FreeBSD - IPFW nat - ядерный nat

Ядро

include         GENERIC
options         IPFIREWALL
options         IPFIREWALL_VERBOSE
options         IPFIREWALL_VERBOSE_LIMIT=4000
options         IPFIREWALL_DEFAULT_TO_ACCEPT
options         IPFIREWALL_FORWARD
options         DUMMYNET
options         IPDIVERT
## IPFW_NAT
options         IPFIREWALL_NAT
options         LIBALIAS
options         ROUTETABLES=2
options         HZ="1000"

Можно включить без пересборки

/etc/tc.conf:
firewall_nat_enable="YES"
dummynet_enable="YES"