topic access to azure web server via office CP and s2s VPN in Firewall and Security Management

access to azure web server via office CP and s2s VPN

Mark_Edwards — Wed, 12 Feb 2025 09:02:11 GMT

Hi,

customer has a S2S VPN from the office Check Point to Azure.

They are able access all their servers hosted in Azure via the VPN.

Now they want to access an Azure web server from the Internet but via the office CP.

I have implemented the following:

1. Added a rule allowing Internet access to the web server public IP (https)

2. Added a source and destination NAT rule

where

original source - Internet

original destination - 196.x.x.x

translated source - 172.30.x.x (internal IP)

translated destination - 192.168.x.x

3. Added the public IP to the Azure VPN domain

4. Internal IP included the CP gateway VPN domain

5. Changed VPN routing to "To center or through the center to other satellites, to Internet and other VPN targets"

Logs show the traffic being "Encrypted in the community" and the relevant NAT rule applied.

However we can't access the web site.

tcpdump and fw monitor do not capture anything for the translated source or translated destination IPs.

I suspect that the traffic does not traverse the VPN, maybe because not being translated?

fw monitor does show this for my IP, from what I understand the NAT should have taken place before the "Post-Outbound VM"

[vs_0][ppak_0] eth1:Oe[44]: 41.160.x.x -> 196.x.x.x (TCP) len=52 id=51573
TCP: 56844 -> 80 .S.... seq=106564e8 ack=0000000

Am I missing any configs?

Re: access to azure web server via office CP and s2s VPN

PhoneBoy — Fri, 14 Feb 2025 21:55:15 GMT

Why route traffic for a cloud-hosted resource through an on-premise gateway?

Only traffic that originates from the encryption domain BEFORE NAT will be encrypted.
The only way I could see this working is with a route-based VPN where your local encryption domain is NULL.
If you're using a Domain-Based VPN, this is not likely to ever work.

Re: access to azure web server via office CP and s2s VPN

Mark_Edwards — Fri, 21 Feb 2025 11:10:08 GMT

Hi,

They don't have any security in Azure apart from security groups.

We managed to get it working by adding the on-premise public IP to the Azure encryption domain, unchecking disable NAT in the VPN community and adding manual NAT rules.