641 lines
20 KiB
Groff
641 lines
20 KiB
Groff
.\"
|
|
.\" Copyright (c) 2000, 2003 Robert N. M. Watson
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\"
|
|
.\" ----------------------------------------------------------------------------
|
|
.\" "THE BEER-WARE LICENSE" (Revision 42):
|
|
.\" <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
|
|
.\" can do whatever you want with this stuff. If we meet some day, and you think
|
|
.\" this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
|
|
.\" ----------------------------------------------------------------------------
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd April 5, 2007
|
|
.Dt JAIL 8
|
|
.Os
|
|
.Sh NAME
|
|
.Nm jail
|
|
.Nd "imprison process and its descendants"
|
|
.Sh SYNOPSIS
|
|
.Nm
|
|
.Op Fl i
|
|
.Op Fl J Ar jid_file
|
|
.Op Fl s Ar securelevel
|
|
.Op Fl l u Ar username | Fl U Ar username
|
|
.Ar path hostname ip-number command ...
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
utility imprisons a process and all future descendants.
|
|
.Pp
|
|
The options are as follows:
|
|
.Bl -tag -width ".Fl u Ar username"
|
|
.It Fl i
|
|
Output the jail identifier of the newly created jail.
|
|
.It Fl J Ar jid_file
|
|
Write a
|
|
.Ar jid_file
|
|
file, containing jail identifier, path, hostname, IP and
|
|
command used to start the jail.
|
|
.It Fl l
|
|
Run program in the clean environment.
|
|
The environment is discarded except for
|
|
.Ev HOME , SHELL , TERM
|
|
and
|
|
.Ev USER .
|
|
.Ev HOME
|
|
and
|
|
.Ev SHELL
|
|
are set to the target login's default values.
|
|
.Ev USER
|
|
is set to the target login.
|
|
.Ev TERM
|
|
is imported from the current environment.
|
|
The environment variables from the login class capability database for the
|
|
target login are also set.
|
|
.It Fl s Ar securelevel
|
|
Sets the
|
|
.Va kern.securelevel
|
|
sysctl variable to the specified value inside the newly created jail.
|
|
.It Fl u Ar username
|
|
The user name from host environment as whom the
|
|
.Ar command
|
|
should run.
|
|
.It Fl U Ar username
|
|
The user name from jailed environment as whom the
|
|
.Ar command
|
|
should run.
|
|
.It Ar path
|
|
Directory which is to be the root of the prison.
|
|
.It Ar hostname
|
|
Hostname of the prison.
|
|
.It Ar ip-number
|
|
IP number assigned to the prison.
|
|
.It Ar command
|
|
Pathname of the program which is to be executed.
|
|
.El
|
|
.Pp
|
|
Jails are typically set up using one of two philosophies: either to
|
|
constrain a specific application (possibly running with privilege), or
|
|
to create a
|
|
.Dq "virtual system image"
|
|
running a variety of daemons and services.
|
|
In both cases, a fairly complete file system install of
|
|
.Fx
|
|
is
|
|
required, so as to provide the necessary command line tools, daemons,
|
|
libraries, application configuration files, etc.
|
|
However, for a virtual server configuration, a fair amount of
|
|
additional work is required so as to configure the
|
|
.Dq boot
|
|
process.
|
|
This manual page documents the configuration steps necessary to support
|
|
either of these steps, although the configuration steps may be
|
|
refined based on local requirements.
|
|
.Pp
|
|
Please see the
|
|
.Xr jail 2
|
|
man page for further details.
|
|
.Sh EXAMPLES
|
|
.Ss "Setting up a Jail Directory Tree"
|
|
To set up a jail directory tree containing an entire
|
|
.Fx
|
|
distribution, the following
|
|
.Xr sh 1
|
|
command script can be used:
|
|
.Bd -literal
|
|
D=/here/is/the/jail
|
|
cd /usr/src
|
|
mkdir -p $D
|
|
make world DESTDIR=$D
|
|
make distribution DESTDIR=$D
|
|
mount -t devfs devfs $D/dev
|
|
.Ed
|
|
.Pp
|
|
NOTE: It is important that only appropriate device nodes in devfs be
|
|
exposed to a jail; access to disk devices in the jail may permit processes
|
|
in the jail to bypass the jail sandboxing by modifying files outside of
|
|
the jail.
