299 lines
8.3 KiB
Groff
299 lines
8.3 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" From: @(#)rcmd.3 8.1 (Berkeley) 6/4/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd March 3, 2000
|
|
.Dt RCMD 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm rcmd ,
|
|
.Nm rresvport ,
|
|
.Nm iruserok ,
|
|
.Nm ruserok ,
|
|
.Nm rcmd_af ,
|
|
.Nm rresvport_af ,
|
|
.Nm iruserok_sa
|
|
.Nd routines for returning a stream to a remote command
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.Fd #include <unistd.h>
|
|
.Ft int
|
|
.Fn rcmd "char **ahost" "int inport" "const char *locuser" "const char *remuser" "const char *cmd" "int *fd2p"
|
|
.Ft int
|
|
.Fn rresvport "int *port"
|
|
.Ft int
|
|
.Fn iruserok "u_long raddr" "int superuser" "const char *ruser" "const char *luser"
|
|
.Ft int
|
|
.Fn ruserok "const char *rhost" "int superuser" "const char *ruser" "const char *luser"
|
|
.Ft int
|
|
.Fn rcmd_af "char **ahost" "int inport" "const char *locuser" "const char *remuser" "const char *cmd" "int *fd2p" "int af"
|
|
.Ft int
|
|
.Fn rresvport_af "int *port" "int af"
|
|
.Ft int
|
|
.Fn iruserok_sa "const void *addr" "int addrlen" "int superuser" "const char *ruser" "const char *luser"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn rcmd
|
|
function
|
|
is used by the super-user to execute a command on
|
|
a remote machine using an authentication scheme based
|
|
on reserved port numbers.
|
|
The
|
|
.Fn rresvport
|
|
function
|
|
returns a descriptor to a socket
|
|
with an address in the privileged port space.
|
|
The
|
|
.Fn ruserok
|
|
function
|
|
is used by servers
|
|
to authenticate clients requesting service with
|
|
.Fn rcmd .
|
|
All three functions are present in the same file and are used
|
|
by the
|
|
.Xr rshd 8
|
|
server (among others).
|
|
.Pp
|
|
The
|
|
.Fn rcmd
|
|
function
|
|
looks up the host
|
|
.Fa *ahost
|
|
using
|
|
.Xr gethostbyname 3 ,
|
|
returning -1 if the host does not exist.
|
|
Otherwise
|
|
.Fa *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
|
|
.Fa inport .
|
|
.Pp
|
|
If the connection succeeds,
|
|
a socket in the Internet domain of type
|
|
.Dv SOCK_STREAM
|
|
is returned to the caller, and given to the remote
|
|
command as
|
|
.Em stdin
|
|
and
|
|
.Em stdout .
|
|
If
|
|
.Fa 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
|
|
.Fa *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
|
|
.Tn UNIX
|
|
signal numbers, to be
|
|
forwarded to the process group of the command.
|
|
If
|
|
.Fa fd2p
|
|
is 0, then the
|
|
.Em stderr
|
|
(unit 2 of the remote
|
|
command) will be made the same as the
|
|
.Em 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
|
|
.Xr rshd 8 .
|
|
.Pp
|
|
The
|
|
.Fn rresvport
|
|
function is used to obtain a socket to which an address with a Privileged
|
|
Internet port is bound.
|
|
This socket is suitable for use by
|
|
.Fn rcmd
|
|
and several other functions.
|
|
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
|
|
The
|
|
.Fn iruserok
|
|
and
|
|
.Fn ruserok
|
|
functions take a remote host's IP address or name, as returned by the
|
|
.Xr gethostbyname 3
|
|
routines, two user names and a flag indicating whether the local user's
|
|
name is that of the super-user.
|
|
Then, if the user is
|
|
.Em NOT
|
|
the super-user, it checks the
|
|
.Pa /etc/hosts.equiv
|
|
file.
|
|
If that lookup is not done, or is unsuccessful, the
|
|
.Pa .rhosts
|
|
in the local user's home directory is checked to see if the request for
|
|
service is allowed.
|
|
.Pp
|
|
If this file does not exist, is not a regular file, is owned by anyone
|
|
other than the user or the super-user, or is writable by anyone other
|
|
than the owner, the check automatically fails.
|
|
Zero is returned if the machine name is listed in the
|
|
.Dq Pa hosts.equiv
|
|
file, or the host and remote user name are found in the
|
|
.Dq Pa .rhosts
|
|
file; otherwise
|
|
.Fn iruserok
|
|
and
|
|
.Fn ruserok
|
|
return -1.
