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1 | .\" Copyright (c) 1983 The Regents of the University of California. |
2 | .\" All rights reserved. | |
11a95b5f | 3 | .\" |
1c15e888 C |
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. | |
d20a1e6f | 17 | .\" |
1c15e888 | 18 | .\" @(#)rcmd.3 6.10 (Berkeley) 6/23/90 |
11a95b5f | 19 | .\" |
1c15e888 | 20 | .TH RCMD 3 "June 23, 1990" |
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21 | .UC 5 |
22 | .SH NAME | |
23 | rcmd, rresvport, ruserok \- routines for returning a stream to a remote command | |
24 | .SH SYNOPSIS | |
25 | .nf | |
4fb1c171 | 26 | .PP |
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27 | .B "rem = rcmd(ahost, inport, locuser, remuser, cmd, fd2p);" |
28 | .B char **ahost; | |
f3f0480d | 29 | .B int inport; |
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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 | |
d20a1e6f | 55 | .IR rshd (8) |
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56 | server (among others). |
57 | .PP | |
58 | .I Rcmd | |
59 | looks up the host | |
60 | .I *ahost | |
61 | using | |
d20a1e6f | 62 | .IR gethostbyname (3), |
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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 | |
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71 | If the connection succeeds, |
72 | a socket in the Internet domain of type SOCK_STREAM | |
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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 | |
d20a1e6f | 100 | .IR rshd (8). |
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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 | |
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108 | and several other routines. Privileged Internet ports are those |
109 | in the range 0 to 1023. Only the super-user | |
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110 | is allowed to bind an address of this sort to a socket. |
111 | .PP | |
112 | .I Ruserok | |
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113 | takes a remote host's name, as returned by the |
114 | .IR gethostbyaddr (3) | |
7faf4e1f | 115 | routine, two user names and a flag indicating whether |
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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 | |
11a95b5f | 122 | .I .rhosts |
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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 | |
11a95b5f | 129 | .I ruserok |
d20a1e6f | 130 | returns \-1. |
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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. | |
11a95b5f | 133 | .SH SEE ALSO |
d20a1e6f | 134 | rlogin(1), rsh(1), intro(2), rexec(3), rexecd(8), rlogind(8), rshd(8) |
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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.'' |