|
|
See
|
|
.Xr devfs 8
|
|
for information on how to use devfs rules to limit access to entries
|
|
in the per-jail devfs.
|
|
A simple devfs ruleset for jails is available as ruleset #4 in
|
|
.Pa /etc/defaults/devfs.rules .
|
|
.Pp
|
|
In many cases this example would put far more in the jail than needed.
|
|
In the other extreme case a jail might contain only one file:
|
|
the executable to be run in the jail.
|
|
.Pp
|
|
We recommend experimentation and caution that it is a lot easier to
|
|
start with a
|
|
.Dq fat
|
|
jail and remove things until it stops working,
|
|
than it is to start with a
|
|
.Dq thin
|
|
jail and add things until it works.
|
|
.Ss "Setting Up a Jail"
|
|
Do what was described in
|
|
.Sx "Setting Up a Jail Directory Tree"
|
|
to build the jail directory tree.
|
|
For the sake of this example, we will
|
|
assume you built it in
|
|
.Pa /data/jail/192.0.2.100 ,
|
|
named for the jailed IP address.
|
|
Substitute below as needed with your
|
|
own directory, IP address, and hostname.
|
|
.Ss "Setting up the Host Environment"
|
|
First, you will want to set up your real system's environment to be
|
|
.Dq jail-friendly .
|
|
For consistency, we will refer to the parent box as the
|
|
.Dq "host environment" ,
|
|
and to the jailed virtual machine as the
|
|
.Dq "jail environment" .
|
|
Since jail is implemented using IP aliases, one of the first things to do
|
|
is to disable IP services on the host system that listen on all local
|
|
IP addresses for a service.
|
|
If a network service is present in the host environment that binds all
|
|
available IP addresses rather than specific IP addresses, it may service
|
|
requests sent to jail IP addresses.
|
|
This means changing
|
|
.Xr inetd 8
|
|
to only listen on the
|
|
appropriate IP address, and so forth.
|
|
Add the following to
|
|
.Pa /etc/rc.conf
|
|
in the host environment:
|
|
.Bd -literal -offset indent
|
|
sendmail_enable="NO"
|
|
inetd_flags="-wW -a 192.0.2.23"
|
|
rpcbind_enable="NO"
|
|
.Ed
|
|
.Pp
|
|
.Li 192.0.2.23
|
|
is the native IP address for the host system, in this example.
|
|
Daemons that run out of
|
|
.Xr inetd 8
|
|
can be easily set to use only the specified host IP address.
|
|
Other daemons
|
|
will need to be manually configured\(emfor some this is possible through
|
|
the
|
|
.Xr rc.conf 5
|
|
flags entries; for others it is necessary to modify per-application
|
|
configuration files, or to recompile the applications.
|
|
The following frequently deployed services must have their individual
|
|
configuration files modified to limit the application to listening
|
|
to a specific IP address:
|
|
.Pp
|
|
To configure
|
|
.Xr sshd 8 ,
|
|
it is necessary to modify
|
|
.Pa /etc/ssh/sshd_config .
|
|
.Pp
|
|
To configure
|
|
.Xr sendmail 8 ,
|
|
it is necessary to modify
|
|
.Pa /etc/mail/sendmail.cf .
|
|
.Pp
|
|
For
|
|
.Xr named 8 ,
|
|
it is necessary to modify
|
|
.Pa /etc/namedb/named.conf .
|
|
.Pp
|
|
In addition, a number of services must be recompiled in order to run
|
|
them in the host environment.
|
|
This includes most applications providing services using
|
|
.Xr rpc 3 ,
|
|
such as
|
|
.Xr rpcbind 8 ,
|
|
.Xr nfsd 8 ,
|
|
and
|
|
.Xr mountd 8 .
|
|
In general, applications for which it is not possible to specify which
|
|
IP address to bind should not be run in the host environment unless they
|
|
should also service requests sent to jail IP addresses.
