New little tool: netns_tcp_bridge

Announcing my new tool: netns_tcp_bridge. It is a TCP forwarding proxy that can cross linux network namespace barriers.

Obviously, it can be done (with better performance) by using kernel itself (e.g. veth), but sometimes you may want just one temporary TCP connection in otherwise isolated namespace and do not want to deal with additional interfaces and IP addresses.

It works similar to other userland TCP forwarders, but passes all incoming accepted sockets using SCM_RIGHTS to its counterpart process.

Example invocation: netns_tcp_bridge -l 127.0.0.1:8000 -f /proc/1234/ns/net -c 127.0.0.1:8000 -t /proc/1235/ns/net