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Annotation of 43BSDTahoe/man/man3/rcmd.3, revision 1.1

1.1     ! root        1: .\" Copyright (c) 1983 Regents of the University of California.
        !             2: .\" All rights reserved.  The Berkeley software License Agreement
        !             3: .\" specifies the terms and conditions for redistribution.
        !             4: .\"
        !             5: .\"    @(#)rcmd.3      6.8 (Berkeley) 9/30/87
        !             6: .\"
        !             7: .TH RCMD 3 "September 30, 1987"
        !             8: .UC 5
        !             9: .SH NAME
        !            10: rcmd, rresvport, ruserok \- routines for returning a stream to a remote command
        !            11: .SH SYNOPSIS
        !            12: .nf
        !            13: .PP
        !            14: .B "rem = rcmd(ahost, inport, locuser, remuser, cmd, fd2p);"
        !            15: .B char **ahost;
        !            16: .B int inport;
        !            17: .B "char *locuser, *remuser, *cmd;"
        !            18: .B int *fd2p;
        !            19: .PP
        !            20: .B s = rresvport(port);
        !            21: .B int *port;
        !            22: .PP
        !            23: .B "ruserok(rhost, superuser, ruser, luser);"
        !            24: .B char *rhost;
        !            25: .B int superuser;
        !            26: .B char *ruser, *luser;
        !            27: .fi
        !            28: .SH DESCRIPTION
        !            29: .I Rcmd
        !            30: is a routine used by the super-user to execute a command on
        !            31: a remote machine using an authentication scheme based
        !            32: on reserved port numbers.
        !            33: .I Rresvport
        !            34: is a routine which returns a descriptor to a socket
        !            35: with an address in the privileged port space.
        !            36: .I Ruserok
        !            37: is a routine used by servers
        !            38: to authenticate clients requesting service with
        !            39: .IR rcmd .
        !            40: All three functions are present in the same file and are used
        !            41: by the
        !            42: .IR rshd (8C)
        !            43: server (among others).
        !            44: .PP
        !            45: .I Rcmd
        !            46: looks up the host
        !            47: .I *ahost
        !            48: using
        !            49: .IR gethostbyname (3N),
        !            50: returning \-1 if the host does not exist.
        !            51: Otherwise
        !            52: .I *ahost
        !            53: is set to the standard name of the host
        !            54: and a connection is established to a server
        !            55: residing at the well-known Internet port
        !            56: .IR inport .
        !            57: .PP
        !            58: If the connection succeeds,
        !            59: a socket in the Internet domain of type SOCK_STREAM
        !            60: is returned to the caller, and given to the remote
        !            61: command as 
        !            62: .B stdin
        !            63: and
        !            64: .BR stdout .
        !            65: If
        !            66: .I fd2p
        !            67: is non-zero, then an auxiliary channel to a control
        !            68: process will be set up, and a descriptor for it will be placed
        !            69: in
        !            70: .IR *fd2p .
        !            71: The control process will return diagnostic
        !            72: output from the command (unit 2) on this channel, and will also
        !            73: accept bytes on this channel as being UNIX signal numbers, to be
        !            74: forwarded to the process group of the command.
        !            75: If
        !            76: .I fd2p
        !            77: is 0, then the 
        !            78: .B stderr
        !            79: (unit 2 of the remote
        !            80: command) will be made the same as the 
        !            81: .B stdout
        !            82: and no
        !            83: provision is made for sending arbitrary signals to the remote process,
        !            84: although you may be able to get its attention by using out-of-band data.
        !            85: .PP
        !            86: The protocol is described in detail in
        !            87: .IR rshd (8C).
        !            88: .PP
        !            89: The
        !            90: .I rresvport
        !            91: routine is used to obtain a socket with a privileged
        !            92: address bound to it.  This socket is suitable for use
        !            93: by 
        !            94: .I rcmd
        !            95: and several other routines.  Privileged Internet ports are those
        !            96: in the range 0 to 1023.  Only the super-user
        !            97: is allowed to bind an address of this sort to a socket.
        !            98: .PP
        !            99: .I Ruserok
        !           100: takes a remote host's name, as returned by a
        !           101: .IR gethostbyaddr (3N)
        !           102: routine, two user names and a flag indicating whether
        !           103: the local user's name is that of the super-user.  It then
        !           104: checks the files 
        !           105: .I /etc/hosts.equiv
        !           106: and, possibly, 
        !           107: .I .rhosts
        !           108: in the local user's home directory to see if the request for
        !           109: service is allowed.  A 0 is returned if the machine
        !           110: name is listed in the ``hosts.equiv'' file, or the
        !           111: host and remote user name are found in the ``.rhosts''
        !           112: file; otherwise 
        !           113: .I ruserok
        !           114: returns \-1.  If the
        !           115: .I superuser
        !           116: flag is 1, the checking of the ``hosts.equiv'' file is
        !           117: bypassed.
        !           118: If the local domain (as obtained from \fIgethostname\fP\|(2))
        !           119: is the same as the remote domain, only the machine name need be specified.
        !           120: .SH SEE ALSO
        !           121: rlogin(1C),
        !           122: rsh(1C),
        !           123: intro(2),
        !           124: rexec(3),
        !           125: rexecd(8C),
        !           126: rlogind(8C),
        !           127: rshd(8C)
        !           128: .SH DIAGNOSTICS
        !           129: .I Rcmd
        !           130: returns a valid socket descriptor on success.
        !           131: It returns -1 on error and prints a diagnostic message on the standard error.
        !           132: .PP
        !           133: .I Rresvport
        !           134: returns a valid, bound socket descriptor on success.
        !           135: It returns -1 on error with the global value
        !           136: .I errno
        !           137: set according to the reason for failure.
        !           138: The error code EAGAIN is overloaded to mean ``All network ports in use.''

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