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Checkpoint Firewall PAT/NAT not working

Posted on 2010-11-16
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2,064 Views
Last Modified: 2012-05-10
We have a CheckPoint UTM 576 TS appliance running NGX R65 build 19.
We are having a problem getting PAT and manual NAT to work.
We basically need to use a single external (public) IP to support multiple services on multiple internal servers. i.e. FTP, WEB, Email. Three different internal servers - one public IP.

Following advice from other forums, we believe that we have enabled Proxy ARP (how can we check for sure?)
We have added ARP entries for the external address with the MAC of the external interface to the local.arp file.
We have created manual NAT rules as advised by other forums and CP support (quoted below)
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" Basically you would have to create manual NAT rules.  In the Original packet side you would create a new rule at the top with an ANY as the source, the destination object in the destination column,  put what service you want to use, then in the translated packet side for the source, leave it original for the source and then put the host as the destination and leave the service as original.

Then you would have to create the reverse rule for that traffic.  Create a rule beneath that one with this info.  On the Original Packet side put the host in the source field, leave the destination filed as ANY and the same service as you had in the first rule, then on the translated packet side, put the destination in the source field, leave the destination as original and service original.

Now you would have to do the same thing for all the services you want to use for the same destination as separate rules.

Then you would have to create a rule in the regular rule base for the traffic to pass."
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Still nothing works.
Other services that are NATed  1-to-1 work fine.
We are working in a test environment during the week and test changes and new ideas live on the weekend, after hours.
Any help is appreciated.
Thanks,


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Question by:tryfwdtx
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Accepted Solution

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grimkin earned 250 total points
ID: 34153970
Hi,to test which ips you are proxy arping for, you can use "fw ctl arp".

Create a node to represent your external public IP, e.g. external_server and one to represent your internal IP, e.g. internal_server. This example is for PATing SMTP:

The NAT rules should then read:

Original Packet:
Src: ANY
Dst: external_server
Service: SMTP

Translated Packet:
Src: Original
Dst: internal_server
Service: SMTP

====================================

Original Packet:
Src: internal_server
Dst: ANY
Service: SMTP

Translated Packet:
Src: external_server
Dst: Original
Service: SMTP


HTH

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Author Comment

by:tryfwdtx
ID: 34251251
Thanks grimkin,
It took us a while to get to test in a live environment.
In addition, we also had to make manual entries into the local.arp file using the vi editor.
It is finally up and working and as of today we have it in production.
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