Numerous adjustments to the recent rpcbind etc. changes.
[dragonfly.git] / usr.sbin / jail / jail.8
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1.\"
2.\" Copyright (c) 2000 Robert N. M. Watson
3.\" All rights reserved.
4.\"
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6.\" modification, are permitted provided that the following conditions
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10.\" 2. Redistributions in binary form must reproduce the above copyright
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18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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27.\" ----------------------------------------------------------------------------
28.\" "THE BEER-WARE LICENSE" (Revision 42):
29.\" <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
30.\" can do whatever you want with this stuff. If we meet some day, and you think
31.\" this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
32.\" ----------------------------------------------------------------------------
33.\"
34.\" $FreeBSD: src/usr.sbin/jail/jail.8,v 1.13.2.15 2003/05/08 13:04:24 maxim Exp $
8a7bdfea 35.\" $DragonFly: src/usr.sbin/jail/jail.8,v 1.11 2008/05/02 02:05:07 swildner Exp $
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36.\"
37.Dd December 12, 2001
38.Dt JAIL 8
39.Os
40.Sh NAME
41.Nm jail
42.Nd "imprison process and its descendants"
43.Sh SYNOPSIS
44.Nm
61deed49 45.Op Fl i
e8e3f0ad 46.Op Fl l u Ar username | Fl U Ar username
3e4150ef 47.Ar path hostname ip-list command ...
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48.Sh DESCRIPTION
49The
50.Nm
51command imprisons a process and all future descendants.
52.Pp
53The options are as follows:
54.Bl -tag -width ".Fl u Ar username"
61deed49 55.It Fl i
3f5e28f4 56Output the jail identifier of the newly created jail.
e8e3f0ad
VBD
57.It Fl l
58Run program in the clean environment.
59The environment is discarded except for
60.Ev HOME , SHELL , TERM
61and
62.Ev USER .
63.Ev HOME
64and
65.Ev SHELL
66are set to the target login's default values.
67.Ev USER
68is set to the target login.
69.Ev TERM
70is imported from the current environment.
71The environment variables from the login class capability database for the
72target login are also set.
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73.It Fl u Ar username
74The user name as whom the
75.Ar command
76should run.
e8e3f0ad
VBD
77.It Fl U Ar username
78The user name from jailed environment as whom the
0474a71e 79.Ar command
e8e3f0ad 80should run.
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81.It Ar path
82Directory which is to be the root of the prison.
83.It Ar hostname
84Hostname of the prison.
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85.It Ar ip-list
86Comma separated IP list assigned to the prison.
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87.It Ar command
88Pathname of the program which is to be executed.
89.El
90.Pp
91Please see the
92.Xr jail 2
93man page for further details.
94.Sh EXAMPLES
95.Ss "Setting up a Jail Directory Tree"
96This example shows how to setup a jail directory tree
97containing an entire
9bb2a92d 98.Dx
5c1ee908 99distribution, provided that you built world before already:
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100.Bd -literal
101D=/here/is/the/jail
102cd /usr/src
103mkdir -p $D
5c1ee908 104make installworld DESTDIR=$D
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105cd etc
106make distribution DESTDIR=$D -DNO_MAKEDEV_RUN
107cd $D/dev
108sh MAKEDEV jail
109cd $D
110ln -sf dev/null kernel
111.Ed
112.Pp
113In many cases this example would put far more stuff in the jail than is needed.
114In the other extreme case a jail might contain only one single file:
115the executable to be run in the jail.
116.Pp
117We recommend experimentation and caution that it is a lot easier to
118start with a
119.Dq fat
120jail and remove things until it stops working,
121than it is to start with a
122.Dq thin
123jail and add things until it works.
124.Ss "Setting Up a Jail"
125Do what was described in
126.Sx "Setting Up a Jail Directory Tree"
127to build the jail directory tree.
128For the sake of this example, we will
129assume you built it in
130.Pa /data/jail/192.168.11.100 ,
3e4150ef 131named for the external jail IP address.
984263bc 132Substitute below as needed with your
3e4150ef 133own directory, IP addresses, and hostname.
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134.Pp
135First, you will want to set up your real system's environment to be
136.Dq jail-friendly .
137For consistency, we will refer to the parent box as the
138.Dq "host environment" ,
139and to the jailed virtual machine as the
140.Dq "jail environment" .
141Because jail is implemented using IP aliases, one of the first things to do
142is to disable IP services on the host system that listen on all local
143IP addresses for a service.
144This means changing
145.Xr inetd 8
146to only listen on the
147appropriate IP address, and so forth.
148Add the following to
149.Pa /etc/rc.conf
150in the host environment:
151.Bd -literal -offset indent
152sendmail_enable="NO"
153inetd_flags="-wW -a 192.168.11.23"
3b813696 154rpcbind_enable="NO"
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155.Ed
156.Pp
157.Li 192.168.11.23
158is the native IP address for the host system, in this example.
159Daemons that run out of
160.Xr inetd 8
161can be easily set to use only the specified host IP address.
162Other daemons
163will need to be manually configured\(emfor some this is possible through
164the
165.Xr rc.conf 5
166flags entries, for others it is not possible without munging
167the per-application configuration files, or even recompiling.
