Raspberry Pi, Yaws, port forwarding and evil Squid
Last week I was trying to set up Yaws web server to serve dynamic web pages written in erlang. I thought that I succeeded because I was accessing it from my mobile device and computer. But what I forgot to notice was that I wasn't on 3G network, I was on local network. So next day I was going to work and couldnt access my webpage from the bus.
I thought it was probably a configuration issue of Yaws web server. When I got back from work I was trying all combinations to figure the problem out, but I wasn't able to solve it. I thought it might be because I made local_install from Yaws source but I wanted to be sure before reinstalling it. After that I figured out that the page was reachable from computer on my work, and also from friend's iphone. I was like omg it is probably IE problem on Lumia, but it wasn't. I found out that my mobile carrier is using Squid proxy for optimizing network traffic, so I thought it is refusing connections to my web page. So I called technical support but they didn't hear about Squid. And I was trying to figure out what else can I do, so i tried to open port 80 on router and make a port forwarding toward Yaws. And it worked.
The conclusion is that Squid proxy was for some reason blocking port 50001, and it works on port 80.
However... i wasn't connecting to my Raspberry Pi for few days now, because of New Year etc. and now it is refusing SSH, doesn't serve web page etc :(. So, I can't access it remotely, and I don't have a screen connected to it. It seems that I have to regenerate SSH keys, as answer in this question suggests. But... tomorrow.
I also bought a new charger so RPi is online 24/7.