Setting Outside IP address on Cisco ASA 5515

Nicholas Fuller · ‎12-13-2016

N00b question, but google was unable to help.

Currently I have a cable modem plugged into a netgear switch which is plugged into my cisco ASA. I am thinking I can eliminate the netgear if I configure it properly.

My 0/0 interface has a XX.XX.191.34 IP with a SubNet of 255.255.255.240

I want to add other IPs such as XX.XX.191.35 but I get a subnet error when I try to use the same subnet.

Can I just configure the 0/0 interface to use a 255.255.255.255 subnet and then on 0/2(where I want the .35 IP, to use its own 255.255.255.255 subnet?..or will it blow up? I guess I can just try and see, but I am not comfortable making those kinda changes at this point.

Karsten Iwen · ‎12-13-2016

The ASA works a little differently to a router.

You configure the interface with the address 191.34 and the corresponding subnet mask. The other addresses are not assigned to the interface but can used for NAT so that these addresses point to devices that are in your internal network.