One may use multiple systems to connect to Tor. It maybe done from different physical locations. Sometimes it is direct access to Tor, other times connection to Tor maybe via VPN. My question is how does Tor keep the entry guards persistent? What is the actual process to keep the entry guard persistent?
The guard nodes are individual per Tor process. So if you have a GNU/Linux machine and a local Tor daemon installed and also use the Tor Browser Bundle as packaged version, there are two Tor binaries on your system. Both use a different set of guard nodes and does not synchronise them in any way.
You can find the guard nodes of your Tor process by looking at the
state file. Either in your
Data/Tor directory or on
/var/lib/tor there is a file called
state. There are several lines like the following inside:
EntryGuardAddedBy 530E1038C3D2F746657B51F97831F9F422747180 0.2.4.18-rc 2013-11-11 15:04:43 EntryGuardPathBias 112.000000 112.000000 109.000000 3.000000 0.000000 4.000000 EntryGuardPathUseBias 34.000000 34.000000
Each line describes the guard node your client uses or has used. If you delete those lines your Tor process will choose a new set of guard nodes.