We had a user who needed to access a site which wasn’t hosted on port 80 and which also wasn’t accessible on port 443.
The site was given out like this – http://www.mydomain.com:8443. This was common some years ago before the availability of http1.1 and it’s support for virtual hosts. Now…not so much.
The problem with this is that we use a Smoothwall here because it has a solid name in the education sector, and it’s proxy setup is solid, but it can be a bit of a brutal beast when it comes to it’s interface and how to make changes so it took me a bit of hunting to work out how to allow this setup.