ASA 5510 Guest Internet Access

Question

I have a subnet for guest network access, both wired and wireless.  We have a Netgear ProSafe that is trunked to a Cisco 2901 performing 'Router-on-a-Stick'.  For most internal traffic, it all stays behind the ASA.  But for guest traffic, I have a route-map that sets the next-hop address as the outside interface of the ASA.  The question is, how can I still permit those users to access our internal DNS servers?  Do I need any particular NAT translations, exemptions, DNS doctoring, hairpinning, etc.?  I have an ACL on the inside interface that permits traffic from the guest networks to our internal DNS servers, and then the next ACL line denies any other traffic from the guest networks to any of our internal networks.
Regards,
Scott

Answer 1

Hello Scott,
Your ASA will need to have a route for both networks
You also will need the following command:
          -same-security-traffic permit intra-interface
The thing is that the packets from the guest vlan will go directly to the ASA as its default gateway, then packets will be routed to the Router on stick and finally to the DNS server, the reply will go from the DNS to the Router on stick and then directly to the Guest user.
Nat exemption will look like this:
access-list nonat permit ip 192.168.14.0 255.255.255.0  host 192.168.11.6
access-list nonat permit ip 192.168.14.0 255.255.255.0  host 192.168.11.4
nat (inside) 0 access-list nonat
Please give it a try, also please provide packet tracer
packet-tracer input inside udp 192.168.14.10 1025 192.168.11.4 53
Regards,
Julio
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