| [9] | 1 | .\" Copyright (c) 1983 Regents of the University of California.
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| 2 | .\" All rights reserved. The Berkeley software License Agreement
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| 3 | .\" specifies the terms and conditions for redistribution.
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| 4 | .\"
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| 5 | .\" @(#)rcmd.3 6.7 (Berkeley) 5/14/86
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| 6 | .\"
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| 7 | .TH RCMD 3 "May 14, 1986"
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| 8 | .UC 5
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| 9 | .SH NAME
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| 10 | rcmd, rresvport, ruserok \- routines for returning a stream to a remote command
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| 11 | .SH SYNOPSIS
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| 12 | .nf
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| 13 | .B "#include <sys/types.h>"
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| 14 | .B "#include <net/netlib.h>"
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| 15 | .PP
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| 16 | .B "rem = rcmd(ahost, inport, locuser, remuser, cmd, fd2p);"
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| 17 | .B char **ahost;
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| 18 | .B int inport;
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| 19 | .B "char *locuser, *remuser, *cmd;"
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| 20 | .B int *fd2p;
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| 21 | .PP
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| 22 | .B s = rresvport(port);
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| 23 | .B int *port;
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| 24 | .PP
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| 25 | .B "ruserok(rhost, superuser, ruser, luser);"
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| 26 | .B char *rhost;
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| 27 | .B int superuser;
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| 28 | .B char *ruser, *luser;
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| 29 | .fi
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| 30 | .SH DESCRIPTION
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| 31 | .I Rcmd
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| 32 | is a routine used by the super-user to execute a command on
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| 33 | a remote machine using an authentication scheme based
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| 34 | on reserved port numbers.
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| 35 | .I Rresvport
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| 36 | is a routine which returns a descriptor to a socket
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| 37 | with an address in the privileged port space.
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| 38 | .I Ruserok
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| 39 | is a routine used by servers
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| 40 | to authenticate clients requesting service with
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| 41 | .IR rcmd .
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| 42 | All three functions are present in the same file and are used
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| 43 | by the
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| 44 | .IR rshd (8)
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| 45 | server (among others).
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| 46 | .PP
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| 47 | .I Rcmd
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| 48 | looks up the host
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| 49 | .I *ahost
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| 50 | using
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| 51 | .IR gethostbyname (3),
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| 52 | returning \-1 if the host does not exist.
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| 53 | Otherwise
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| 54 | .I *ahost
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| 55 | is set to the standard name of the host
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| 56 | and a connection is established to a server
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| 57 | residing at the well-known Internet port
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| 58 | .IR inport .
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| 59 | .PP
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| 60 | If the connection succeeds,
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| 61 | a socket in the Internet domain of type SOCK_STREAM
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| 62 | is returned to the caller, and given to the remote
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| 63 | command as
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| 64 | .B stdin
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| 65 | and
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| 66 | .BR stdout .
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| 67 | If
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| 68 | .I fd2p
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| 69 | is non-zero, then an auxiliary channel to a control
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| 70 | process will be set up, and a descriptor for it will be placed
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| 71 | in
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| 72 | .IR *fd2p .
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| 73 | The control process will return diagnostic
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| 74 | output from the command (unit 2) on this channel, and will also
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| 75 | accept bytes on this channel as being UNIX signal numbers, to be
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| 76 | forwarded to the process group of the command.
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| 77 | If
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| 78 | .I fd2p
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| 79 | is 0, then the
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| 80 | .B stderr
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| 81 | (unit 2 of the remote
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| 82 | command) will be made the same as the
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| 83 | .B stdout
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| 84 | and no
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| 85 | provision is made for sending arbitrary signals to the remote process,
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| 86 | although you may be able to get its attention by using out-of-band data.
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| 87 | .PP
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| 88 | The protocol is described in detail in
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| 89 | .IR rshd (8).
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| 90 | .PP
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| 91 | The
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| 92 | .I rresvport
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| 93 | routine is used to obtain a socket with a privileged
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| 94 | address bound to it. This socket is suitable for use
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| 95 | by
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| 96 | .I rcmd
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| 97 | and several other routines. Privileged Internet ports are those
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| 98 | in the range 0 to 1023. Only the super-user
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| 99 | is allowed to bind an address of this sort to a socket.
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| 100 | .PP
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| 101 | .I Ruserok
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| 102 | takes a remote host's name, as returned by a
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| 103 | .IR gethostbyaddr (3)
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| 104 | routine, two user names and a flag indicating whether
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| 105 | the local user's name is that of the super-user. It then
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| 106 | checks the files
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| 107 | .I /etc/hosts.equiv
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| 108 | and, possibly,
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| 109 | .I .rhosts
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| 110 | in the current working directory (normally the local
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| 111 | user's home directory) to see if the request for
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| 112 | service is allowed. A 0 is returned if the machine
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| 113 | name is listed in the ``hosts.equiv'' file, or the
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| 114 | host and remote user name are found in the ``.rhosts''
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| 115 | file; otherwise
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| 116 | .I ruserok
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| 117 | returns \-1. If the
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| 118 | .I superuser
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| 119 | flag is 1, the checking of the ``host.equiv'' file is
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| 120 | bypassed.
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| 121 | If the local domain (as obtained from \fIgethostname\fP\|(3))
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| 122 | is the same as the remote domain, only the machine name need be specified.
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| 123 | .SH SEE ALSO
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| 124 | rlogin(1),
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| 125 | rsh(1),
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| 126 | intro(2),
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| 127 | rexec(3),
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| 128 | rexecd(8),
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| 129 | rlogind(8),
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| 130 | rshd(8)
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| 131 | .SH DIAGNOSTICS
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| 132 | .I Rcmd
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| 133 | returns a valid socket descriptor on success.
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| 134 | It returns -1 on error and prints a diagnostic message on the standard error.
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| 135 | .PP
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| 136 | .I Rresvport
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| 137 | returns a valid, bound socket descriptor on success.
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| 138 | It returns -1 on error with the global value
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| 139 | .I errno
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| 140 | set according to the reason for failure.
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| 141 | The error code EAGAIN is overloaded to mean ``All network ports in use.''
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