FreeBSD: Jails (2)

Here is another way to create a jail:



- Define a root directory for the jail (e.g. /usr/jails/nginx);

mkdir -p /usr/jails/nginx

- Mount the FreeBSD installation disk. In case the CD-ROM drive is used then:

mount -t cd9660 /dev/cd0 /mnt/cdrom (adjust underlined if necessary)


In case the ISO file is used and it is located in the host, then:

mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt/cdrom (adjust underlined if necessary)

- Extract the binaries from the tarballs on the install media into the declared destination. Minimally, only the base set needs to be extracted, but a complete install can be performed when preferred:

tar -xf /mnt/cdrom/usr/freebsd-dist/base.txz -C /usr/jails/nginx


Updated 27/03/2016
- Instead of mounting the ISO file, the tarballs with the binaries can be downloaded as below:

fetch ftp://ftp.freebsd.org/pub/FreeBSD/releases/amd64/amd64/10.2-RELEASE/base.txz -o /tmp/base.txz
tar -xvf /tmp/base.txz -C /usr/jails/nginx

- Copy over the host's /etc/resolv.conf to the jail:

cp /etc/resolv.conf /usr/jails/nginx/etc/

- Start the jail for basic configuration (e.g. set root password). By exiting from the shell, the jail will be shut down:

jail -c path=/usr/jails/nginx command=bin/sh


- Edit /etc/freebsd-update.conf inside jail in order to avoid errors during FreeBSD update:

from
Components src world kernel
to
Components world kernel

Reason: there are no kernel or kernel sources inside the jail.


- Edit the host's /etc/rc.conf:

#Jails
jail_enable="YES"
jail_list="lighttpd nginx" #(LIST SEPARATED BY SPACE)
ifconfig_vmx3f0_alias0="inet 192.168.0.150/24"

ifconfig_vmx3f0_alias1="inet 192.168.0.151/24"

- Create an entry for the jail on the host's /etc/jail.conf:

nginx {
  path = /usr/jails/nginx;
  mount.devfs;
  devfs_ruleset = 4;
  host.hostname = nginx1.wb.lan;
  ip4.addr = 192.168.0.151;
  allow.chflags = 1;
  exec.start = "/bin/sh /etc/rc";
  exec.stop = "/bin/sh /etc/rc.shutdown";
}

At last, restart the the host. The jail will be started automatically in the next boot.
To list the active jails use:

jls

and to access the jail e.g. JID 2:

jexec 2 /bin/tcsh


References:
- https://www.freebsd.org/doc/handbook/jails-build.html
- https://www.freebsd.org/cgi/man.cgi?jail(8)