Provision of allowing only CDN's IP addresses directly on web UI

[itsKV]

The CDN / dns servers like cloudflare provide list of their server's IP address as follows. https://www.cloudflare.com/ips-v4 https://www.cloudflare.com/ips-v6

Manually entering these IPs in access list is not efficient as cf may update the IPs they use, time to time. So, providing option on web UI for auto populating the IPs from various sources at every time interval, say every 2 days will help admins to manage acls very easily.