such tunneling capabilities. This creates tun (layer 3, default) or tap (layer 2) virtual interfaces on both ends of the connection. This allows normal network management and routing to be used, and when used on routers, the traffic for an entire subnetwork can be tunneled. A pair of tap virtual interfaces function like an Ethernet cable connecting both ends of the connection and can join kernel bridges. Cyberattacks based on tunneling Over the years, tunneling and data encapsulation in general have been frequently adopted for malicious reasons, in order to maliciously communicate outside of a protected network. In this context, known tunnels involve protocols such as HTTP, SSH, DNS, MQTT. See also GPRS Tunnelling Protocol (GTP) HTTP tunnel ICMP tunnel NVGRE OSI model (Diagram) Pseudo-wire Stunnel Tunnel broker Virtual Extensible LAN (VXLAN) Virtual private network (VPN) References External links PortFusion distributed reverse / forward, local forward proxy and tunneling solution for all TCP protocols SSH VPN tunnel, see the SSH-BASED VIRTUAL PRIVATE NETWORKS section BarbaTunnel Project - Free open source implementation of HTTP-Tunnel and UDP-Tunnel on Windows VpnHood Project - Free open source implementation of a VPN using socket redirection Network protocols Computer security