Issue with NAT over Site-2-Site VPN

L1 Bithead

Issue with NAT over Site-2-Site VPN

Hi there,

 

I am reasonably good with Palo Alto Firewall however struggling with the NAT over VPN. I am trying to hide some internal IPs behind 9.9.0.1/32 and 9.9.0.1/32 is configured in Proxy ID as Local host. VPN phase 3 comes up but i think the way i am doing NAT is wrong.

 

NAT policy is created is as follows

 

Source Zone             Destination Zone           Sourec Address           Destination Address                 Destination Translation

       VPN                       T rust                                10.1.0.1                            9.9.0.1                             Internal Host 10.129.34.9

 

When i check on CLI it tells me that request for 9.9.0.1 will be translated to 10.129.34.9

 

PA-1(active)> test nat-policy-match source 10.1.0.1 destination 9.9.0.1 protocol 70

 

Destination-NAT: Rule matched: Total_VPN_NAT-1
9.9.0.1:0 => 10.129.34.9:0

 

I dont see request coming when i monitor the traffic. However when i packet capture i do see ping request coming but it dies off becuase of no return response.

 

Can someone help or suggest what could be wrong please?

 

Many Thanks

L5 Sessionator

Re: Issue with NAT over Site-2-Site VPN

Ping comes through and is translated correctly? In that case check the routing for response maybe?

L1 Bithead

Re: Issue with NAT over Site-2-Site VPN

No i wudn't say ping comes thru because i dont see anything in monitor tab however when i capture the packet using packet capture tool i do see ping coming but my firewall isn't responding. 

 

Routing is not a problem because other Proxy IDs are working fine. It only this specific IP which i am trying to NAT is having problem. 

Capture1.JPG

L5 Sessionator

Re: Issue with NAT over Site-2-Site VPN

This packet isn't translated, it has original destination 9.9.0.1. Seems your NAT isn't working.

 

 

L1 Bithead

Re: Issue with NAT over Site-2-Site VPN

Thats what i think as well however when i check the CLI is does say 9.9.0.1 will be translated to 10.129.34.9.

 

PA-1(active)> test nat-policy-match source 10.1.0.1 destination 9.9.0.1 protocol 70

 

Destination-NAT: Rule matched: Total_VPN_NAT-1
9.9.0.1:0 => 10.129.34.9:0

 

 

Capture2.JPG

 

Is there any way to check why my NAT rule isnt working please?

L5 Sessionator

Re: Issue with NAT over Site-2-Site VPN

Is 9.9.0.1 in trust zone? If it isn't, NAT won't hit.

L4 Transporter

Re: Issue with NAT over Site-2-Site VPN

Hi nvirmani,

 

When you run a test nat policy command, try putting in the 'to' & 'from' fields to include the zones, as your NAT rule is done with zones. Personally I always make the test commands as accurate as possible for the best results.

 

Ben

L1 Bithead

Re: Issue with NAT over Site-2-Site VPN

Hello

 

I'm having a very similar issue with trying to configure a NAT translation from VPN to Trusted zone. In my case I'm building a VPN tunnel for monitoring using /32 ProxyIDs. My configuration VPN ProxyID is like the example below:

 

Remote:                       Local:

3.3.3.3/32                   172.25.40.3/32

 

My NAT is configured as follows.

Source Zone:                  Dest Zone:                  Source Address:         Dest Address:                Destination Trans:

VPN                                Trusted                         3.3.3.3/32                  172.25.40.3/32              10.100.10.10/32

 

I can't get the translation to happen when send pings from the VPN and that's what I need working.

 

If I switch from a Dest translation to Source translation it works when I ping from Trust to VPN.

Source Zone:            Dest Zone:                   Source Address:            Dest Address:             Source Trans:

Trusted                      VPN                              10.100.10.10/32          3.3.3.3/32                   172.25.40.3/32

 

What am I missing? Do I need to add a static route for the V-Router? To get to 172.25.40.0/32 use tunnl.x?

 

Please advise. Thanks.

 

Ben

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