Since their introduction to stable/4 in 1999, jails have given FreeBSD lightweight containers. In 2008, the VIMAGE kernel option was introduced to stable/8 for network virtualization. In 2009, the vnet option was introduced, also in stable/8, to give jails their own network stack. Combined with the power of ZFS, vnet jails are a useful tool to add to your toolbox. In this talk we will cover: