topic Re: Problems with traffic through a S2S VPN in Firewall and Security Management

Problems with traffic through a S2S VPN

Matlu — Thu, 15 Jun 2023 21:50:57 GMT

Hello, everyone.

I have a problem with a S2S VPN.

Currently, the traffic originating from our side, to the remote peer, is not "obeying" the security rule it has created.

The traffic is MATCHING a rule, which is almost at the end of the rulebase.

Real IP: 10.7.53.200
NAT IP: 172.26.15.151 (We don't want the remote end to know our REAL IP).
Remote End IP: 172.27.0.66

This image represents the actual rule that has been created for the VPN traffic.

This other image represents the rule with which the traffic is currently MATCHING.

This image represents the detail of a log.

Does anyone know why this is happening?
Why the traffic does not obey our security rule, if it is almost at the beginning of the rulebase?

We are testing the traffic, doing a Telnet to the destination on port 11443.

I would appreciate any comments that can help me to understand the problem.

Regards.

Re: Problems with traffic through a S2S VPN

PhoneBoy — Thu, 15 Jun 2023 22:13:52 GMT

Have you confirmed 100% the relevant traffic is actually being encrypted (going through the VPN)?
That means:

Is the source IP of this traffic (before NAT) in the local encryption domain?
Is the destination IP of this traffic (before NAT) in the remote encryption domain?
Would that traffic be routed across the VPN community stated in the rule per the configuration?

The log entry you supplied is a simple "Accept" log, which suggests the traffic isn't encrypted (and thus not matching Rule 12).

Re: Problems with traffic through a S2S VPN

Matlu — Thu, 15 Jun 2023 22:31:11 GMT

Hello,

In my VPN DOMAIN, on my side.

I have added, both the REAL IP and the NAT IP.

Currently the VPN is up in phase 1 and 2, but the traffic does not go through the rule that it really should.

Cheers

Re: Problems with traffic through a S2S VPN

Matlu — Thu, 15 Jun 2023 22:38:19 GMT

Hello,

The traffic should travel through the VPN, but as I showed in the previous images, the traffic originating from IP 10.7.53.200, to IP 172.27.0.66, "simply" does not pay attention to the explicit rule created (Rule #12).

Traffic from IP 10.7.53.200 is routed to IP 172.26.15.151.

The NAT rule is working fine.
What is not working well is the security rule.

The rule created is almost at the beginning of the rulebase, and I find it strange that the traffic does not match this rule.

Thanks for your comments.

Re: Problems with traffic through a S2S VPN

PhoneBoy — Thu, 15 Jun 2023 23:29:13 GMT

Is the 172.27.0.66 configured as part of the remote encryption domain on YOUR gateway?
Is the relevant peer gateway included in the relevant VPN Community?

When you say the NAT rule is "working" how precisely did you confirm this outside of looking at the logs?
Can you see the actual traffic with a tcpdump or fw monitor?

Unless it's solved by the above, I suspect you're going to need assistance from the TAC: https://help.checkpoint.com

Re: Problems with traffic through a S2S VPN

Matlu — Thu, 15 Jun 2023 23:51:26 GMT

A curiosity.

It is mandatory to have the Real IP, and the NAT IP, inside my "VPN DOMAIN"????

Currently I have both IPs inside my domain.

I am working with Manual NAT.

Greetings.

Re: Problems with traffic through a S2S VPN

PhoneBoy — Fri, 16 Jun 2023 00:05:16 GMT

I don't believe the NAT IP needs to be there.
However, the fact the rule is not matching suggests you have a misconfiguration with the VPN.

Re: Problems with traffic through a S2S VPN

CheckPointerXL — Sun, 18 Jun 2023 21:53:05 GMT

Are you able to try ike v1 ? Anyway an output with more than one IKE SA is not good, i would purge the tunnel

Ps please obscure sensitive data like peer ip