Circumvent Censorship with Tor Bridges

ice-wzl
6 min readSep 3

Overview

Tor has become a staple over the years. It is used by journalists, activists, privacy enthusiasts and malicious cyber actors alike. Going into the intricacies of Tor is certainly beyond the scope of this post, however, today I wanted to discuss the different Tor connection methods and how they can benefit you. The genesis for this post came because, recently, my ISP has cut off my access to the Tor network. This is in the traditional sense of the word regarding both the Tor Browser and Tor via the command line (they both utilize the same sequence of events to connect). As you can see below when I attempt to connect via either means it simply hangs and never finishes the 100% connection. Trust me, I tried on many different systems and waited for multiple hours. To confirm my suspicion I even spun up a VPS with tor installed and connected with no issues.

At Home

On the VPS (Netherlands)

ISP Spying

A question I have gotten a lot is if an ISP can see Tor traffic? I would be remiss if I did not press the individual to define “see” further. The ISP can definitely identify traffic leaving a specific SOHO router device as tor traffic, however the ISP more than likely cannot see the actual content of the Tor connection. This is due to Tors many layers of encapsulation and the general routing work flow from Guard node to middle node, and finally to exit node. Thus the ISP can block certain IP addresses from connecting to known Guard nodes, which I believe is the genesis of my connection issue. Note: This connection issue has now persisted for a month with no signs of letting up.

Tor Bridges

Enter Tor Bridges. Tor bridges provide users another means of accessing the Tor network. There are three main types of tor bridges offered to end users, and we will traverse into detail with each. The first is the Obfs4 Bridge. Obfs4 is a pluggable…

ice-wzl

Reverse Engineer, Red Teamer, CTF fan & creator