Manual page for REXECD(8C)
rexecd, in.rexecd - remote execution server
This program is available with the
software installation option. Refer to
[a manual with the abbreviation INSTALL]
for information on how to install optional software.
is the server for the
routine. The server provides remote execution facilities
with authentication based on user names and encrypted passwords.
It is invoked automatically as needed by
and then executes the following protocol:
- The server reads characters from the socket up
to a null
byte. The resultant string is interpreted as an
number, base 10.
- 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
A second connection is then created to the specified
port on the client's machine.
- A null terminated user name of at most 16 characters
is retrieved on the initial socket.
- A null terminated, encrypted, password of at most
16 characters is retrieved on the initial socket.
- 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.
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.
- A null byte is returned on the connection associated
and the command line is passed to the normal login
shell of the user. The
shell inherits the network connections established by
All diagnostic messages are returned on the connection
associated with the
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.
command to the home directory failed.
- Try again.
by the server failed.
- /usr/bin/sh: ...
The user's login shell could not be started.
as opposed to
is a security breach which allows people to probe a system for users
with null passwords.
A facility to allow all data exchanges
to be encrypted should be present.
Created by unroff & hp-tools.
© by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97