168For those
169applications that cannot specify the IP they run on, it is better to disable
170them, if possible.
171.Pp
172A number of daemons ship with the base system that may have problems when
173run from outside of a jail in a jail-centric environment.
174This includes
175.Xr sendmail 8 ,
176.Xr named 8 ,
177and
3b813696 178.Xr rpcbind 8 .
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179While
180.Xr sendmail 8
181and
182.Xr named 8
183can be configured to listen only on a specific
184IP using their configuration files, in most cases it is easier to simply
185run the daemons in jails only, and not in the host environment.
186Attempting to serve
187NFS from the host environment may also cause confusion, and cannot be
188easily reconfigured to use only specific IPs, as some NFS services are
189hosted directly from the kernel.
190Any third party network software running
191in the host environment should also be checked and configured so that it
192does not bind all IP addresses, which would result in those services also
193appearing to be offered by the jail environments.
194.Pp
195Once
196these daemons have been disabled or fixed in the host environment, it is
197best to reboot so that all daemons are in a known state, to reduce the
198potential for confusion later (such as finding that when you send mail
199to a jail, and its sendmail is down, the mail is delivered to the host,
200etc.)
201.Pp
202Start any jails for the first time without configuring the network
203interface so that you can clean it up a little and set up accounts.
204As
205with any machine (virtual or not) you will need to set a root password, time
206zone, etc.
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207.Pp
208Now start the jail:
209.Pp
3e4150ef 210.Dl "jail /data/jail/192.168.11.100 testhostname 127.0.0.1,192.168.11.100 /bin/sh"
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211.Pp
212You will end up with a shell prompt, assuming no errors, within the jail.
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213You can now do the post-install configuration to set various configuration
214options by editing
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215.Pa /etc/rc.conf ,
216etc.
217.Pp
218.Bl -bullet -offset indent -compact
219.It
220Create an empty
221.Pa /etc/fstab
222to quell startup warnings about missing fstab
223.It
224Disable the port mapper
225.Pa ( /etc/rc.conf :
3b813696 226.Li rpcbind_enable="NO" )
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227.It
228Run
229.Xr newaliases 1
230to quell
231.Xr sendmail 8
232warnings.
233.It
234Disable interface configuration to quell startup warnings about
235.Xr ifconfig 8
236.Pq Li network_interfaces=""
237.It
238Configure
239.Pa /etc/resolv.conf
240so that name resolution within the jail will work correctly
241.It
242Set a root password, probably different from the real host system
243.It
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244Set the timezone with
245.Xr tzsetup 8
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246.It
247Add accounts for users in the jail environment
248.It
249Install any packages that you think the environment requires
250.El
251.Pp
252You may also want to perform any package-specific configuration (web servers,
253SSH servers, etc), patch up
254.Pa /etc/syslog.conf
255so it logs as you would like, etc.
256.Pp
257Exit from the shell, and the jail will be shut down.
258.Ss "Starting the Jail"
259You are now ready to restart the jail and bring up the environment with
260all of its daemons and other programs.
261To do this, first bring up the
262virtual host interface, and then start the jail's
263.Pa /etc/rc
264script from within the jail.
265.Pp
266NOTE: If you plan to allow untrusted users to have root access inside the
267jail, you may wish to consider setting the
268.Va jail.set_hostname_allowed
269to 0.
270Please see the management reasons why this is a good idea.
271If you do decide to set this variable,
272it must be set before starting any jails, and once each boot.
273.Bd -literal -offset indent
274ifconfig ed0 inet alias 192.168.11.100/32
275mount -t procfs proc /data/jail/192.168.11.100/proc
3e4150ef 276jail /data/jail/192.168.11.100 testhostname 127.0.0.1,192.168.11.100 \\
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277 /bin/sh /etc/rc
278.Ed
279.Pp
280A few warnings will be produced, because most
281.Xr sysctl 8
282configuration variables cannot be set from within the jail, as they are
283global across all jails and the host environment.
284However, it should all
285work properly.
286You should be able to see
287.Xr inetd 8 ,
288.Xr syslogd 8 ,
289and other processes running within the jail using
290.Xr ps 1 ,
291with the
292.Ql J
293flag appearing beside jailed processes.
294You should also be able to
295.Xr telnet 1
296to the hostname or IP address of the jailed environment, and log
297in using the accounts you created previously.
298.Ss "Managing the Jail"
299Normal machine shutdown commands, such as
300.Xr halt 8 ,
301.Xr reboot 8 ,
302and
303.Xr shutdown 8 ,
304cannot be used successfully within the jail.
305To kill all processes in a
306jail, you may log into the jail and, as root, use one of the following
307commands, depending on what you want to accomplish:
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308.Bd -literal -offset indent
309kill -TERM -1
310kill -KILL -1
311.Ed
312.Pp
313This will send the
314.Dv SIGTERM
315or
316.Dv SIGKILL
317signals to all processes in the jail from within the jail.
318Depending on
319the intended use of the jail, you may also want to run
320.Pa /etc/rc.shutdown
321from within the jail.
