So Dan has been tweeting that there’s no good example to get started with VNET Jails with jail.conf, I thought it’s time to write one.
In this example I’ve used FreeBSD 12.1-RELEASE
root@jail-host:~ # freebsd-version
12.1-RELEASE
root@jail-host:~ # uname -a
FreeBSD jail-host 12.1-RELEASE FreeBSD 12.1-RELEASE r354233 GENERIC amd64
root@jail-host:~ #
First thing first, let’s setup a bridge on our host
root@jail-host:~ # sysrc cloned_interfaces="bridge0"
cloned_interfaces: -> bridge0
root@jail-host:~ # sysrc ifconfig_bridge0="inet 10.0.0.1 netmask 0xffffff00 descr jails-bridge"
ifconfig_bridge0: -> inet 10.0.0.1 netmask 0xffffff00 descr jails-bridge
Start the bridge0 interface without restarting the other interfaces
root@jail-host:~ # service netif start bridge0
Good! let’s setup a ZFS dataset for Jails π
root@jail-host:~ # zfs create -o mountpoint=/usr/local/jails zroot/jails
Good! now let’s fetch the base.txz file. I will be using my closest mirror, you should use yours.
root@jail-host:~ # mkdir /usr/local/jails/.dist-files
root@jail-host:~ # fetch -o /usr/local/jails/.dist-files/FreeBSD-12.1-RELEASE-base.txz http://mirror.yandex.ru/freebsd/releases/amd64/12.1-RELEASE/base.txz
Perfect!
Now, we will extract the base into the jail.
root@jail-host:~ # zfs create zroot/jails/www
root@jail-host:~ # tar xf /usr/local/jails/.dist-files/FreeBSD-12.1-RELEASE-base.txz -C /usr/local/jails/www/
Nicely done! Now let’s setup our /etc/jail.conf π
Here’s my configuration.
# vim: set syntax=sh:
exec.stop = "/bin/sh /etc/rc.shutdown";
exec.clean;
allow.raw_sockets;
allow.mount.tmpfs;
mount.devfs;
www {
$id = "10";
$ipaddr = "10.0.0.${id}";
$mask = "255.255.255.0";
$gw = "10.0.0.1";
vnet;
vnet.interface = "epair${id}b";
exec.prestart = "ifconfig epair${id} create up";
exec.prestart += "ifconfig epair${id}a up descr vnet-${name}";
exec.prestart += "ifconfig bridge0 addm epair${id}a up";
exec.start = "/sbin/ifconfig lo0 127.0.0.1 up";
exec.start += "/sbin/ifconfig epair${id}b ${ipaddr} netmask ${mask} up";
exec.start += "/sbin/route add default ${gw}";
exec.start += "/bin/sh /etc/rc";
exec.prestop = "ifconfig epair${id}b -vnet ${name}";
exec.poststop = "ifconfig bridge0 deletem epair${id}a";
exec.poststop += "ifconfig epair${id}a destroy";
host.hostname = "${name}.jail-host";
path = "/usr/local/jails/${name}";
exec.consolelog = "/var/log/jail-${name}.log";
persist;
}
Now let’s start our Jail!
root@jail-host:~ # service jail enable
jail enabled in /etc/rc.conf
root@jail-host:~ # service jail start www
Starting jails: www.
root@jail-host:~ # jls
JID IP Address Hostname Path
1 www.jail-host /usr/local/jails/www
Let’s check the networking π
root@jail-host:~ # ping -c 1 10.0.0.10
PING 10.0.0.10 (10.0.0.10): 56 data bytes
64 bytes from 10.0.0.10: icmp_seq=0 ttl=64 time=0.164 ms
--- 10.0.0.10 ping statistics ---
1 packets transmitted, 1 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.164/0.164/0.164/0.000 ms
We can do the same from the jail.
root@jail-host:~ # jexec www
root@www:/ # ping -c 1 10.0.0.1
PING 10.0.0.1 (10.0.0.1): 56 data bytes
64 bytes from 10.0.0.1: icmp_seq=0 ttl=64 time=0.087 ms
--- 10.0.0.1 ping statistics ---
1 packets transmitted, 1 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.087/0.087/0.087/0.000 ms
We can also stop all the jails.
root@jail-host:~ # service jail stop
Stopping jails: www.
Okay! Couple of notes π
You can have jail.conf at /etc/jail.conf or /etc/something.jail.conf. The problem with the latter is that if you have jail_enable="YES" in rc.conf without defining jail_list then it will run only the jails in /etc/jail.conf
There are more ways to configure VNET Jails, either with jib or jng, an example is here.
Ideally, it would be nice to have /etc/jail.d/myjail.conf, and I wrote a patch for that (D24570), if you are a FreeBSD developer, please have a look π
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