I have a closed-source VPN program that messes up my system (Fedora Linux): I run it, it changes something, VPN works, but when I terminate the connection, my system is left in a dirty state and the networking is broken (DNS in particular, even though
/etc/resolv.conf is restored correctly).
I would like to keep track of what changes are made by that program (which is a Java program with GUI, if I am not mistaken) on my system. This should include at least file system and networking configuration.
I thought about using strace, but the output is probably too messy and low-level to let me understand what is happening. Also I found fssb which could be nice at fs level, but I still need to understand what's going on the network configuration and I don't know what tool to use.
What tools I can use?