I currently use Cloudflare for DNS only. I am interested in utilising enhanced security features such as WAF which would require me to proxy my sites (i.e. turn on the orange cloud). My issue is that I am running applications on my origin server which callback to API endpoints hosted by clients. My clients are utilising IP whitelisting and have therefore white-listed the IP address of my origin server in order for the egress traffic from my origin server to succeed. My question is this: if I enable proxy for my sites, will the IP address seen by my clients change? Or will the existing IP whitelisting rules continue to function properly?
The latter, outbound connections from your server are completely untouched by Cloudflare.