GNet Solutions » FreeBSD Administration

This is a guide on how I setup CentOS 6 in a jail on FreeBSD 10.2.

Prepare the Environment¶

• Make sure the system is up to date:
  

  pkg update && pkg upgrade
  

• Load the necessary kernel modules:
  

  kldload linux fdescfs linprocfs linsysfs tmpfs
  

• Set the linux version compatibility:
  

  echo "compat.linux.osrelease=2.6.18" >> /etc/sysctl.conf
  sysctl compat.linux.osrelease=2.6.18
  

• Install the centos linux base:
  

  pkg install linux_base-c6
  

Create the CentOS Jail¶

• Download the precreated centos filesystem:
  

  fetch http://download.openvz.org/template/precreated/centos-6-x86.tar.gz
  

• Create the centos jail directory:
  

  mkdir /usr/jails/centos6.example.com
  

• Unpack the centos filesystem into the centos6.example.com jail folder:
  

  tar xf centos-6-x86.tar.gz -C /usr/jails/centos6.example.com
  

• Mount the necessary virtual file systems into the jail’s root directory:
  

  mount -t linprocfs /usr/jails/centos6.example.com/linprocfs /usr/jails/centos6.example.com/proc
  mount -t linsysfs /usr/jails/centos6.example.com/linsysfs /usr/jails/centos6.example.com/sys  
  mount -t devfs /usr/jails/centos6.example.com/devfs /usr/jails/centos6.example.com/dev
  

• Configure the jail in /etc/jail.conf:
  

  vi /etc/jail.conf
  

  • And add the following to the end of the file:
    

    centos6 {
      path   = /usr/jails/centos6.example.com;
      mount.devfs;
      mount.fdescfs;
      mount.procfs;
      host.hostname = centos6.example.com;
      ip4.addr = 192.168.1.202;
      interface = em0;
      exec.start = "/bin/sh /etc/rc.d/rc 3";
      exec.stop = "/bin/sh /etc/rc.d/rc 0";
      mount.fstab = "/usr/jails/fstab_centos6";
    }
    

• Write some basic CentOS configuration files:
  

  cp /etc/resolv.conf /usr/jails/centos6.example.com/etc/resolv.conf
  echo "NETWORKING=yes" >> etc/sysconfig/network
  echo "linproc /usr/jails/centos6.example.com/proc linprocfs rw 0 0" >> /usr/jails/fstab_centos6
  echo "192.168.6.6 localhost localhost.localdomain localhost4 localhost4.localdomain4 centos6 centos6.example.com" >> /usr/jails/centos6.example.com/etc/hosts
  

• Create the password database for the jail:
  

  cd /usr/jails/centos6.example.com/etc 
  echo "root::0:0::0:0:Charlie &:/root:/bin/bash" > master.passwd
  pwd_mkdb -d ./ -p master.passwd
  

• Chroot into the centos6.examepl.com jail directory:
  

  chroot /usr/jails/centos6.example.com /bin/bash
  

  • And prepare the environment:
    

    cd /etc
    pwconv
    grpconv
    passwd
    touch /etc/fstab
    touch /etc/mtab
    cd /sbin
    mv consoletype consoletype.orig
    ln -s /bin/true consoletype
    cd /bin
    mv umount umount.prev
    ln -s /bin/true umount
    chkconfig httpd off
    chkconfig ip6tables off
    exit 
    

• Enable jails to start at boot:
  

  echo 'jail_enable="YES"' >> /etc/rc.conf
  

• And start the jail
  

  service jail start centos6.example.com
  

• Check that the jail is running:
  

  jls
  

Resources¶

• https://bluehatrecord.wordpress.com/2015/09/19/the-midnight-oil-jailing-centos6-in-freebsd-10-2/
• https://www.freebsd.org/doc/handbook/linuxemu-lbc-install.html