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.TH IMPORT 4

.SH NAME

import \- import a name space from a remote system

.SH SYNOPSIS

.B import

[

.I options

]

.I system

.I file

[

.I mountpoint

]

.PP

.B import

.B -m

[

.I options

]

.I system

.I mountpoint

.PP

.B import

.B -B

[

.I options

]

.I mountpoint

[

.I cmd

[

.I args ...

]

]

.SH DESCRIPTION

.I Import

allows an arbitrary

.I file

on a remote

.I system

to be imported into the local name space.

Usually

.I file

is a directory, so the complete

file tree under the directory is made available.

.PP

A process is started on the

remote machine, with authority of the user of

.IR import ,

to perform work for the local machine using the

.IR exportfs (4)

service.

The default port used is TCP 17007.

If

.I mountpoint

is omitted

.I import

uses the name of the remote

.I file

as the local mount point.

.PP

The options are:

.TF "-s namexxx"

.PD

.TP

.B -a -b -c -C

Control the construction of union directories, as in

.I mount

and

.IR bind (1).

Only valid when 

.I file

is a directory.

.TP

.B -A

Skip the authentication protocol.

This is useful for connecting to foreign systems like Inferno.

.TP

.B -B

Run in ``backwards'' mode, described below.

.TP

.B -E \fIenc

Push an authentication protocol on its network connection.

The supported protocols are

.B clear

(the default, no protocol)

and

.BR ssl .

There are plans to make

.B tls

available.

.TP

.B -e '\fIenc auth\fR'

Specify the encryption and authentication algorithms to use for

encrypting the wire traffic

(see

.IR ssl (3)).

The defaults are

.B rc4_256

and

.BR sha1 .

.TP

.B -k \fIkeypattern

Use

.I keypattern

to select a key to authenticate to the remote side

(see

.IR auth (2)).

.TP

.B -o -O

These equivalent flags run

.I import

in a pre-9P2000 compatibility mode to import from ancient servers.

.TP

.B -p

Push the

.IR aan (8)

filter onto the connection to protect against

temporary network outages.

.TP

.B -s \fIname

Post the connection's mountable file descriptor as

.BI /srv/ name\fR.

.PD

.PP

The

.B -m

option mounts a file exported by

.IR exportfs (4)

with its

.B -r

or

.B -S

options, which skip the part of its protocol that allows the importer to specify

the

.I file

to export.

Instead, the file or name space is selected by

.IR exportfs ,

and

.I import

mounts it on

.I mountpoint

as guided by the other

.IR options .

.PP

The 

.B -B

option runs

.I import

in ``backwards'' mode.

In this mode,

.I import

runs a

.I p9any

authentication (as server) over its file descriptor 0

(expected to be an incoming network connection from

.B exportfs

.BR -B ),

mounts the connection onto

.IR mntpt ,

and optionally runs

.I cmd

.IR args .

.SH EXAMPLES

Assume a machine

.B kremvax

that has IP interfaces for the company intranet and the global

internet mounted on

.I /net

and

.I /net.alt

respectively.

Any machine inside the company can get telnet out to the global

internet using:

.IP

.EX

import -a kremvax /net.alt

telnet /net.alt/tcp!ucbvax

.EE

.PP

Suppose that the machine

.B moscvax

has access to a private file server containing public web pages

that need to be served by the less-trusted server

.BR webvax .

.B Webvax

runs the following listener 

(see

.IR listen (8))

on TCP port 999:

.IP

.EX

#!/bin/rc

import -B -s rowebfs /usr/web /bin/restarthttpd

.EE

.PP

When

.B moscvax

boots, it runs

.IP

.EX

exportfs -R -r /usr/web -B tcp!webvax!999

.EE

.PP

to serve a read-only copy of

.B /usr/web

to

.BR webvax .

When

.B webvax

gets the call, 

.B import

mounts the served tree onto its own

.B /usr/web

and then runs

.B /bin/restarthttpd

to restart

.IR httpd (8).

.SH SOURCE

.B /sys/src/cmd/import.c

.SH SEE ALSO

.IR bind (1),

.IR ssl (3),

.IR exportfs (4),

.IR srv (4),

.IR aan (8),

.IR listen (8),

.B cs

in

.IR ndb (8)