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rexecd(8)
NAME
  rexecd - The remote execution server

SYNOPSIS
  rexecd [-s]

OPTIONS
  -s  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:

   1.  The server reads characters from the socket 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 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.

   3.  A null-terminated username of at most 16 bytes is retrieved on the
       initial socket.

   4.  A null-terminated, unencrypted password of at most 80 bytes 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 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.

   7.  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 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 bytes.

  Password too long.
      The password is longer than 80 bytes.

  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 password was supplied.

  No remote directory.
      The chdir command to the home directory failed.

  Try again.
      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 stderr and is not preceded by a
      option byte.

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

FILES
  /usr/sbin/rexecd
      Specifies the command path

SEE ALSO
  Functions: rexec(3)

  Files: securettys(4)

Index for Section 8

Alphabetical listing for R

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