RSH(1)

💖 NAME 💖

rsh — remote shell (yes bestie, the RSH(1) page from the General Commands Manual, we're doing this)

🦋 SYNOPSIS 🦋

rsh host [-l username] [-n] [-d] [-k realm] [-f | -F] [-x] [-PN | -PO]
command

✨ DESCRIPTION ✨

Okay so rsh connects to the specified host, then runs the specified command. It copies its standard input to the remote command, sends the remote command's standard output back to its own standard output, and sends the remote command's standard error back to its own standard error. This implementation of rsh will accept any port for the standard error stream. Interrupt, quit and terminate signals are propagated to the remote command, and rsh normally terminates when the remote command does.

Each user may have a private authorization list in a file .k5login in their login directory. Every line in that file should contain a Kerberos principal name of the form principal/instance@realm. If there is a ~/.k5login file, then access is granted to the account if and only if the originating user is authenticated to one of the principals named in the ~/.k5login file. Otherwise, the originating user will be granted access to the account if and only if the authenticated principal name of the user can be mapped to the local account name using the aname -> lname mapping rules (see krb5_anadd(8) for more details).

🎀 OPTIONS 🎀

• -l username — sets the remote username to username. Otherwise, the remote username will be the same as the local username.
• -x — causes the network session traffic to be encrypted. This applies only to the input and output streams, not the command line.
• -f — cause nonforwardable Kerberos credentials to be forwarded to the remote machine for use by the specified command. They will be removed when command finishes. This option is mutually exclusive with the -F option.
• -F — cause forwardable Kerberos credentials to be forwarded to the remote machine for use by the specified command. They will be removed when command finishes. This option is mutually exclusive with the -f option.
• -k realm — causes rsh to obtain tickets for the remote host in realm instead of the remote host's realm as determined by krb_realmofhost(3).
• -d — turns on socket debugging (via setsockopt(2)) on the TCP sockets used for communication with the remote host.
• -n — redirects input from the special device /dev/null (see the BUGS section below).
• -PN — explicitly request the new version of the Kerberos rcmd protocol.
• -PO — explicitly request the old version of the Kerberos rcmd protocol.

The new protocol avoids many security problems found in the old one, but is not interoperable with older servers. (An "input/output error" and a closed connection is the most likely result of attempting this combination.) If neither option is specified, some simple heuristics are used to guess which to try.

If you omit command, then instead of executing a single command, you will be logged in on the remote host using rlogin(1).

Shell metacharacters which are not quoted are interpreted on the local machine, while quoted metacharacters are interpreted on the remote machine. Thus the command

rsh otherhost cat remotefile >> localfile

appends the remote file remotefile to the local file localfile, while

rsh otherhost cat remotefile ">>" otherremotefile

appends remotefile to otherremotefile.

🌸 FILES 🌸

• /etc/hosts
• ~/.k5login (on remote host) — file containing Kerberos principals that are allowed access.

👑 SEE ALSO 👑

rlogin(1), kerberos(3), krb_sendauth(3), krb_realmofhost(3), kshd(8)

💀 BUGS 💀

If you are using csh(1) and put a rsh(1) in the background without redirecting its input away from the terminal, it will block even if no reads are posted by the remote command. If no input is desired you should redirect the input of rsh to /dev/null using the -n option.

You cannot run an interactive command (like rogue(6) or vi(1)); use rlogin(1).

Stop signals stop the local rsh process only; this is arguably wrong, but currently hard to fix for reasons too complicated to explain here.

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✨ Sign-off: that's the whole RSH(1) page from the General Commands Manual — the original footer is just RSH(1) with no extra source/version/date info, so that's your lot, bestie 💖