📄️ How sets match traffic
The order in which b4 matches a connection to a set, how it chooses between sets, and how ASN targets are resolved.
📄️ Packet capture
How packets reach b4 with NFQUEUE and TUN, the firewall rules b4 installs, kernel requirements, and how the engine starts.
📄️ How b4 handles DNS
What b4 intercepts and how, the steps of a matched query, copied requests on KeeneticOS and older kernels, and the log lines about them.
📄️ How routing sets work
The firewall rules, marks and routing tables behind the DNS & Routing tab of a set, for integrators and for debugging.
📄️ DSCP rules
How b4 writes a set's own DSCP value, which packets carry it, why a set is refused, and the firewall rules behind it.
📄️ How Discovery searches
The phases of a Discovery run, the DNS check, alternative addresses and ECH, how the watchdog checks and heals a set, and how the DPI Detector fetches.
📄️ Which interface is which
The three interface settings of b4, what each one filters, and how to tell which one is wrong.
📄️ Packet marks
A mark is a 32-bit number the kernel keeps with a packet. Firewall rules set it and match
📄️ How TSPU works
TSPU, the Russian DPI system, and where its detailed technical description lives.