|
|
Attempting to serve
|
|
NFS from the host environment may also cause confusion, and cannot be
|
|
easily reconfigured to use only specific IPs, as some NFS services are
|
|
hosted directly from the kernel.
|
|
Any third-party network software running
|
|
in the host environment should also be checked and configured so that it
|
|
does not bind all IP addresses, which would result in those services' also
|
|
appearing to be offered by the jail environments.
|
|
.Pp
|
|
Once
|
|
these daemons have been disabled or fixed in the host environment, it is
|
|
best to reboot so that all daemons are in a known state, to reduce the
|
|
potential for confusion later (such as finding that when you send mail
|
|
to a jail, and its sendmail is down, the mail is delivered to the host,
|
|
etc.).
|
|
.Ss "Configuring the Jail"
|
|
Start any jail for the first time without configuring the network
|
|
interface so that you can clean it up a little and set up accounts.
|
|
As
|
|
with any machine (virtual or not) you will need to set a root password, time
|
|
zone, etc.
|
|
Some of these steps apply only if you intend to run a full virtual server
|
|
inside the jail; others apply both for constraining a particular application
|
|
or for running a virtual server.
|
|
.Pp
|
|
Start a shell in the jail:
|
|
.Pp
|
|
.Dl "jail /data/jail/192.0.2.100 testhostname 192.0.2.100 /bin/sh"
|
|
.Pp
|
|
Assuming no errors, you will end up with a shell prompt within the jail.
|
|
You can now run
|
|
.Pa /usr/sbin/sysinstall
|
|
and do the post-install configuration to set various configuration options,
|
|
or perform these actions manually by editing
|
|
.Pa /etc/rc.conf ,
|
|
etc.
|
|
.Pp
|
|
.Bl -bullet -offset indent -compact
|
|
.It
|
|
Create an empty
|
|
.Pa /etc/fstab
|
|
to quell startup warnings about missing fstab (virtual server only)
|
|
.It
|
|
Disable the port mapper
|
|
.Pa ( /etc/rc.conf :
|
|
.Li rpcbind_enable="NO" )
|
|
(virtual server only)
|
|
.It
|
|
Configure
|
|
.Pa /etc/resolv.conf
|
|
so that name resolution within the jail will work correctly
|
|
.It
|
|
Run
|
|
.Xr newaliases 1
|
|
to quell
|
|
.Xr sendmail 8
|
|
warnings.
|
|
.It
|
|
Disable interface configuration to quell startup warnings about
|
|
.Xr ifconfig 8
|
|
.Pq Li network_interfaces=""
|
|
(virtual server only)
|
|
.It
|
|
Set a root password, probably different from the real host system
|
|
.It
|
|
Set the timezone
|
|
.It
|
|
Add accounts for users in the jail environment
|
|
.It
|
|
Install any packages the environment requires
|
|
.El
|
|
.Pp
|
|
You may also want to perform any package-specific configuration (web servers,
|
|
SSH servers, etc), patch up
|
|
.Pa /etc/syslog.conf
|
|
so it logs as you would like, etc.
|
|
If you are not using a virtual server, you may wish to modify
|
|
.Xr syslogd 8
|
|
in the host environment to listen on the syslog socket in the jail
|
|
environment; in this example, the syslog socket would be stored in
|
|
.Pa /data/jail/192.0.2.100/var/run/log .
|
|
.Pp
|
|
Exit from the shell, and the jail will be shut down.
|
|
.Ss "Starting the Jail"
|
|
You are now ready to restart the jail and bring up the environment with
|
|
all of its daemons and other programs.
|
|
If you are running a single application in the jail, substitute the
|
|
command used to start the application for
|
|
.Pa /etc/rc
|
|
in the examples below.
|
|
To start a virtual server environment,
|
|
.Pa /etc/rc
|
|
is run to launch various daemons and services.
|
|
To do this, first bring up the
|
|
virtual host interface, and then start the jail's
|
|
.Pa /etc/rc
|
|
script from within the jail.
|
|
.Pp
|
|
NOTE: If you plan to allow untrusted users to have root access inside the
|
|
jail, you may wish to consider setting the
|
|
.Va security.jail.set_hostname_allowed
|
|
sysctl variable to 0.
