rexecd(8)

NAME

rexecd - remote execution server

SYNOPSIS

rexecd

DESCRIPTION

Rexecd is the server for the rexec(3) routine. The server

provides
remote execution facilities with authentication based on us

er names and
passwords.

Rexecd listens for service requests at the port indicated in

the ``exec''
service specification; see services(5). When a service re

quest is
received the following protocol is initiated:

1. The server reads characters from the socket up to a NUL

(` ') byte.
The resultant string is interpreted as an ASCII number,

base 10.

2. If the number received in step 1 is non-zero, it is in

terpreted as
the port number of a secondary stream to be used for

the stderr. A
second connection is then created to the specified port

on the
client's machine.

3. A NUL terminated user name of at most 16 characters is

retrieved on
the initial socket.

4. A NUL terminated, unencrypted password of at most 16

characters is
retrieved on the initial socket.

5. A NUL terminated command to be passed to a shell is re

trieved on the
initial socket. The length of the command is limited

by the upper
bound on the size of the system's argument list.

6. Rexecd then validates the user as is done at login time

and, if the
authentication was successful, changes to the user's

home directory,
and establishes the user and group protections of the

user. If any
of these steps fail the connection is aborted with a

diagnostic mes
sage returned.

7. A NUL byte is returned on the initial socket and the

command line is
passed to the normal login shell of the user. The

shell inherits
the network connections established by rexecd.

DIAGNOSTICS

Except for the last one listed below, all diagnostic mes

sages are
returned on the initial socket, after which any network con

nections are
closed. An error is indicated by a leading byte with a val

ue of 1 (0 is
returned in step 7 above upon successful completion of all

the steps
prior to the command execution).

username too long
The name is longer than 16 characters.

password too long
The password is longer than 16 characters.

command too longThe command line passed exceeds the size of the ar

gument list (as
configured into the system).

Login incorrect.
No password file entry for the user name existed or

the wrong
password was supplied.

No remote directory.
The chdir command to the home directory failed.

Try again.
A fork by the server failed.

<shellname>: ...
The user's login shell could not be started. This

message is
returned on the connection associated with the

stderr, and is not
preceded by a flag byte.

SEE ALSO

rexec(3)

BUGS

A facility to allow all data and password exchanges to be

encrypted
should be present.

HISTORY

The rexecd command appeared in 4.2BSD.

Linux NetKit (0.17) March 16, 1991 Linux

NetKit (0.17)