nrexecd(1M)                                              nrexecd(1M)


       NAME
             nrexecd - remote execution server

       SYNOPSIS
             nrexecd

       DESCRIPTION
             The nrexecd server provides remote execution facilities with
             authentication based on user names and encrypted passwords.
             It is invoked automatically as needed by nwnetd(1M), and then
             executes the following protocol:

             1)    The server reads characters from the stream up to a null
                   (\0) 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, encrypted 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)    nrexecd 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 connection associated
                   with the stderr and the command line is passed to the
                   normal login shell of the user.  The shell inherits the
                   network connections established by nrexecd.





                           Copyright 1994 Novell, Inc.               Page 1

      nrexecd(1M)                                              nrexecd(1M)


         Diagnostics
            All diagnostic messages are returned on the connection
            associated with the stderr, 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.

            /usr/bin/sh: ...
                  The user's login shell could not be started.

      REFERENCES
            nwnetd(1M)

      NOTICES
            Indicating Login incorrect as opposed to Password incorrect 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.





                          Copyright 1994 Novell, Inc.               Page 2