ultrix man page for rexecd

rexecd(8c)																rexecd(8c)

Name
       rexecd - remote execution server

Syntax
       /etc/rexecd

Description
       The  command  is  the  server  for the routine.	The server provides remote execution facilities with authentication based on usernames and
       encrypted passwords.

       The command is invoked by when it receives a connection on the port indicated in the ``exec'' service specification.  For further  informa-
       tion, see 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 username of at most 16 characters is retrieved on the initial socket.

       4) A null terminated 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) The  command	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

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 username existed.

       Password incorrect
       The wrong was password supplied.

       No remote directory
       The command to the home directory failed.

       Try again
       A fork by the server failed.

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

Restrictions
       Indicating ``Login incorrect'' as opposed to ``Password incorrect'' is a security breach which allows people to probe a	system	for  users
       with null passwords.

See Also
       inetd(8c)

																	rexecd(8c)