term% cat index.txt IMPORT(4) Kernel Interfaces Manual IMPORT(4)
NAME
import - import a name space from a remote system
SYNOPSIS
import [ options ] system file [ mountpoint ]
import -m [ options ] system mountpoint
import -B [ options ] mountpoint [ cmd [ args ... ] ]
DESCRIPTION
Import allows an arbitrary file on a remote system to be imported into
the local name space. Usually file is a directory, so the complete
file tree under the directory is made available.
A process is started on the remote machine, with authority of the user
of import, to perform work for the local machine using the exportfs(4)
service. The default port used is TCP 17007. If mountpoint is omitted
import uses the name of the remote file as the local mount point.
The options are:
-a -b -c -C
Control the construction of union directories, as in mount and
bind(1). Only valid when file is a directory.
-A Skip the authentication protocol. This is useful for connecting
to foreign systems like Inferno.
-B Run in ``backwards'' mode, described below.
-E enc Push an authentication protocol on its network connection. The
supported protocols are clear (the default, no protocol) and
ssl. There are plans to make tls available.
-e 'enc auth'
Specify the encryption and authentication algorithms to use for
encrypting the wire traffic (see ssl(3)). The defaults are
rc4_256 and sha1.
-k keypattern
Use keypattern to select a key to authenticate to the remote
side (see auth(2)).
-o -O These equivalent flags run import in a pre-9P2000 compatibility
mode to import from ancient servers.
-p Push the aan(8) filter onto the connection to protect against
temporary network outages.
-s name
Post the connection's mountable file descriptor as /srv/name.
The -m option mounts a file exported by exportfs(4) with its -r or -S
options, which skip the part of its protocol that allows the importer
to specify the file to export. Instead, the file or name space is se‐
lected by exportfs, and import mounts it on mountpoint as guided by the
other options.
The -B option runs import in ``backwards'' mode. In this mode, import
runs a p9any authentication (as server) over its file descriptor 0 (ex‐
pected to be an incoming network connection from exportfs -B), mounts
the connection onto mntpt, and optionally runs cmd args.
EXAMPLES
Assume a machine kremvax that has IP interfaces for the company in‐
tranet and the global internet mounted on /net and /net.alt respec‐
tively. Any machine inside the company can get telnet out to the
global internet using:
import -a kremvax /net.alt
telnet /net.alt/tcp!ucbvax
Suppose that the machine moscvax has access to a private file server
containing public web pages that need to be served by the less-trusted
server webvax. Webvax runs the following listener (see listen(8)) on
TCP port 999:
#!/bin/rc
import -B -s rowebfs /usr/web /bin/restarthttpd
When moscvax boots, it runs
exportfs -R -r /usr/web -B tcp!webvax!999
to serve a read-only copy of /usr/web to webvax. When webvax gets the
call, import mounts the served tree onto its own /usr/web and then runs
/bin/restarthttpd to restart httpd(8).
SOURCE
/sys/src/cmd/import.c
SEE ALSO
bind(1), ssl(3), exportfs(4), srv(4), aan(8), listen(8), cs in ndb(8)
IMPORT(4)