322Currently there is no way to insert new processes
323into a jail, so you must first log into the jail before performing these
324actions.
325.Pp
326To kill processes from outside the jail, you must individually identify the
327PID of each process to be killed.
328The
329.Pa /proc/ Ns Ar pid Ns Pa /status
330file contains, as its last field, the hostname of the jail in which the
331process runs, or
332.Dq Li -
333to indicate that the process is not running within a jail.
334The
335.Xr ps 1
336command also shows a
337.Ql J
338flag for processes in a jail.
339However, the hostname for a jail may be, by
340default, modified from within the jail, so the
341.Pa /proc
342status entry is unreliable by default.
343To disable the setting of the hostname
344from within a jail, set the
345.Va jail.set_hostname_allowed
346sysctl variable in the host environment to 0, which will affect all jails.
347You can have this sysctl set on each boot using
348.Xr sysctl.conf 5 .
349Just add the following line to
350.Pa /etc/sysctl.conf :
351.Pp
352.Dl jail.set_hostname_allowed=0
353.Pp
354In a future version of
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HP
355.Dx ,
356the mechanisms for managing jails may be
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357more refined.
358.Ss "Sysctl MIB Entries"
359Certain aspects of the jail containments environment may be modified from
360the host environment using
361.Xr sysctl 8
362MIB variables.
363Currently, these variables affect all jails on the system, although in
364the future this functionality may be finer grained.
365.Bl -tag -width XXX
366.It Va jail.set_hostname_allowed
367This MIB entry determines whether or not processes within a jail are
368allowed to change their hostname via
369.Xr hostname 1
370or
371.Xr sethostname 3 .
372In the current jail implementation, the ability to set the hostname from
373within the jail can impact management tools relying on the accuracy of jail
374information in
375.Pa /proc .
376As such, this should be disabled in environments where privileged access to
377jails is given out to untrusted parties.
378.It Va jail.socket_unixiproute_only
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379The jail functionality binds IPv4 and IPv6 addresses to each jail, and limits
380access to other network addresses in the IPv4 and IPv6 space that may be available
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381in the host environment.
382However, jail is not currently able to limit access to other network
383protocol stacks that have not had jail functionality added to them.
384As such, by default, processes within jails may only access protocols
385in the following domains:
3e4150ef 386.Dv PF_LOCAL , PF_INET , PF_INET6 ,
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387and
388.Dv PF_ROUTE ,
389permitting them access to
390.Ux
391domain sockets,
3e4150ef 392IPv4 and IPv6 addresses, and routing sockets.
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393To enable access to other domains, this MIB variable may be set to
3940.
395.It Va jail.sysvipc_allowed
396This MIB entry determines whether or not processes within a jail have access
397to System V IPC primitives.
398In the current jail implementation, System V primitives share a single
399namespace across the host and jail environments, meaning that processes
400within a jail would be able to communicate with (and potentially interfere
401with) processes outside of the jail, and in other jails.
402As such, this functionality is disabled by default, but can be enabled
403by setting this MIB entry to 1.
404.El
405.Sh SEE ALSO
406.Xr newaliases 1 ,
407.Xr ps 1 ,
408.Xr chroot 2 ,
409.Xr jail 2 ,
410.Xr procfs 5 ,
411.Xr rc.conf 5 ,
412.Xr sysctl.conf 5 ,
413.Xr halt 8 ,
414.Xr inetd 8 ,
415.Xr named 8 ,
6d2362d1 416.Xr pw 8 ,
984263bc 417.Xr reboot 8 ,
3b813696 418.Xr rpcbind 8 ,
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419.Xr sendmail 8 ,
420.Xr shutdown 8 ,
421.Xr sysctl 8 ,
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422.Xr syslogd 8 ,
423.Xr tzsetup 8
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424.Sh HISTORY
425The
426.Nm
427command appeared in
428.Fx 4.0 .
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429.Pp
430Support for multiple IPs and IPv6 appeared in
431.Dx
4321.7.
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433.Sh AUTHORS
434.An -nosplit
435The jail feature was written by
436.An Poul-Henning Kamp
437for R&D Associates
438.Pa http://www.rndassociates.com/
439who contributed it to
440.Fx .
441.Pp
442.An Robert Watson
443wrote the extended documentation, found a few bugs, added
444a few new features, and cleaned up the userland jail environment.
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445.Pp
446.An Victor Balada Diaz
447wrote the support for multiple IPs and IPv6. Multiple IPs support
448is based on work done by
449.An Pawel Jakub Dawidek .
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450.Sh BUGS
451Jail currently lacks strong management functionality, such as the ability
452to deliver signals to all processes in a jail, and to allow access to
453specific jail information via
454.Xr ps 1
455as opposed to
456.Xr procfs 5 .
457Similarly, it might be a good idea to add an
458address alias flag such that daemons listening on all IPs
459.Pq Dv INADDR_ANY
460will not bind on that address, which would facilitate building a safe
461host environment such that host daemons do not impose on services offered
462from within jails.
463Currently, the simplist answer is to minimize services
464offered on the host, possibly limiting it to services offered from
465.Xr inetd 8
466which is easily configurable.