Secondary IP On Cisco ASA
While decommissioning some old routers, I need to transfer an IP address to an ASA on a subnet. Unfortunately the ASA’s don’t allow you to do this. The standard “ip address X.X.X.X Y.Y.Y.Y secondary” doesn’t work.
I did a quick google and this beautiful bastard had the solution, static ARP with proxy-arp.
Figure out what the existing MAC is on the interface by issuing;
Then use that mac address along with proxy ARP for your secondary IP:
arp DMZ 192.168.3.3 0000.1111.2222 alias