Today I stumbled upon a funny problem. I’m working on a piece of equipment that is a couple of hundred miles away. It sits behind a TP-Link router, model TL-MR3220 to be more precise. I access my equipment through a VPN, so I rarely have to deal with the router. Today was not one of those days.
There was a problem regarding the ISP and, long story short, I had to access the router’s web admin interface. Seems like a simple task: just start an SSH tunnel from my laptop to port 80 of the router passing through my equipment. Something like:
ssh -N -f -L 3228:192.168.15.228:80 dmelo@10.20.2.1
Then I would be able to access the admin interface on the address
http://localhost:3228. Unfortunately, after the auth, I saw almost all the
frames showing the same message “You have no authority to access this router!”.
At first, I thought it was a firmware problem. But then the problem would be even worse. How would I remotely update the firmware? I would have to do a road trip.
Looking for alternative scenarios, googling around, I found someone who had
the same problem: http://forum.tp-link.com/showthread.php?74815-You-have-no-authority-to-access-this-router!
One of the comments clarifies that the problem occurs because the router tries to
assess the referer parameter, which it expects to be on the same network as
the router.
It can be solved by modifying the referer request header. The forum suggests
using the RefControl addon for Firefox. But I only had luck using the Referer
Control extension for Chrome. After setting the referer header to the router’s
address on the local network (in my case http://192.168.15.228), it worked.