It’s actually called SO_REUSEPORT Kernel 3.9 introduced a new cool feature in SOCKET interface called SO_REUSEPORT. So what is it? As the official documentation says, it allows multiple AF_INET or AF_INET6 sockets to be bound to an identical socket address. before binding a socket to an interface, each one should have this option enabled. This way, mutiple processes can listen on the same port at the same time! How Can This Possibly Be Secure?