Tor bridges and how they avoid censorship

Question

Censorship to the tor network is an option as the ISPs can detect an attempt of connection to one of the known tor nodes, as these are public. But if I as a user of the tor network can gain access to the ip addresses of the bridges how comes that the ISPs \ companies who makes the censorship cant? As i understand it, when using a bridge the packets should go through an additional station which is the bridge, which makes the bridge the "entry node", which means that my ISPs can see that i try to talk to an ip address which is a bridge and block me the same way they do with the normal tor relays.

So how does the bridges keep themselves undetected from censorship?

Answer 1

You have a point that you can gain access to it addresses of tor bridges. But not easily

You will notice there is no publicly available list of all bridges. You can only request 3 at a time from the Tor project site

The primary defense against discovery is through obscurity: simply it is not worth the effort to try to find the potential thousands of bridges three at a time

And some bridges are blocked. Trust me, I was in highschool once :-).

Answer 2

As i understand it, when using a bridge the packets should go through an additional station which is the bridge, which makes the bridge the "entry node", which means that my ISPs can see that i try to talk to an ip address which is a bridge and block me the same way they do with the normal tor relays.

They can. But it is much harder to block bridges than public relays since you need to do a whole lot of DPI things to know whether a bridge relay is hosted on the IP address.

To avoid such blocking, use Pluggable Transports. Their purpose is to hide the presence of a bridge, and some have active probing resistance against such attacks.