NAME
rexecd - remote execution server

SYNOPSIS
/etc/rexecd

DESCRIPTION
Rexecd is the server for the rexec(3) routine. The server provides
remote execution facilities with authentication based on user names
and passwords.

Rexecd listens for service requests at the port indicated in the
"exec" service specification; see services(5). When a service
request is received the following protocol is initiated:

1) The server reads characters from the socket up to a null
(‘ ’) 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
interpreted 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 null terminated user name of at most 16 characters is
retrieved on the initial socket.

4) A null terminated, unencrypted password of at most 16
characters is retrieved on the initial socket.

5) A null terminated command to be passed to a shell is retrieved
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 message returned.

7) A null 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 messages are
returned on the initial socket, after which any network connections
are closed. An error is indicated by a leading byte with a value
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 long "
The command line passed exceeds the size of the argument list (as
configured into the system).

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

"Password incorrect."
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.