Proper integration

While the XDP thing seems very reasonable, the eBPF redirections sound rather hackish. It seems to me this could be integrated into the stack natively without resorting to BPF hackery. While there are a gazillion ways of mangling and redirecting packets that are not obvious to statically analyze, a route property for loopback-routes using a secondary loopback address seem like an easy way to make this work generically.