Log X-Forwarded-For for rpc #9397

Our recommend config for remote use of RPC advise people to use stunnel. One consequence of this is the logs lose all information about where the connection came from. I believe stunnel sets x-forwarded-for (but haven't verified), if so we should log this information.

Slight NACK.

• I remember fun adventures with X-forwarded-for "IP spoofing" more than 10 years ago. This information can be inserted by anyone and set to anything, it should not be taken seriously.
• I'm fairly sure stunnel doesn't set X-forwarded-for at all, see the TODO: https://www.stunnel.org/sdf_todo.html
• Also stunnel is usually set up as a protocol-neutral tunnel, so it won't do anything in the sense of HTTP header manipulation

I'd say the proper way to do logging w/ multiple tunnels is one of, or both:

• Bind RPC on multple ports, give each tunnel its own destination address/port, log that
• Use the RPC multi-account feature and give every tunnel user their own account.

My suggestion would be to log the x-forwarded-for as additional information, like xff: <foo>. Not to replace the IP address. Just preserve additional information. But on the todo and protocol neutrality you've got me there.

This feature suggestion was tendered on the basis of encountering someone who had their stunnel rpc port open to the internet and they were being DOS attacked via it, and had no idea it wasn't their own hosts... it was pre-auth.

I think this issue can be closed as wont-fix. However, I think the only docs we have regarding stunnel are in the 0.12 release notes and were not sufficient for me trying to follow them (we could mention the stunnel conf file, firewall rules, etc -- not to mention @laanwj suggestions in the above comment).

Closing for now due to lack of progress and direction. Pull requests with improvements are welcome, and it is possible to re-open this issue or create a new one if this feature is requested again.