Kernel Support Table

Kernel	IPv4	IPv6	IPv4 NAT	IPv6 NAT	Needs kmem	Needs root
DragonFly BSD	Yes	Yes	No	No	No	Yes
FreeBSD 5+	Yes	Yes	No	No	No	Yes
Linux	Yes	Yes	Yes	Yes	No	No
NetBSD 5+	Yes	Yes	No	No	No	Yes
OpenBSD 3+	Yes	Yes	Yes	No	No	No