Block access to websites available over their IP (and not a FQDN)

[Remo]

Hi community

Does anyone already managed to block access to websites available directly with their IP? Actually with regex this would be an easy task, but I have some difficulties creating a custom application signature as there isn't the full regex available and there is also the limitation that the first 7 bytes of the signature need to be a static value. So with a signature for http host header there is no chance to create a pattern for IP addresses.

Does anyone already managed to create such a signature or could point me to the right direction to create one?

Thanks,

Remo