path: root/usr.sbin/mount_portalfs/mount_portalfs.8

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.\" Jan-Simon Pendry.
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.\"	@(#)mount_portal.8	8.3 (Berkeley) 3/27/94
.\" $FreeBSD$
.\"
.Dd March 11, 2005
.Dt MOUNT_PORTALFS 8
.Os
.Sh NAME
.Nm mount_portalfs
.Nd mount the portal daemon
.Sh SYNOPSIS
.Nm
.Op Fl o Ar options
.Ar /etc/portal.conf
.Ar mount_point
.Sh DESCRIPTION
The
.Nm
utility attaches an instance of the portal daemon
to the global file system 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 file system 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 fs ,
.Pa pipe ,
.Pa tcp ,
and
.Pa tcplisten .
.Pp
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.
.Pp
The
.Pa pipe
namespace executes the named command, starting back at the root directory.
The command's arguments can be provided after the command's name,
by separating them with spaces or tabs.
Files opened for reading in the
.Pa pipe
namespace will receive their input from the command's standard output;
files opened for writing will send the data of write operations
to the command's standard input.
.Pp
The
.Pa tcp
namespace takes a slash separated hostname and a port and
creates an open TCP/IP connection.
.Pp
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 2
with the returned file descriptor.
Privileged ports can only be bound to
by the super-user.
.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/
pipe/		pipe pipe/
.Ed
.Sh FILES
.Bl -tag -width /p/* -compact
.It Pa /p/*
.El
.Sh EXAMPLES
Display the greeting of the
.Fx
.Tn SMTP
server.
.Pp
.Dl "head -1 /p/tcp/mx1.freebsd.org/smtp"
.Pp
Implement a (single-threaded) echo server:
.Bd -literal -offset indent
while :
do
    (exec 3<>/p/tcplisten/ANY/echo && cat -u <&3 >&3)
done
.Ed
.Pp
Gather data from two sources.
Verify that two remote files are identical:
.Bd -literal -offset indent
diff -q '/p/pipe/usr/bin/fetch -o - \\
        ftp://ftp1.freebsd.org/pub/FreeBSD/README.TXT' \\
    '/p/pipe/usr/bin/fetch -o - \\
        ftp://ftp2.freebsd.org/pub/FreeBSD/README.TXT'
.Ed
.Pp
Scatter data to two sinks.
Record a remote
.Tn CD
.Tn ISO
image and calculate its checksum:
.Bd -literal -offset indent
fetch -o - ftp://ftp5.freebsd.org/.../disc.iso |
tee '/p/pipe/usr/local/bin/cdrecord -' |
md5
.Ed
.Pp
Create an
.Tn XML
view of the password file:
.Bd -literal -offset indent
ln -s '/p/pipe/usr/local/bin/passwd2xml /etc/passwd' \\
    /etc/passwd.xml"
.Ed
.Sh SEE ALSO
.Xr mount 2 ,
.Xr unmount 2 ,
.Xr fstab 5 ,
.Xr mount 8
.Rs
.%A "W. Richard Stevens"
.%A "Jan-Simon Pendry"
.%T "Portals in 4.4BSD"
.%B "USENIX 1995 Technical Conference Proceedings"
.%O "Berkeley, CA"
.%I "Peter Honeyman"
.Re
.Sh CAVEATS
This file system may not be NFS-exported.
.Sh HISTORY
The
.Nm
utility first appeared in
.Bx 4.4 .