mount_portalfs(8)

NAME

mount_portalfs - mount the portal daemon

mount_portalfs [-o options] /etc/portal.conf mount_point

The mount_portalfs utility attaches an instance of the por
tal daemon to the global file system namespace. The conventional mount
point is /p. This command is normally executed by mount(8) at boot time.
The options are as follows:
-o Options are specified with a -o flag followed by a
comma sepa: rated string of options. See the mount(8) man page; for possible
options and their meanings.
The portal daemon provides an 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.
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 de
scriptor back to the calling process as the result of the open system
call.

By convention, the portal daemon divides the namespace into
sub-namespaces, each of which handles objects of a particular type.
The following sub-namespaces are currently implemented: fs,
pipe, tcp, and tcplisten.
The 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.
The 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 pipe namespace will receive their input from the com
mand's standard output; files opened for writing will send the data of
write operations to the command's standard input.
The tcp namespace takes a slash separated hostname and a
port and creates an open TCP/IP connection.
The 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 getsockname(2) with the returned file
descriptor. Privileged ports can only be bound to by the super-user.

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 ig
nored. Blank lines are ignored.
The first field is a pathname prefix to match against the
requested pathname. If a match is found, the second field tells the dae
mon what type of object to create. Subsequent fields are passed to the
creation function.
# @(#)portal.conf 5.1 (Berkeley) 7/13/92 tcplisten/ tcplisten tcplisten/ tcp/ tcp tcp/ fs/ file fs/ pipe/ pipe pipe/

/p/*

Display the greeting of the FreeBSD SMTP server.: head -1 /p/tcp/mx1.freebsd.org/smtp
Implement a (single-threaded) echo server:: while :
do
(exec 3<>/p/tcplisten/ANY/echo && cat -u <&3 >&3); done
Gather data from two sources. Verify that two remote files
are identical:: diff -q '/p/pipe/usr/bin/fetch -o; ftp://ftp1.freebsd.org/pub/FreeBSD/README.TXT' sd.org/pub/FreeB; SD/README.TXT'
Scatter data to two sinks. Record a remote CD ISO image and
calculate its checksum:: fetch -o - ftp://ftp5.freebsd.org/.../disc.iso
tee '/p/pipe/usr/local/bin/cdrecord -'
md5
Create an XML view of the password file:: ln -s '/p/pipe/usr/local/bin/passwd2xml /etc/passwd'; /etc/passwd.xml"

This file system may not be NFS-exported.