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How to configure DNS for new Firewall?

CoSmismgr asked
Last Modified: 2012-05-05
I want to switch from our Sonicwall Pro 100 firewall to a PIX 515e.

I have configured the PIX pretty straight-forward. There are two one-to-one NAT's: one for a webserver on the DMZ and one for our email server on the LAN. I have created ACL's which allow www to both the webserver and email server as well as to allow SMTP to the email server. I have tesed the PIX several times and the problem I keep having is this: SMTP packets are not getting to my email server on the LAN.

Using nslookup, set type=mx for our domain "this.is.my.domain" returns:
this.is.my.domain     MX preference = 20, mail exchanger = my.isp.domain
this.is.my.domain     MX preference = 10, mail exchanger = mail.this.is.my.domain

nslookup mail.this.is.my.domain:
Address: X.X.X.194

The IP address X.X.X.194 is addressed to the outside interface of the Sonicwall.
I am not a DNS guru and would love some expert advice on how to get this PIX working asap. I have called my ISP to schedule any needed DNS changes on their end, as they host authoritative DNS for our domain. I just don't know what to tell them!

This is an urgent matter, as the Sonicwall has been failing and will probably not last long. I am awarding maximum points for the quickest solution.

PIX config details (I will post the full config if needed):
DMZ security 50,
WAN security 0, X.X.X.194
LAN security 100,
Email server, NAT from to X.X.X.195
Webserver, NAT from to X.X.X.196
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So you added the static NATsm good, you a lso need to craft an ACL to allow the traffic in through the PIX.

access-list WAN permit tcp any host x.x.x.195 eq 80
access-list WAN permit tcp any host x.x.x.196 eq 25
ip access-group WAN in interface WAN

harbor235 :}
This one is on us!
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I have already included the ACL for port 80 and 25. I am missing something that is preventing smtp from reaching my email server.

Oh, and with the .194, if that is the case then you must change it in the static NAT as well.


Thanks pugglewuggle,

Turned out I was missing the nat statement to allow web access to LAN. All of your suggestions were correct and the PIX is online. I would like to allow access to the servers from the LAN interface when accessing by URL or public IP but will look into that now that it is functional.

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