Most clients supports what we call Forward Proxying: You explicitly tell it which server (and port) to use as a proxy. This has traditionally been done over HTTP, with the addition of support for the CONNECT method for HTTPS request. We are now starting to see some clients supporting Forward Proxy over HTTPS, and you might wonder why? Well, a few reasons could include
- Even with CONNECT there can be some leakage of information. The CONNECT request includes the destination server and port, in clear text.
- Authentication to the proxy.
- Overal, we're transitioning away from HTTP.
I saw this tweet from Daniel Stenberg, looking for volunteers to implement support for this in curl. I don't know if he's got any takers yet :). Firefox and Chrome both are working on this feature, Chrome already having the basics available. Since I work on a proxy server (Apache Traffic Server), I took the opportunity to test it with the latest Chrome. Lo and behold, it simply worked right out of the box! I started chrome with this (OSX) command:
% Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --proxy-server=https://localhost:443