Basic NSC routing principles

NSC implements its own DNS server, which resolves domains according to the configured routing policies.

The current sniffing-based routing flow works as follows:

The user enters a domain in their browser, for example http://reg.i2p.
The NSC FakeDNS server responds with an address from the RFC 2544 benchmarking address space (198.18.0.0/15) and stores the corresponding domain:IP mapping.
When the application attempts to connect to the assigned IP address, NSC intercepts the connection and looks up the original domain using the stored mapping.
NSC then establishes a connection to the appropriate overlay network proxy (mostly SOCKS) and forwards the intercepted traffic through it. Supported interception backends include TPROXY and eBPF.
Responses from the overlay network are forwarded back to the original application as if it were communicating directly with the resolved address.