|
|
Please see the management discussion later in this document as to why this
|
|
may be a good idea.
|
|
If you do decide to set this variable,
|
|
it must be set before starting any jails, and once each boot.
|
|
.Bd -literal -offset indent
|
|
ifconfig ed0 inet alias 192.0.2.100/32
|
|
mount -t procfs proc /data/jail/192.0.2.100/proc
|
|
jail /data/jail/192.0.2.100 testhostname 192.0.2.100 \\
|
|
/bin/sh /etc/rc
|
|
.Ed
|
|
.Pp
|
|
A few warnings will be produced, because most
|
|
.Xr sysctl 8
|
|
configuration variables cannot be set from within the jail, as they are
|
|
global across all jails and the host environment.
|
|
However, it should all
|
|
work properly.
|
|
You should be able to see
|
|
.Xr inetd 8 ,
|
|
.Xr syslogd 8 ,
|
|
and other processes running within the jail using
|
|
.Xr ps 1 ,
|
|
with the
|
|
.Ql J
|
|
flag appearing beside jailed processes.
|
|
To see an active list of jails, use the
|
|
.Xr jls 8
|
|
utility.
|
|
You should also be able to
|
|
.Xr telnet 1
|
|
to the hostname or IP address of the jailed environment, and log
|
|
in using the accounts you created previously.
|
|
.Pp
|
|
It is possible to have jails started at boot time.
|
|
Please refer to the
|
|
.Dq jail_*
|
|
variables in
|
|
.Xr rc.conf 5
|
|
for more information.
|
|
The
|
|
.Xr rc 8
|
|
jail script provides a flexible system to start/stop jails:
|
|
.Bd -literal
|
|
/etc/rc.d/jail start
|
|
/etc/rc.d/jail stop
|
|
/etc/rc.d/jail start myjail
|
|
/etc/rc.d/jail stop myjail
|
|
.Ed
|
|
.Ss "Managing the Jail"
|
|
Normal machine shutdown commands, such as
|
|
.Xr halt 8 ,
|
|
.Xr reboot 8 ,
|
|
and
|
|
.Xr shutdown 8 ,
|
|
cannot be used successfully within the jail.
|
|
To kill all processes in a
|
|
jail, you may log into the jail and, as root, use one of the following
|
|
commands, depending on what you want to accomplish:
|
|
.Pp
|
|
.Bd -literal -offset indent
|
|
kill -TERM -1
|
|
kill -KILL -1
|
|
.Ed
|
|
.Pp
|
|
This will send the
|
|
.Dv SIGTERM
|
|
or
|
|
.Dv SIGKILL
|
|
signals to all processes in the jail from within the jail.
|
|
Depending on
|
|
the intended use of the jail, you may also want to run
|
|
.Pa /etc/rc.shutdown
|
|
from within the jail.
|
|
To kill processes from outside the jail, use the
|
|
.Xr jexec 8
|
|
utility in conjunction with the one of the
|
|
.Xr kill 1
|
|
commands above.
|
|
.Pp
|
|
The
|
|
.Pa /proc/ Ns Ar pid Ns Pa /status
|
|
file contains, as its last field, the hostname of the jail in which the
|
|
process runs, or
|
|
.Dq Li -
|
|
to indicate that the process is not running within a jail.
|
|
The
|
|
.Xr ps 1
|
|
command also shows a
|
|
.Ql J
|
|
flag for processes in a jail.
|
|
However, the hostname for a jail may be, by
|
|
default, modified from within the jail, so the
|
|
.Pa /proc
|
|
status entry is unreliable by default.
|
|
To disable the setting of the hostname
|
|
from within a jail, set the
|
|
.Va security.jail.set_hostname_allowed
|
|
sysctl variable in the host environment to 0, which will affect all jails.
|
|
You can have this sysctl set on each boot using
|
|
.Xr sysctl.conf 5 .
|
|
Just add the following line to
|
|
.Pa /etc/sysctl.conf :
|
|
.Pp
|
|
.Dl security.jail.set_hostname_allowed=0
|
|
.Pp
|
|
You can also list/kill processes based on their jail ID.
