Media for DNS Reply Modification

DNS Reply Modification

I have some ports forwarded to the outside interface on my ASA 5505. Here is an example:

static (inside,outside) tcp interface pop3 192.168.1.2 pop3 netmask

255.255.255.255

I want internal hosts to be able to connect to 191.168.1.2 by using DNS. I do not have a DNS server inside, so the hosts would have to use public DNS.

In the Cisco Security Appliance Command Line Configuration Guide I found something called DNS Reply Modification. I tried it:

static (inside,outside) x.x.x.x 192.168.1.2 netmask 255.255.255.255 dns (Where x.x.x.x is my outside ip address)

but got some sort of conflict:

WARNING: real-address conflict with existing static TCP inside:192.168.1.2/110 to outside:0.0.0.0/110 netmask

255.255.255.255

I only have one public ip address, which is why I had to use port forwarding. Perhaps that's the problem.

Is there any way to accomplish this?

Thanks