I study at a college where they use Cyberrom for Internet traffic filtering. I use Open Vpn to connect to my server run by a Webhosting company. The VPN server listens on a 40000+ port. I can connect to Open VPN form the college network. I can work on the Linux CLI without any issue. But if I use rsync or scp to transfer a file up or down, then the open vpn connection gets dropped. Then for about 15 minutes my client cannot establish a connection with the Open Vpn server. So, in order to detect what type of filtering system is used in the college firewall, I made my Open VPN server run on port 443. Then too same issue showed up. If I run a shell command on the hosting server which continuously prints out output on to the shell, then too the VPN connection gets dropped.
I tried ping flood with this command
sudo ping -i 0 -n -s 4088 somewanhost.com. The pinging starts, after some responses the pinging suddenly stops.
Web access works fine. Even I can access webpages, also I can download large files via http or https. This made me to think if only tcp is not filtered. So I used hping3 (a tcp ping tool):
sudo hping3 somewanhost.com -S -A -F -V -p 80 -i u10000. Here too the ping stops after some time. And I couldn't access web pages from the browser.
I even tried P2P clients. When I tried downloading a Linux distro on Utorrent, after enabling encryption and using a higher port, then it gives connection error. Transmission works fine, if encryption is enabled ( but it takes a long time to detect peers).
If Open Vpn works, then I can access the squid proxy installed on my webserver, and can browse without any issue.
The college does not do domain blocking or ip blocking.
I am curious to know what kind of filtering system is used. More than that, I want to get Open Vpn working, so that I can run my small website hosted on a Webhosts server.