rexecd — remote execution server

       A facility to allow all data and password exchanges to be encrypted should be present.

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 NUL (‘\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 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 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  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.

       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).

       usernametoolong
               The name is longer than 16 characters.

       passwordtoolong
               The password is longer than 16 characters.

       commandtoolong
               The command line passed exceeds the size of the argument list (as configured into the system).

       Loginincorrect.
               No password file entry for the user name existed or the wrong password was supplied.

       Noremotedirectory.
               The chdir command to the home directory failed.

       Tryagain.
               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.

       The rexecd command appeared in 4.2BSD.

Linux NetKit (0.17)                              March 16, 1991                                        REXECD(8)

       rexecd — remote execution server

rexec(3)

rexecd