rexecd(8)						      System Manager's Manual							 rexecd(8)

NAME

       rexecd - The remote execution server

SYNOPSIS

       rexecd [-s]

OPTIONS

       Causes  rexecd  to  check for the ptys keyword in the /etc/securettys file and to deny execution of the request if it is from root and on a
       pseudoterminal.

DESCRIPTION

       The rexecd daemon is the server for the rexec(3) routine.  The server provides remote execution facilities  with  authentication  based	on
       usernames and passwords.

       The  rexecd  daemon  listens for service requests at the port indicated in the exec service specification; see services(4).  When a service
       request is received, the following protocol is initiated: The server reads characters from the socket up to a null (`') byte.	The resul-
       tant  string is interpreted as an ASCII number, base 10.  If the number received in step 1 is nonzero, 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.	 A
       null-terminated	username  of  at  most 16 bytes is retrieved on the initial socket.  A null-terminated, unencrypted password of at most 80
       bytes 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.  The rexecd server then validates the user
       as is done at login time and, if started with the -s option, verifies that the /etc/securettys file is not setup to deny the user.  If  the
       authentication  was  successful,  rexecd changes to the user's home directory, and establishes the user and group protections for the user.
       If any of these steps fail, the connection is aborted with a diagnostic message returned.  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 diagnostic message listed, all diagnostic messages are returned on the initial socket, after which any network connec-
       tions 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).	The name is longer than 16 bytes.  The password is longer than 80 bytes.  The command line
       passed exceeds the size of the argument list (as configured into the system).  No password file entry for the username existed.	The  wrong
       password  was supplied.	The chdir command to the home directory failed.  A fork by the server failed.  The user's login shell could not be
       started.  This message is returned on the connection associated with stderr and is not preceded by a flag byte.

CAUTIONS

       IndicatingLogin incorrect as opposed to Password incorrect is a security breach that allows people to probe a system for  users	with  null
       passwords.

FILES

       Specifies the command path

RELATED INFORMATION

       Functions: rexec(3)

       Files: securettys(4) delim off

																	 rexecd(8)