I mentioned in my blog post that there is an SSH gateway in between. I tried this on my local system:
ssh -L 9000:127.0.0.1:8000 user@host
But when I visit http://127.0.0.1:9000/ on my local system, I get a connection reset by peer error. At the same time, in the terminal where I have set up the port forward with the ssh command above, I get this error: open failed: unknown channel type
The SSH gateway is forbidding port forwarding as well.