While there are many intercepting proxy servers in use today, it is possible to detect them using various methods. You can detect the presence of intercepting proxy servers by comparing a client’s external address to an address seen through the external web server. It is also possible to detect these proxies by examining HTTP headers that are received by the scrapebox proxy server. There are hundreds of websites that are created for the purposes of detecting intercepting proxy servers. They do this by reporting a client’s IP address, which is seen through the website back to the client in a given webpage.
Secondly, you can detect the presence of an intercepting proxy by comparing results of various internet IP checkers when they are accessed using either HTTP or HTTPS. This is possible because an intercepting proxy does not have the capacity of intercepting SSL. Where there is hunch of SSL interception, a user can be able to examine all certificates associated with the secure website. In this case, root certificates must indicate whether they were issued for reasons of intercepting. When using an ssl proxy to access a website, you will be able to know the presence of an intercepting proxy by comparing sequences of network hops.
You can also detect an intercepting proxy by trying to make connections to IP addresses known to have no servers. The private proxies will accept your connections and then try to proxy on the connections. When it is determined that there are no servers that can accept the connections, the proxies will return error messages or close your connections. It is actually easy to detect this difference in behavior. For example, many web browsers generate error pages created by a browser in case connection to HTTP servers is impossible but still return an error message in case a connection goes through at which point the connection will be closed.