topic Re: ASA 5505 & Multiple external IP in Network Security

ASA 5505 & Multiple external IP

frankbailey — Mon, 11 Mar 2019 18:15:47 GMT

Hi,

I have a business Broadband, which has 5 IP addresses spread over 3 class C's supernetted for it to work each IP needs to be registered to a unique MAC address.
Is there any way I can get my ASA 5505 to have all 5 ip's on one interface, listening with 5 separate MAC's

EG:
Range 80.0.0.0 - 80.0.2.254 /22

IP1 80.0.0.212 MAC 0000:0000:00A0
IP2 80.0.0.240 MAC 0000:0000:00A1

IP3 80.0.1.35 MAC 0000:0000:00A2
IP4 80.0.1.118 MAC 0000:0000:00A3
IP5 80.0.2.228 MAC 0000:0000:00A4

All on eth0 set as the external interface.

Thanks in advance

Frank

Re: ASA 5505 & Multiple external IP

David White — Sat, 24 Jul 2010 13:44:39 GMT

Hi Frank,

Unfortunately, this is not possible. All IPs that are owned by the ASA will have the same MAC. The only exception to this is for the standby IP in a failover set.

A follow-up question though. Why does each IP need to be associated with:

- a different MAC

- a specific MAC

Sincerely,

David.

Re: ASA 5505 & Multiple external IP

frankbailey — Sat, 24 Jul 2010 18:22:31 GMT

The way that my broadband works is that I get 5 IP addresses that are assigned to the cable modem, and you have to have a different MAC for each one. It would be better if they gave you a range of IP's, but they say that can't be done. So my 5 IP's are dotted about 3 subnets. I have to have a router for each one, which is a pain.
(ISP is a UK Cable Company)

Cheers

Frank

Re: ASA 5505 & Multiple external IP

David White — Sat, 24 Jul 2010 18:53:49 GMT

Hi Frank,

Unfortunately, in that case there isn't anything the ASA can do for you to help you utilize all 5 IPs.

Sincerely,

David.

Re: ASA 5505 & Multiple external IP

Nagaraja Thanthry — Sat, 24 Jul 2010 19:08:22 GMT

Hello,

If you really need to have 5 different MAC addresses, then you could

probably use a L3 switch module on a router (4 port or 9 port) and put each

port on a separate VLAN. That should allow you to register separate MAC for

each public IP and you will be able to use the firewall feature set on the

router.

http://www.cisco.com/en/US/prod/collateral/routers/ps5853/product_data_sheet

0900aecd8016bf0b_ps5855_Products_Data_Sheet.html

Hope this helps.

Regards,

Re: ASA 5505 & Multiple external IP

frankbailey — Sun, 25 Jul 2010 09:44:28 GMT

The 5 Vlan method was the first I thought of, but wasn't sure about. I will give it a whirl and report back.

Thanks

Frank

Re: ASA 5505 & Multiple external IP

frankbailey — Mon, 26 Jul 2010 07:10:27 GMT

Update:

5 Ports in 5 Vlans doesn't work.

1st interface goes in OK, but once you get to the 2nd it fires an error pointing out that they are infact on the same subnet.

Back to Square One. But thanks for the help.

Frank