|
|
If the local domain (as obtained from
|
|
.Xr gethostname 3 )
|
|
is the same as the remote domain, only the machine name need be specified.
|
|
.Pp
|
|
The
|
|
.Fn iruserok
|
|
function is strongly preferred for security reasons.
|
|
It requires trusting the local DNS at most, while the
|
|
.Fn ruserok
|
|
function requires trusting the entire DNS, which can be spoofed.
|
|
.Pp
|
|
The functions with an
|
|
.Dq Li _af
|
|
or
|
|
.Dq Li _sa
|
|
suffix, i.e.,
|
|
.Fn rcmd_af ,
|
|
.Fn rresvport_af
|
|
and
|
|
.Fn iruserok_sa ,
|
|
work the same as the corresponding functions without a
|
|
suffix, except that they are capable of handling both IPv6 and IPv4 ports.
|
|
.Pp
|
|
The
|
|
.Dq Li _af
|
|
suffix means that the function has an additional
|
|
.Fa af
|
|
argument which is used to specify the address family,
|
|
(see below).
|
|
The
|
|
.Fa af
|
|
argument extension is implemented for functions
|
|
that have no binary address argument.
|
|
Instead, the
|
|
.Fa af
|
|
argument specifies which address family is desired.
|
|
.Pp
|
|
The
|
|
.Dq Li _sa
|
|
suffix means that the function has general socket address and
|
|
length arguments.
|
|
As the socket address is a protocol independent data structure,
|
|
IPv4 and IPv6 socket address can be passed as desired.
|
|
The
|
|
.Fa sa
|
|
argument extension is implemented for functions
|
|
that pass a protocol dependent binary address argument.
|
|
The argument needs to be replaced with a more general address structure
|
|
to support multiple address families in a general way.
|
|
.Pp
|
|
The functions with neither an
|
|
.Dq Li _af
|
|
suffix nor an
|
|
.Dq Li _sa
|
|
suffix work for IPv4 only, except for
|
|
.Fn ruserok
|
|
which can handle both IPv6 and IPv4.
|
|
To switch the address family, the
|
|
.Fa af
|
|
argument must be filled with
|
|
.Dv AF_INET ,
|
|
or
|
|
.Dv AF_INET6 .
|
|
For
|
|
.Fn rcmd_af ,
|
|
.Dv PF_UNSPEC
|
|
is also allowed.
|
|
.Sh DIAGNOSTICS
|
|
The
|
|
.Fn rcmd
|
|
function
|
|
returns a valid socket descriptor on success.
|
|
It returns -1 on error and prints a diagnostic message
|
|
on the standard error.
|
|
.Pp
|
|
The
|
|
.Fn rresvport
|
|
function
|
|
returns a valid, bound socket descriptor on success.
|
|
It returns -1 on error with the global value
|
|
.Va errno
|
|
set according to the reason for failure.
|
|
The error code
|
|
.Er EAGAIN
|
|
is overloaded to mean ``All network ports in use.''
|
|
.Sh SEE ALSO
|
|
.Xr rlogin 1 ,
|
|
.Xr rsh 1 ,
|
|
.Xr intro 2 ,
|
|
.Xr rexec 3 ,
|
|
.Xr rexecd 8 ,
|
|
.Xr rlogind 8 ,
|
|
.Xr rshd 8
|
|
.Pp
|
|
.Rs
|
|
.%A W. Stevens
|
|
.%A M. Thomas
|
|
.%T "Advanced Socket API for IPv6"
|
|
.%O RFC2292
|
|
.Re
|
|
.Rs
|
|
.%A W. Stevens
|
|
.%A M. Thomas
|
|
.%A E. Nordmark
|
|
.%T "Advanced Socket API for IPv6"
|
|
.%O draft-ietf-ipngwg-rfc2292bis-01.txt
|
|
.Re
|
|
.Sh HISTORY
|
|
Most of these
|
|
functions appeared in
|
|
.Bx 4.2 .
|
|
.Fn rresvport_af
|
|
appeared in RFC2292, and was implemented by the WIDE project
|
|
for the Hydrangea IPv6 protocol stack kit.
|
|
.Fn rcmd_af
|
|
appeared in draft-ietf-ipngwg-rfc2292bis-01.txt,
|
|
and was implemented in the WIDE/KAME IPv6 protocol stack kit.
|
|
.Fn iruserok_sa
|
|
appeared in discussion on the IETF ipngwg mailing list,
|
|
and was implemented in
|
|
.Fx 4.0 .
|