Annotation of 43BSDReno/libexec/rexecd/rexecd.8, revision 1.1

1.1     ! root        1: .\" Copyright (c) 1983 The Regents of the University of California.
        !             2: .\" All rights reserved.
        !             3: .\"
        !             4: .\" Redistribution and use in source and binary forms are permitted provided
        !             5: .\" that: (1) source distributions retain this entire copyright notice and
        !             6: .\" comment, and (2) distributions including binaries display the following
        !             7: .\" acknowledgement:  ``This product includes software developed by the
        !             8: .\" University of California, Berkeley and its contributors'' in the
        !             9: .\" documentation or other materials provided with the distribution and in
        !            10: .\" all advertising materials mentioning features or use of this software.
        !            11: .\" Neither the name of the University nor the names of its contributors may
        !            12: .\" be used to endorse or promote products derived from this software without
        !            13: .\" specific prior written permission.
        !            14: .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
        !            15: .\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
        !            16: .\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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        !            18: .\"    @(#)rexecd.8    6.4 (Berkeley) 6/24/90
        !            19: .\"
        !            20: .TH REXECD 8 "June 24, 1990"
        !            21: .UC 5
        !            22: .SH NAME
        !            23: rexecd \- remote execution server
        !            24: .SH SYNOPSIS
        !            25: .B rexecd
        !            26: .SH DESCRIPTION
        !            27: .I Rexecd
        !            28: is the server for the 
        !            29: .IR rexec (3)
        !            30: routine.  The server provides remote execution facilities
        !            31: with authentication based on user names and
        !            32: passwords.
        !            33: .PP
        !            34: .I Rexecd
        !            35: listens for service requests at the port indicated in
        !            36: the ``exec'' service specification; see
        !            37: .IR services (5).
        !            38: When a service request is received the following protocol
        !            39: is initiated:
        !            40: .IP 1)
        !            41: The server reads characters from the socket up
        !            42: to a null (`\e0') byte.  The resultant string is
        !            43: interpreted as an ASCII number, base 10.
        !            44: .IP 2)
        !            45: If the number received in step 1 is non-zero,
        !            46: it is interpreted as the port number of a secondary
        !            47: stream to be used for the 
        !            48: .BR stderr .
        !            49: A second connection is then created to the specified
        !            50: port on the client's machine.
        !            51: .IP 3)
        !            52: A null terminated user name of at most 16 characters
        !            53: is retrieved on the initial socket.
        !            54: .IP 4)
        !            55: A null terminated, unencrypted password of at most
        !            56: 16 characters is retrieved on the initial socket.  
        !            57: .IP 5)
        !            58: A null terminated command to be passed to a
        !            59: shell is retrieved on the initial socket.  The length of
        !            60: the command is limited by the upper bound on the size of
        !            61: the system's argument list.  
        !            62: .IP 6)
        !            63: .I Rexecd
        !            64: then validates the user as is done at login time
        !            65: and, if the authentication was successful, changes
        !            66: to the user's home directory, and establishes the user
        !            67: and group protections of the user.
        !            68: If any of these steps fail the connection is
        !            69: aborted with a diagnostic message returned.
        !            70: .IP 7)
        !            71: A null byte is returned on the initial socket
        !            72: and the command line is passed to the normal login
        !            73: shell of the user.  The
        !            74: shell inherits the network connections established
        !            75: by
        !            76: .IR rexecd .
        !            77: .SH DIAGNOSTICS
        !            78: Except for the last one listed below,
        !            79: all diagnostic messages are returned on the initial socket,
        !            80: after which any network connections are closed.
        !            81: An error is indicated by a leading byte with a value of
        !            82: 1 (0 is returned in step 7 above upon successful completion
        !            83: of all the steps prior to the command execution).
        !            84: .PP
        !            85: .B ``username too long''
        !            86: .br
        !            87: The name is
        !            88: longer than 16 characters.
        !            89: .PP
        !            90: .B ``password too long''
        !            91: .br
        !            92: The password is longer than 16 characters.
        !            93: .PP
        !            94: .B ``command too long ''
        !            95: .br
        !            96: The command line passed exceeds the size of the argument
        !            97: list (as configured into the system).
        !            98: .PP
        !            99: .B ``Login incorrect.''
        !           100: .br
        !           101: No password file entry for the user name existed.
        !           102: .PP
        !           103: .B ``Password incorrect.''
        !           104: .br
        !           105: The wrong was password supplied.
        !           106: .PP
        !           107: .B ``No remote directory.''
        !           108: .br
        !           109: The 
        !           110: .I chdir
        !           111: command to the home directory failed.
        !           112: .PP
        !           113: .B ``Try again.''
        !           114: .br
        !           115: A
        !           116: .I fork
        !           117: by the server failed.
        !           118: .PP
        !           119: .B ``<shellname>: ...''
        !           120: .br
        !           121: The user's login shell could not be started.
        !           122: This message is returned
        !           123: on the connection associated with the
        !           124: .BR stderr ,
        !           125: and is not preceded by a flag byte.
        !           126: .SH SEE ALSO
        !           127: rexec(3)
        !           128: .SH BUGS
        !           129: Indicating ``Login incorrect'' as opposed to ``Password incorrect''
        !           130: is a security breach which allows people to probe a system for users
        !           131: with null passwords.
        !           132: .PP
        !           133: A facility to allow all data and password exchanges to be encrypted should be
        !           134: present.

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