usr/src/lib/libc/net/rcmd.3

.\" Copyright (c) 1983 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms are permitted
.\" provided that the above copyright notice and this paragraph are
.\" duplicated in all such forms and that any documentation,
.\" advertising materials, and other materials related to such
.\" distribution and use acknowledge that the software was developed
.\" by the University of California, Berkeley.  The name of the
.\" University may not be used to endorse or promote products derived
.\" from this software without specific prior written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
.\" WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.\"	@(#)rcmd.3	6.9 (Berkeley) %G%
.\"
.TH RCMD 3 ""
.UC 5
.SH NAME
rcmd, rresvport, ruserok \- routines for returning a stream to a remote command
.SH SYNOPSIS
.nf
.PP
.B "rem = rcmd(ahost, inport, locuser, remuser, cmd, fd2p);"
.B char **ahost;
.B int inport;
.B "char *locuser, *remuser, *cmd;"
.B int *fd2p;
.PP
.B s = rresvport(port);
.B int *port;
.PP
.B "ruserok(rhost, superuser, ruser, luser);"
.B char *rhost;
.B int superuser;
.B char *ruser, *luser;
.fi
.SH DESCRIPTION
.I Rcmd
is a routine used by the super-user to execute a command on
a remote machine using an authentication scheme based
on reserved port numbers.
.I Rresvport
is a routine which returns a descriptor to a socket
with an address in the privileged port space.
.I Ruserok
is a routine used by servers
to authenticate clients requesting service with
.IR rcmd .
All three functions are present in the same file and are used
by the
.IR rshd (8)
server (among others).
.PP
.I Rcmd
looks up the host
.I *ahost
using
.IR gethostbyname (3),
returning \-1 if the host does not exist.
Otherwise
.I *ahost
is set to the standard name of the host
and a connection is established to a server
residing at the well-known Internet port
.IR inport .
.PP
If the connection succeeds,
a socket in the Internet domain of type SOCK_STREAM
is returned to the caller, and given to the remote
command as
.B stdin
and
.BR stdout .
If
.I fd2p
is non-zero, then an auxiliary channel to a control
process will be set up, and a descriptor for it will be placed
in
.IR *fd2p .
The control process will return diagnostic
output from the command (unit 2) on this channel, and will also
accept bytes on this channel as being UNIX signal numbers, to be
forwarded to the process group of the command.
If
.I fd2p
is 0, then the
.B stderr
(unit 2 of the remote
command) will be made the same as the
.B stdout
and no
provision is made for sending arbitrary signals to the remote process,
although you may be able to get its attention by using out-of-band data.
.PP
The protocol is described in detail in
.IR rshd (8).
.PP
The
.I rresvport
routine is used to obtain a socket with a privileged
address bound to it.  This socket is suitable for use
by
.I rcmd
and several other routines.  Privileged Internet ports are those
in the range 0 to 1023.  Only the super-user
is allowed to bind an address of this sort to a socket.
.PP
.I Ruserok
takes a remote host's name, as returned by the
.IR gethostbyaddr (3)
routine, two user names and a flag indicating whether
the local user's name is that of the super-user.  Then,
if the user is
.B NOT
the super-user, it checks the files
.IR /etc/hosts.equiv .
If that lookup is not done, or is unsuccessful, the
.I .rhosts
in the local user's home directory is checked to see if the request for
service is allowed.  If this file is owned by anyone other than the
user or the super-user, or if it is writeable by anyone other than the
owner, the check automatically fails.  A 0 is returned if the machine
name is listed in the ``hosts.equiv'' file, or the host and remote
user name are found in the ``.rhosts'' file; otherwise
.I ruserok
returns \-1.
If the local domain (as obtained from \fIgethostname\fP\|(2))
is the same as the remote domain, only the machine name need be specified.
.SH SEE ALSO
rlogin(1), rsh(1), intro(2), rexec(3), rexecd(8), rlogind(8), rshd(8)
.SH DIAGNOSTICS
.I Rcmd
returns a valid socket descriptor on success.
It returns -1 on error and prints a diagnostic message on the standard error.
.PP
.I Rresvport
returns a valid, bound socket descriptor on success.
It returns -1 on error with the global value
.I errno
set according to the reason for failure.
The error code EAGAIN is overloaded to mean ``All network ports in use.''
Commit	Line	Data
	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
	5	.\" provided that the above copyright notice and this paragraph are
	6	.\" duplicated in all such forms and that any documentation,
	7	.\" advertising materials, and other materials related to such
	8	.\" distribution and use acknowledge that the software was developed
	9	.\" by the University of California, Berkeley. The name of the
	10	.\" University may not be used to endorse or promote products derived
	11	.\" from this software without specific prior written permission.
