.\"
.\" Copyright (c) 1993, 1994
.\"	The Regents of the University of California.  All rights reserved.
.\" All rights reserved.
.\"
.\" This code is derived from software donated to Berkeley by
.\" Jan-Simon Pendry.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer in the
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.\"    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.
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.\"	@(#)mount_portal.8	8.3 (Berkeley) 3/27/94
.\"	$Id: mount_portal.8,v 1.4 1998/12/15 18:59:06 dillon Exp $
.\"
.Dd March 27, 1994
.Dt MOUNT_PORTAL 8
.Os BSD 4.4
.Sh NAME
.Nm mount_portal
.Nd mount the portal daemon
.Sh SYNOPSIS
.Nm mount_portal
.Op Fl o Ar options
.Ar /etc/portal.conf
.Ar mount_point
.Sh DESCRIPTION
The
.Nm
command attaches an instance of the portal daemon
to the global filesystem namespace.
The conventional mount point is
.Pa /p .
.\" .PA /dev .
This command is normally executed by
.Xr mount 8
at boot time.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl o
Options are specified with a
.Fl o
flag followed by a comma separated string of options.
See the
.Xr mount 8
man page for possible options and their meanings.
.El
.Pp
The portal daemon provides an
.Em open
service.
Objects opened under the portal mount point are
dynamically created by the portal daemon according
to rules specified in the named configuration file.
Using this mechanism allows descriptors such as sockets
to be made available in the filesystem namespace.
.Pp
The portal daemon works by being passed the full pathname
of the object being opened.
The daemon creates an appropriate descriptor according
to the rules in the configuration file, and then passes the descriptor back
to the calling process as the result of the open system call.
.Sh NAMESPACE
By convention, the portal daemon divides the namespace into sub-namespaces,
each of which handles objects of a particular type.
.Pp
The following sub-namespaces are currently implemented:
.Pa tcplisten ,
.Pa tcp
and
.Pa fs .
The
.Pa tcplisten
namespace takes a slash separated hostname and port and creates a TCP/IP
socket bound to the given hostname-port pair. The hostname may be
specified as "ANY" to allow any other host to connect to the socket. A
port number of 0 will dynamically allocate a port, this can be
discovered by calling
.Xr getsockname 8
with the returned file descriptor. Privileged ports can only be bound to
by the super-user.
The
.Pa tcp
namespace takes a hostname and a port (slash separated) and
creates an open TCP/IP connection.
The
.Pa fs
namespace opens the named file, starting back at the root directory.
This can be used to provide a controlled escape path from
a chrooted environment.
.Sh "CONFIGURATION FILE"
The configuration file contains a list of rules.
Each rule takes one line and consists of two or more
whitespace separated fields.
A hash (``#'') character causes the remainder of a line to
be ignored.  Blank lines are ignored.
.Pp
The first field is a pathname prefix to match
against the requested pathname.
If a match is found, the second field
tells the daemon what type of object to create.
Subsequent fields are passed to the creation function.
.Bd -literal
# @(#)portal.conf	5.1 (Berkeley) 7/13/92
tcplisten/	tcplisten tcplisten/
tcp/		tcp tcp/
fs/		file fs/
.Ed
.Sh FILES
.Bl -tag -width /p/* -compact
.It Pa /p/*
.El
.Sh SEE ALSO
.Xr mount 2 ,
.Xr unmount 2 ,
.Xr fstab 5 ,
.Xr mount 8
.Sh CAVEATS
This filesystem may not be NFS-exported.
.Sh HISTORY
The
.Nm
utility first appeared in
.Bx 4.4 .