Is it common for HTTP proxy to connect to ANY destination port indicated in HTTP request? Or usually set of destination ports is restricted (80, 8080, 443, ...) I created WCF service and Visual Studio assigned address http://localhost:7517/ But some customers can use web proxies and it seems that using standard 80 or 8080 is good idea for WCF service, doesn't it? Otherwise what is the benefit HTTP based WCF VS TCP based WCF... From other side 80 or 8080 can be occupied already. What are the most common proxy destination port restrictions nowadays? This information is useful for setting WCF HTTP transport based service port.
SnapOverflow
Yes, this is very often restricted. Particularly any proxy based on squid, as this functionality is standard. Also it is a line of defence against people tunneling through proxies.
Squid standard config has
Many people knock off the high ports, too.
My advice is to try and stick to 80 and 443 where possible for Web services, outside that it can be hard to predict which proxies will block. If you are serving a market such as education where filters or proxies are almost ubiquitous, it's definitely worth playing safe.