隧道协议（英语：Tunneling Protocol）是一种网络协议，在其中，使用一种网络协议（发送协议），将另一个不同的网络协议，封装在负载部份。使用隧道的原因是在不兼容的网络上传输数据，或在不安全网络上提供一个安全路径。

隧道则是对比分层式的模型，如OSI模型或TCP/IP。隧道协议通常（但并非总是）在一个比负载协议还高的层级，或同一层。要了解协议堆叠，负载和发送协议都须了解。传统的分层式协议，如OSI模型或TCP/IP模型，HTTP协议 ，并不被认为是穿隧协议。

Generic Routing Encapsulation是一种跑在 IP （IP 号码为 47）的协议，身为网络层上的网络层的例子，通常是用带有公开地址的 IP 封包来携带带有 RFC 1918 私用地址的 IP 封包来穿越互联网。在此例上，发送和负载协议是兼容的，但负载地址和发送网络是不兼容的。

In computer networks, a tunneling protocol allows a network user to access or provide a network service that the underlying network does not support or provide directly. One important use of a tunneling protocol is to allow a foreign protocol to run over a network that does not support that particular protocol; for example, running IPv6 over IPv4. Another important use is to provide services that are impractical or unsafe to be offered using only the underlying network services; for example, providing a corporate network address to a remote user whose physical network address is not part of the corporate network. Because tunneling involves repackaging the traffic data into a different form, perhaps with encryption as standard, a third use is to hide the nature of the traffic that is run through the tunnels.