Hi SirDice, thanks but I did what you said:
$ ifconfig
re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 00:16:3e:85:6e:7d
inet X1.X2.X3.40 netmask 0xffffff00 broadcast...