NAME

     rsh — remote shell

SYNOPSIS

     rsh [-45FGKdefnuxz] [-U string] [-p port] [-l username] [-P N|O] host [command]

DESCRIPTION

     rsh authenticates to the rshd(8) daemon on the remote host, and then executes the specified
     command.

     rsh copies its standard input to the remote command, and the standard output and error of
     the remote command to its own.

     Valid options are:

     -4, --krb4
             The -4 option requests Kerberos 4 authentication. Normally all supported
             authentication mechanisms will be tried, but in some cases more explicit control is
             desired.

     -5, --krb5
             The -5 option requests Kerberos 5 authentication. This is analogous to the -4
             option.

     -K, --broken
             The -K option turns off all Kerberos authentication. The security in this mode
             relies on reserved ports. The long name is an indication of how good this is.

     -n, --no-input
             The -n option directs the input from the /dev/null device (see the BUGS section of
             this manual page).

     -d      Enable setsockopt(2) socket debugging.

     -e, --no-stderr
             Don't use a separate socket for the stderr stream. This can be necessary if rsh-ing
             through a NAT bridge.

     -x, --encrypt
             The -x option enables encryption for all data exchange. This is only valid for
             Kerberos authenticated connections (see the BUGS section for limitations).

     -z      The opposite of -x.  This is the default, and is mainly useful if encryption has
             been enabled by default, for instance in the appdefaults section of /etc/krb5.conf
             when using Kerberos 5.

     -f, --forward
             Forward Kerberos 5 credentials to the remote host.  Also settable via appdefaults
             (see krb5.conf).

     -F, --forwardable
             Make the forwarded credentials re-forwardable.  Also settable via appdefaults (see
             krb5.conf).

     -l string, --user=string
             By default the remote username is the same as the local. The -l option or the
             username@host format allow the remote name to be specified.

     -n, --no-input
             Direct input from /dev/null (see the BUGS section).

     -p number-or-service, --port=number-or-service
             Connect to this port instead of the default (which is 514 when using old port based
             authentication, 544 for Kerberos 5 and non-encrypted Kerberos 4, and 545 for
             encrytpted Kerberos 4; subject of course to the contents of /etc/services).

     -P N|O|1|2, --protocol=N|O|1|2
             Specifies the protocol version to use with Kerberos 5.  N and 2 select protocol
             version 2, while O and 1 select version 1. Version 2 is believed to be more secure,
             and is the default. Unless asked for a specific version, rsh will try both.  This
             behaviour may change in the future.

     -u, --unique
             Make sure the remote credentials cache is unique, that is, don't reuse any existing
             cache. Mutually exclusive to -U.

     -U string, --tkfile=string
             Name of the remote credentials cache. Mutually exclusive to -u.

     -x, --encrypt
             The -x option enables encryption for all data exchange. This is only valid for
             Kerberos authenticated connections (see the BUGS section for limitations).

     -z      The opposite of -x.  This is the default, but encryption can be enabled when using
             Kerberos 5, by setting the libdefaults/encrypt option in krb5.conf(5).

EXAMPLES

     Care should be taken when issuing commands containing shell meta characters. Without
     quoting, these will be expanded on the local machine.

     The following command:

           rsh otherhost cat remotefile > localfile

     will write the contents of the remote remotefile to the local localfile, but:

           rsh otherhost 'cat remotefile > remotefile2'

     will write it to the remote remotefile2.

FILES

     /etc/hosts

SEE ALSO

     ktelnet(1), krb_realmofhost(3), krb_sendauth(3), hosts.equiv(5), krb5.conf(5), rhosts(5),
     kerberos(8) rshd(8)

HISTORY

     The rsh command appeared in 4.2BSD.

AUTHORS

     This implementation of rsh was written as part of the Heimdal Kerberos 5 implementation.

BUGS

     Some shells (notably csh(1)) will cause rsh to block if run in the background, unless the
     standard input is directed away from the terminal. This is what the -n option is for.

     The -x options enables encryption for the session, but for both Kerberos 4 and 5 the actual
     command is sent unencrypted, so you should not send any secret information in the command
     line (which is probably a bad idea anyway, since the command line can usually be read with
     tools like ps(1)).  Forthermore in Kerberos 4 the command is not even integrity protected,
     so anyone with the right tools can modify the command.