Tor Blocked: How to Know Its Origin?

Question

I do have access to the Tor network from a university in Europe. In order to be able to connect internet, we must first configure the connection with a proxy (the university is the the ISP), so have to provide for IPv4 an Address, a Netmask, a Gateway, a DNS. There was no data provided for IPv6, but when “Details” are checked, there is one (I suppose it came automatically). Every works fine with that connection for ordinary (non Tor based) internet browsing.

In the past (few years ago), I was still using Windows 7 and did run several the TBB, connected directly to Tor, but for reasons of discretion, the obfs4 bridges were used most of the time. Some 2 years ago, Windows was abandoned for Linux (still in use), more precisely currently using the latest version of Linux Mint (Cinnamon, 64 bit).

The problem is the following: when trying to connect directly to the Tor network, the browser will not be able to make a connection (it keeps on trying to establish a connection, then fails). In the past, with older version of this Linux distro (17.2, 17.3), similar problems encountered, although it could be solved with the use of bridges, at least obfs4, obfs3 and meek. Now the problem is that even obfs4 and obfs3 do not work, only meek (but is pretty slow), so bridges have to be requested (not a problem with the latest version of the TBB, great stuff by the way !) and it works fine. Yet, it would be still better if obfs4 could be used (= more users).

The big issue is that I am not even sure that the problem comes from the ISP trying to block the access to Tor or simply from something wrong on my side (a port problem or whatever). As said above, the university is in Europe (not in a country run by a dictator) and I don’t think they would have a reason to block Tor (they just use simple key words based filtering system to prevent students to surf on clearnet porn sites and the like, but using a VPN is not a problem to circumvent the filter for instance), so I get the feeling that the problem is rather on my side but I have no idea how to find out. Is there a script, a command line, a test, an application that could be determine the origin of the problem, and eventually finding out if the issue is from them or from my settings.

Thanks for reading and possibly providing guidance or testings.

Answer 1

You can use OONI Probe to run a batch of censorship tests. Generally, if you can use a VPN, there is almost no chance that your local configuration is problematic. Most of the time it is TBB's built-in bridges that are blocked.