	12	.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
	13	.\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
	14	.\" WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
	15	.\"
	16	.\" @(#)rcmd.3 6.9 (Berkeley) %G%
	17	.\"
	18	.TH RCMD 3 ""
	19	.UC 5
	20	.SH NAME
	21	rcmd, rresvport, ruserok \- routines for returning a stream to a remote command
	22	.SH SYNOPSIS
	23	.nf
	24	.PP
	25	.B "rem = rcmd(ahost, inport, locuser, remuser, cmd, fd2p);"
	26	.B char **ahost;
	27	.B int inport;
	28	.B "char locuser, remuser, *cmd;"
	29	.B int *fd2p;
	30	.PP
	31	.B s = rresvport(port);
	32	.B int *port;
	33	.PP
	34	.B "ruserok(rhost, superuser, ruser, luser);"
	35	.B char *rhost;
	36	.B int superuser;
	37	.B char ruser, luser;
	38	.fi
	39	.SH DESCRIPTION
	40	.I Rcmd
	41	is a routine used by the super-user to execute a command on
	42	a remote machine using an authentication scheme based
	43	on reserved port numbers.
	44	.I Rresvport
	45	is a routine which returns a descriptor to a socket
	46	with an address in the privileged port space.
	47	.I Ruserok
	48	is a routine used by servers
	49	to authenticate clients requesting service with
	50	.IR rcmd .
	51	All three functions are present in the same file and are used
	52	by the
	53	.IR rshd (8)
	54	server (among others).
	55	.PP
	56	.I Rcmd
	57	looks up the host
	58	.I *ahost
	59	using
	60	.IR gethostbyname (3),
	61	returning \-1 if the host does not exist.
	62	Otherwise
	63	.I *ahost
	64	is set to the standard name of the host
	65	and a connection is established to a server
	66	residing at the well-known Internet port
	67	.IR inport .
	68	.PP
	69	If the connection succeeds,
	70	a socket in the Internet domain of type SOCK_STREAM
	71	is returned to the caller, and given to the remote
	72	command as
	73	.B stdin
	74	and
	75	.BR stdout .
	76	If
	77	.I fd2p
	78	is non-zero, then an auxiliary channel to a control
	79	process will be set up, and a descriptor for it will be placed
	80	in
	81	.IR *fd2p .
	82	The control process will return diagnostic
	83	output from the command (unit 2) on this channel, and will also
	84	accept bytes on this channel as being UNIX signal numbers, to be
	85	forwarded to the process group of the command.
	86	If
	87	.I fd2p
	88	is 0, then the
	89	.B stderr
	90	(unit 2 of the remote
	91	command) will be made the same as the
	92	.B stdout
	93	and no
	94	provision is made for sending arbitrary signals to the remote process,
	95	although you may be able to get its attention by using out-of-band data.
	96	.PP
	97	The protocol is described in detail in
	98	.IR rshd (8).
	99	.PP
	100	The
	101	.I rresvport
	102	routine is used to obtain a socket with a privileged
	103	address bound to it. This socket is suitable for use
	104	by
	105	.I rcmd
	106	and several other routines. Privileged Internet ports are those
	107	in the range 0 to 1023. Only the super-user
	108	is allowed to bind an address of this sort to a socket.
	109	.PP
	110	.I Ruserok
	111	takes a remote host's name, as returned by the
	112	.IR gethostbyaddr (3)
	113	routine, two user names and a flag indicating whether
	114	the local user's name is that of the super-user. Then,
	115	if the user is
	116	.B NOT
	117	the super-user, it checks the files
	118	.IR /etc/hosts.equiv .
	119	If that lookup is not done, or is unsuccessful, the
	120	.I .rhosts
	121	in the local user's home directory is checked to see if the request for
	122	service is allowed. If this file is owned by anyone other than the
	123	user or the super-user, or if it is writeable by anyone other than the
	124	owner, the check automatically fails. A 0 is returned if the machine
	125	name is listed in the ``hosts.equiv'' file, or the host and remote
	126	user name are found in the ``.rhosts'' file; otherwise
	127	.I ruserok
	128	returns \-1.
	129	If the local domain (as obtained from \fIgethostname\fP\\|(2))
	130	is the same as the remote domain, only the machine name need be specified.
	131	.SH SEE ALSO
	132	rlogin(1), rsh(1), intro(2), rexec(3), rexecd(8), rlogind(8), rshd(8)
	133	.SH DIAGNOSTICS
	134	.I Rcmd
	135	returns a valid socket descriptor on success.
	136	It returns -1 on error and prints a diagnostic message on the standard error.
	137	.PP
	138	.I Rresvport
	139	returns a valid, bound socket descriptor on success.
	140	It returns -1 on error with the global value
	141	.I errno
	142	set according to the reason for failure.
	143	The error code EAGAIN is overloaded to mean ``All network ports in use.''