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New Member

External DNS not directing back in internally

I'm stumped on this one. Our ISP handles our DNS services and last week I added a host name with them that points to a

static public IP on our network, I'll call it: 209.209.209.209

This hostname/address is for a private webserver I'm running internally and I need to be able to access it using the host name externally and internally but so far it only seems that the host name works on the outside. I can't seem to figure out what I'm doing wrong or forgetting to do to allow internal users to also access it with the hostname. I configured my PIX over a year ago and I've forgotten a lot of what's required.

I've added the following two lines to my PIX 515e with no success.

access-list 100 permit tcp any host 209.209.209.209 eq www

static (inside,outside) 209.209.209.209 192.168.10.4 netmask 255.255.255.255 0 0

Do I need to route DNS somehow specifically for this IP or is it something that is done automatically?

Thank for any direction that can be provided.

Chris

5 REPLIES
New Member

Re: External DNS not directing back in internally

Hi Chris,

This is always an issue when you use an external DNS server to resolve internal hosts.

There are two solutions.

PIX OS 6.2 and higher:

static (inside,outside) 209.209.209.209 192.168.10.4 netmask 255.255.255.255 dns

PIX OS 6.1 and before:

alias (inside) 192.168.10.4 209.209.209.209 netmask 255.255.255.255

Both solutions translate the DNS A record for the internal host.

Regards,

Dave

New Member

Re: External DNS not directing back in internally

Thanks for your response Dave. The PIX OS is 6.3.

I actually tried the first solution already with no success. As I stated in my initial post in this thread I have tried:

static (inside,outside) 209.209.209.209 192.168.10.4 dns netmask 255.255.255.255 0 0

I accidently omitted the 'dns' from my post since I was typing from memory but it was in the config. Isn't that the same as your first solution.

New Member

Re: External DNS not directing back in internally

So I'm at a loss why this is not working...

I've confirmed that my host name "webtimesheets.mydomain.com" refers to:

209.209.209.209

I've confirmed that I can reach the webserver that the host name refers to externally from the internet using either the host name "webtimesheets.mydomain.com" or the IP:

209.209.209.209

I've confirmed that this line is in my config:

static (inside,outside) 209.209.209.209 192.168.10.4 dns netmask 255.255.255.255 0 0

I've confirmed that I can reach my server internally using the IP:

192.168.10.4

But I can not reach the server internally using the hostname "webtimesheets.mydomain.com"!

Please if some one has any ideas I would appreciate them. Thanks.

Chris

New Member

Re: External DNS not directing back in internally

I think I figured out what the problems was...

I had the following line in my config in a spot where I wasn't looking:

http 209.209.209.209 255.255.255.255 inside

I'm guessing this is to use PDM(?) over http which I believe we used last year to configure the PIX initially. This IP had previously been used by a Dell laptop I had been using to configure the PIX and it used that IP.

Maybe that wasn't the problem but it is working now.

New Member

Re: External DNS not directing back in internally

Hi,

Alternatively, you could try:

alias (inside) 192.168.10.4 209.209.209.209 netmask 255.255.255.255

Alias was used prior to 6.2. It should also re-write the DNS A-Record.

Regards,

Dave

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