|
|
To show processes and their jail ID, use the following command:
|
|
.Pp
|
|
.Dl "ps ax -o pid,jid,args"
|
|
.Pp
|
|
To show and then kill processes in jail number 3 use the following commands:
|
|
.Bd -literal -offset indent
|
|
pgrep -lfj 3
|
|
pkill -j 3
|
|
.Ed
|
|
or:
|
|
.Pp
|
|
.Dl "killall -j 3"
|
|
.Ss "Sysctl MIB Entries"
|
|
Certain aspects of the jail containments environment may be modified from
|
|
the host environment using
|
|
.Xr sysctl 8
|
|
MIB variables.
|
|
Currently, these variables affect all jails on the system, although in
|
|
the future this functionality may be finer grained.
|
|
.Bl -tag -width XXX
|
|
.It Va security.jail.allow_raw_sockets
|
|
This MIB entry determines whether or not prison root is allowed to
|
|
create raw sockets.
|
|
Setting this MIB to 1 allows utilities like
|
|
.Xr ping 8
|
|
and
|
|
.Xr traceroute 8
|
|
to operate inside the prison.
|
|
If this MIB
|
|
is set, the source IP addresses are enforced to comply
|
|
with the IP address bound to the jail, regardless of whether or not
|
|
the
|
|
.Dv IP_HDRINCL
|
|
flag has been set on the socket.
|
|
Since raw sockets can be used to configure
|
|
and interact with various network subsystems, extra caution should be used
|
|
where privileged access to jails is given out to untrusted parties.
|
|
As such,
|
|
by default this option is disabled.
|
|
.It Va security.jail.enforce_statfs
|
|
This MIB entry determines which information processes in a jail are
|
|
able to get about mount-points.
|
|
It affects the behaviour of the following syscalls:
|
|
.Xr statfs 2 ,
|
|
.Xr fstatfs 2 ,
|
|
.Xr getfsstat 2
|
|
and
|
|
.Xr fhstatfs 2
|
|
(as well as similar compatibility syscalls).
|
|
When set to 0, all mount-points are available without any restrictions.
|
|
When set to 1, only mount-points below the jail's chroot directory are
|
|
visible.
|
|
In addition to that, the path to the jail's chroot directory is removed
|
|
from the front of their pathnames.
|
|
When set to 2 (default), above syscalls can operate only on a mount-point
|
|
where the jail's chroot directory is located.
|
|
.It Va security.jail.set_hostname_allowed
|
|
This MIB entry determines whether or not processes within a jail are
|
|
allowed to change their hostname via
|
|
.Xr hostname 1
|
|
or
|
|
.Xr sethostname 3 .
|
|
In the current jail implementation, the ability to set the hostname from
|
|
within the jail can impact management tools relying on the accuracy of jail
|
|
information in
|
|
.Pa /proc .
|
|
As such, this should be disabled in environments where privileged access to
|
|
jails is given out to untrusted parties.
|
|
.It Va security.jail.socket_unixiproute_only
|
|
The jail functionality binds an IPv4 address to each jail, and limits
|
|
access to other network addresses in the IPv4 space that may be available
|
|
in the host environment.
|
|
However, jail is not currently able to limit access to other network
|
|
protocol stacks that have not had jail functionality added to them.
|
|
As such, by default, processes within jails may only access protocols
|
|
in the following domains:
|
|
.Dv PF_LOCAL , PF_INET ,
|
|
and
|
|
.Dv PF_ROUTE ,
|
|
permitting them access to
|
|
.Ux
|
|
domain sockets,
|
|
IPv4 addresses, and routing sockets.
|
|
To enable access to other domains, this MIB variable may be set to
|
|
0.
|
|
.It Va security.jail.sysvipc_allowed
|
|
This MIB entry determines whether or not processes within a jail have access
|
|
to System V IPC primitives.
|
|
In the current jail implementation, System V primitives share a single
|
|
namespace across the host and jail environments, meaning that processes
|
|
within a jail would be able to communicate with (and potentially interfere
|
|
with) processes outside of the jail, and in other jails.
