Webfilter whitelist IP range

webfiltering is based on URL, not on I.P.   You need to whitelust the FQDNs as well, or more likely, instead of the IP address.

In the web world, host names determine behavior, so host nanes drive tbe filtering logic.

The problem is that this range is a part of Google Cloud and doesn’t resolve to a domain. The Webfilter blocks the traffic as uncategorized so it means that with a default block on there is no way to allow clients to communicate with IPs directly?

On the contrary.   Did not mean to make you despair.

If you are using an explicit IP address as your URL, that is what Web Filter will evaluate.   Many times, people want to block a DNS name using an IP address rule, and that is what does not work.

Your regex looks fine.   A partial match should also work, so you could trim it to ^https?://104\.199\.65\d+ or ^https?://104\.199\.65

Regex works, so something else is going on.   Check the logs to see if your traffic is really going through the Filter_Profile-Policy-Filter_Action sequence that has the exception.   Filter Action is not in the logs, because it is determined by policy.  

But the transparent mode destination skip list will also work, as long as Transparent Mode is what you are using.  With Standard Mode, you need to exclude the IP URLs from the proxy script, then exclude it again with the Transparent Mode Skip List.   Then the Firewall Rules can allow it to pass.

Note that if the skip list is used, the traffic is logged in the Firewall log rather than the webfilter log.

Thank you very much for your help, it seems the shorter version of the regex did the trick, now it's working flawlessly :)

Thank you very much for your help, it seems the shorter version of the regex did the trick, now it's working flawlessly :)