

COMPATIBILITY

The default port was changed to the IANA-registered port of 4373 in version 2.11.

Support for IPv6 was added in version 2.4.

CAVEATS

If no principal is specified with -s, remctl canonicalizes the server host name using DNS before connecting. This ensures that the network connection and the GSS-API authentication use the same server name even if some common DNS-based load-balancing schemes are in use. To disable this canonicalization, specify the server principal using -s.

The default behavior, when the port is not specified, of trying 4373 and falling back to 4444 will be removed in a future version of remctl in favor of using the "remctl" service in /etc/services if set and then falling back on only 4373. 4444 was the poorly-chosen original remctl port and should be phased out.

When using Heimdal with triple-DES keys and talking to old servers that only speak version one of the remctl protocol, remctl may have problems with MIC verification. This doesn't affect new clients and servers since the version two protocol doesn't use MICs. If you are using Heimdal and run into MIC verification problems, see the COMPATIBILITY section of gssapi(3).

NOTES

The remctl port number, 4373, was derived by tracing the diagonals of a QWERTY keyboard up from the letters "remc" to the number row.

AUTHOR

remctl was originally written by Anton Ushakov. Updates and current maintenance are done by Russ Allbery <eagle@eyrie.org>.

COPYRIGHT AND LICENSE

Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved. This file is offered as-is, without any warranty.

SPDX-License-Identifier: FSFAP