|
|
As such, this functionality is disabled by default, but can be enabled
|
|
by setting this MIB entry to 1.
|
|
.It Va security.jail.chflags_allowed
|
|
This MIB entry determines how a privileged user inside a jail will be
|
|
treated by
|
|
.Xr chflags 2 .
|
|
If zero, such users are treated as unprivileged, and are unable to set
|
|
or clear system file flags; if non-zero, such users are treated as
|
|
privileged, and may manipulate system file flags subject to the usual
|
|
constraints on
|
|
.Va kern.securelevel .
|
|
.It Va security.jail.mount_allowed
|
|
This MIB entry determines if a privileged user inside a jail will be
|
|
able to mount and unmount file system types marked as jail-friendly.
|
|
The
|
|
.Xr lsvfs 1
|
|
command can be used to find file system types available for mount from within
|
|
a jail.
|
|
This functionality is disabled by default, but can be enabled by setting this
|
|
MIB entry to 1.
|
|
.El
|
|
.Pp
|
|
The read-only sysctl variable
|
|
.Va security.jail.jailed
|
|
can be used to determine if a process is running inside a jail (value
|
|
is one) or not (value is zero).
|
|
.Pp
|
|
The
|
|
.Va security.jail.list
|
|
MIB entry is read-only and it returns an array of
|
|
.Vt "struct xprison"
|
|
defined in
|
|
.In sys/jail.h .
|
|
It is recommended to use the
|
|
.Xr jls 8
|
|
utility to see current active list of jails.
|
|
.Pp
|
|
There are currently two MIB related variables that have per-jail settings.
|
|
Changes to these variables by a jailed process do not effect the host
|
|
environment, only the jail environment.
|
|
The variables are
|
|
.Va kern.securelevel
|
|
and
|
|
.Va kern.hostname .
|
|
.Sh SEE ALSO
|
|
.Xr killall 1 ,
|
|
.Xr lsvfs 1 ,
|
|
.Xr newaliases 1 ,
|
|
.Xr pgrep 1 ,
|
|
.Xr pkill 1 ,
|
|
.Xr ps 1 ,
|
|
.Xr chroot 2 ,
|
|
.Xr jail 2 ,
|
|
.Xr jail_attach 2 ,
|
|
.Xr procfs 5 ,
|
|
.Xr rc.conf 5 ,
|
|
.Xr sysctl.conf 5 ,
|
|
.Xr devfs 8 ,
|
|
.Xr halt 8 ,
|
|
.Xr inetd 8 ,
|
|
.Xr jexec 8 ,
|
|
.Xr jls 8 ,
|
|
.Xr mount 8 ,
|
|
.Xr named 8 ,
|
|
.Xr reboot 8 ,
|
|
.Xr rpcbind 8 ,
|
|
.Xr sendmail 8 ,
|
|
.Xr shutdown 8 ,
|
|
.Xr sysctl 8 ,
|
|
.Xr syslogd 8
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
utility appeared in
|
|
.Fx 4.0 .
|
|
.Sh AUTHORS
|
|
.An -nosplit
|
|
The jail feature was written by
|
|
.An Poul-Henning Kamp
|
|
for R&D Associates
|
|
.Pa http://www.rndassociates.com/
|
|
who contributed it to
|
|
.Fx .
|
|
.Pp
|
|
.An Robert Watson
|
|
wrote the extended documentation, found a few bugs, added
|
|
a few new features, and cleaned up the userland jail environment.
|
|
.Sh BUGS
|
|
Jail currently lacks the ability to allow access to
|
|
specific jail information via
|
|
.Xr ps 1
|
|
as opposed to
|
|
.Xr procfs 5 .
|
|
Similarly, it might be a good idea to add an
|
|
address alias flag such that daemons listening on all IPs
|
|
.Pq Dv INADDR_ANY
|
|
will not bind on that address, which would facilitate building a safe
|
|
host environment such that host daemons do not impose on services offered
|
|
from within jails.
|
|
Currently, the simplest answer is to minimize services
|
|
offered on the host, possibly limiting it to services offered from
|
|
.Xr inetd 8
|
|
which is easily configurable.
|