func Run(sm *subnet.SubnetManager, tepIface *net.Interface, tepIP net.IP, port int, ipMasq bool, ready backend.ReadyFunc) { sn, err := acquireLease(sm, tepIP) if err != nil { log.Error("Failed to acquire lease: ", err) return } tun, tunName, err := ip.OpenTun("rudder%d") if err != nil { log.Error("Failed to open TUN device: ", err) return } localAddr := net.UDPAddr{ Port: port, } conn, err := net.ListenUDP("udp4", &localAddr) if err != nil { log.Error("Failed to start listening on UDP socket: ", err) return } // Interface's subnet is that of the whole overlay network (e.g. /16) // and not that of the individual host (e.g. /24) tunNet := ip.IP4Net{ IP: sn.IP, PrefixLen: sm.GetConfig().Network.PrefixLen, } // TUN MTU will be smaller b/c of encap (IP+UDP hdrs) var mtu int if tepIface.MTU > 0 { mtu = tepIface.MTU - encapOverhead } else { log.Errorf("Failed to determine MTU for %s interface", tepIP) return } err = configureIface(tunName, tunNet, mtu) if err != nil { return } if ipMasq { err = setupIpMasq(tunNet.Network(), tunName) if err != nil { return } } // all initialized and ready for business log.Info("UDP encapsulation initialized") ready(sn, mtu) fastProxy(sm, tun, conn, tunNet.IP, uint(mtu), port) }