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Douglas Sensenig
Beginner

Multiple public IP Addresses on ASA 5505?

Hi

Is it possible to two or more public IP Addresses bound to a Cisco ASA 5505 running 8.4(2). If so, how?

Thanks in advance for your help with my request.

d

17 REPLIES 17
FlorianCokl
Beginner

Hello Douglas,

you don't need to assign multiple IP-addresses - the trick is the MASK besides that you tell ASA where to find the default gateway.

The rest is icing on a cake, and you achive this with the help of NAT.

Lets say you're provided a network with a mask of 255.255.255.248, then nets, or subnets, jump on the number 8.

  • 1. net: X.X.X.0, with 7 being the broadcast, 1 the first usable (usually the DFGW) leaving you 5 addresses
  • 2. net: X.X.X.8, with 15 being the broadcast, 9 the first usable leaving you 5 addresses
  • 3. net: X.X.X.16, with 23 being the broadcast, 17 the first usable, leaving you 5 adresses
  • and so forth

Lets take the 3rd example here, and configure the outside interface with a mask of 255.255.255.248 and the address of X.X.X.18 (the first usable besides the DFGW), or X.X.X.22 (the last usable if 17 was taken by the DFGW) - we stick with 18.

  • If you want your mail to be available through X.X.X.19 create a NAT-rule where you reference from the inside (IP of your server etc.) to the outside with the address X.X.X.19 (create a object like "WAN-ADDRESS-19" and give it the address X.X.X.19, and don't forget the ACLs!).
  • If you want your webservices to be available through X.X.X.20 create a NAT-rule where you reference from the inside (IP of your server etc.) to the outside with the address X.X.X.20 (create a object like "WAN-ADDRESS-20" and give it the address X.X.X.20, and don't forget the ACLs!).

That all works through 1 cable, 1 interface assigned with the right MASK

Hope that clears the skys?

Pls, rate right answers!

I appreciated you taking the time to answer my question.

d

Hi Douglas,

do you still need help with ASA, NAT, ACL, reachability from outside?

cheers

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