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PIX NAT Problem

I setup a PIX with three interfaces, OUTSIDE-INSIDE-DMZ. From the internet I can browse the webserver's (sitting on the DMZ) public NAT IP address but from inside I cannot connect to the public IP.

Is there any workaround on this issue? Need your help badly...

Thanks,

Ivan

  • Other Security Subjects
5 REPLIES
Cisco Employee

Re: PIX NAT Problem

Hi Ivan,

Use the 'alias' command to resolve the issue. This url will be helpful.

http://www.cisco.com/en/US/partner/products/hw/vpndevc/ps2030/products_tech_note09186a0080094aee.shtml

Thanks,

yatin

Cisco Employee

Re: PIX NAT Problem

Hi Ivan,

So you will need to do Destination NAT, as the example in the url;

alias(inside) 99.99.99.99 192.168.100.10 255.255.255.255

where 99.99.99.99 is public addr for the web server and 192.168.100.10 is its DMZ address.

Hope this helps.

yatin

Re: PIX NAT Problem

Hi yatin

Thanks for the help, when I tried the alias command on the inside interface I manage to ping the public NAT ip from internal but the thing is I still cannnot browse the website from internal. I browse the website from internal via its URL www.website.com(internal DNS resolve this as public IP) and it shows me "page cannot be displayed error", but if browsing it's private ip it works.

DO you have any advise what points I forgot to check.

Thanks Again, :)

Ivan

Silver

Re: PIX NAT Problem

Hello Ivan,

Thanks for your question. What you are trying to do is called destination NAT. In that case you can configure alias or the bi-directional NAT.

alias (inside) public_ip dmz_ip

Also, you may want to turn off proxy arp on the inside interface of the pix. I hope this helps.

Regards,

Mynul

Re: PIX NAT Problem

Hi Mynul,

Our network setup is like this: our Public DNS server is inside the DMZ zone, this DNS server also acts as a proxy server for internal(inside) users. The web servers are also sitting inside the DMZ zone. Even the DNS Server cannot browse the webserver URL.

I noticed that all cisco docs on alias follow the setup whereby the DNS is sitting outside the PIX.

thanks,

Ivan

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