ASA with Pubilc IP's on both sides

Unanswered Question
Jul 1st, 2010

HI All,

I have a ASA which i would like to put between my router and server but im stuggling to fine a sample config,

The router fully supports all our public ip's directly through and the individual servers which have the public address manually configured, I want to place the asa between the two point and just setup access list to allow specific traffic. Does any one have any ideas on how i can achieve this.


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Federico Coto F... Thu, 07/01/2010 - 05:59


If the ASA is going to have public IPs on the outside and inside, then you can avoid NAT on the ASA.

All you need to take into account is that outbound traffic is permitted by default and inbound traffic must be explicitly permitted by an ACL.

I assume that the ASA is going to act as a Firewall so configure the appropiate Firewall rules as well.


abolton291078 Thu, 07/01/2010 - 06:39

would this use two public ip through, i do remember in the past i have used ip unnumbered but the asa doesent seem to support this,

Federico Coto F... Thu, 07/01/2010 - 06:42

The ASA does not support unnumbered interfaces or loopbacks, what I'm saying is that you can have public range of IPs on both outside and inside.

In that case, NAT is not necessary on ASA.


Federico Coto F... Thu, 07/01/2010 - 07:03

I agree with Michael's suggestion.

Just remember the limitations associated with having the ASA in transparent mode (no VPN support, no dynamic routing protocols, etc).



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