TUN traffic is sent ad-verbatim between the two endpoints via unencrypted UDP packets. Thus, this should only be used if a more secure protocol (like SSH; see github.com/dsnet/sshtunnel) is running on top of this VPN. In order to prevent attackers from connecting to other locally binded sockets on the endpoints, a simple port filter is built-in to restrict IP traffic to only the specified ports. Users of udptunnel should also setup iptable rules as a secondary measure to restrict malicious traffic. This only supports Linux.