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Annotation of 43BSDReno/lib/libc/net/rcmd.3, 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.
        !            17: .\"
        !            18: .\"    @(#)rcmd.3      6.10 (Berkeley) 6/23/90
        !            19: .\"
        !            20: .TH RCMD 3 "June 23, 1990"
        !            21: .UC 5
        !            22: .SH NAME
        !            23: rcmd, rresvport, ruserok \- routines for returning a stream to a remote command
        !            24: .SH SYNOPSIS
        !            25: .nf
        !            26: .PP
        !            27: .B "rem = rcmd(ahost, inport, locuser, remuser, cmd, fd2p);"
        !            28: .B char **ahost;
        !            29: .B int inport;
        !            30: .B "char *locuser, *remuser, *cmd;"
        !            31: .B int *fd2p;
        !            32: .PP
        !            33: .B s = rresvport(port);
        !            34: .B int *port;
        !            35: .PP
        !            36: .B "ruserok(rhost, superuser, ruser, luser);"
        !            37: .B char *rhost;
        !            38: .B int superuser;
        !            39: .B char *ruser, *luser;
        !            40: .fi
        !            41: .SH DESCRIPTION
        !            42: .I Rcmd
        !            43: is a routine used by the super-user to execute a command on
        !            44: a remote machine using an authentication scheme based
        !            45: on reserved port numbers.
        !            46: .I Rresvport
        !            47: is a routine which returns a descriptor to a socket
        !            48: with an address in the privileged port space.
        !            49: .I Ruserok
        !            50: is a routine used by servers
        !            51: to authenticate clients requesting service with
        !            52: .IR rcmd .
        !            53: All three functions are present in the same file and are used
        !            54: by the
        !            55: .IR rshd (8)
        !            56: server (among others).
        !            57: .PP
        !            58: .I Rcmd
        !            59: looks up the host
        !            60: .I *ahost
        !            61: using
        !            62: .IR gethostbyname (3),
        !            63: returning \-1 if the host does not exist.
        !            64: Otherwise
        !            65: .I *ahost
        !            66: is set to the standard name of the host
        !            67: and a connection is established to a server
        !            68: residing at the well-known Internet port
        !            69: .IR inport .
        !            70: .PP
        !            71: If the connection succeeds,
        !            72: a socket in the Internet domain of type SOCK_STREAM
        !            73: is returned to the caller, and given to the remote
        !            74: command as 
        !            75: .B stdin
        !            76: and
        !            77: .BR stdout .
        !            78: If
        !            79: .I fd2p
        !            80: is non-zero, then an auxiliary channel to a control
        !            81: process will be set up, and a descriptor for it will be placed
        !            82: in
        !            83: .IR *fd2p .
        !            84: The control process will return diagnostic
        !            85: output from the command (unit 2) on this channel, and will also
        !            86: accept bytes on this channel as being UNIX signal numbers, to be
        !            87: forwarded to the process group of the command.
        !            88: If
        !            89: .I fd2p
        !            90: is 0, then the 
        !            91: .B stderr
        !            92: (unit 2 of the remote
        !            93: command) will be made the same as the 
        !            94: .B stdout
        !            95: and no
        !            96: provision is made for sending arbitrary signals to the remote process,
        !            97: although you may be able to get its attention by using out-of-band data.
        !            98: .PP
        !            99: The protocol is described in detail in
        !           100: .IR rshd (8).
        !           101: .PP
        !           102: The
        !           103: .I rresvport
        !           104: routine is used to obtain a socket with a privileged
        !           105: address bound to it.  This socket is suitable for use
        !           106: by 
        !           107: .I rcmd
        !           108: and several other routines.  Privileged Internet ports are those
        !           109: in the range 0 to 1023.  Only the super-user
        !           110: is allowed to bind an address of this sort to a socket.
        !           111: .PP
        !           112: .I Ruserok
        !           113: takes a remote host's name, as returned by the
        !           114: .IR gethostbyaddr (3)
        !           115: routine, two user names and a flag indicating whether
        !           116: the local user's name is that of the super-user.  Then,
        !           117: if the user is
        !           118: .B NOT
        !           119: the super-user, it checks the files
        !           120: .IR /etc/hosts.equiv .
        !           121: If that lookup is not done, or is unsuccessful, the
        !           122: .I .rhosts
        !           123: in the local user's home directory is checked to see if the request for
        !           124: service is allowed.  If this file is owned by anyone other than the
        !           125: user or the super-user, or if it is writeable by anyone other than the
        !           126: owner, the check automatically fails.  A 0 is returned if the machine
        !           127: name is listed in the ``hosts.equiv'' file, or the host and remote
        !           128: user name are found in the ``.rhosts'' file; otherwise
        !           129: .I ruserok
        !           130: returns \-1.
        !           131: If the local domain (as obtained from \fIgethostname\fP\|(2))
        !           132: is the same as the remote domain, only the machine name need be specified.
        !           133: .SH SEE ALSO
        !           134: rlogin(1), rsh(1), intro(2), rexec(3), rexecd(8), rlogind(8), rshd(8)
        !           135: .SH DIAGNOSTICS
        !           136: .I Rcmd
        !           137: returns a valid socket descriptor on success.
        !           138: It returns -1 on error and prints a diagnostic message on the standard error.
        !           139: .PP
        !           140: .I Rresvport
        !           141: returns a valid, bound socket descriptor on success.
        !           142: It returns -1 on error with the global value
        !           143: .I errno
        !           144: set according to the reason for failure.
        !           145: The error code EAGAIN is overloaded to mean ``All network ports in use.''

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