Echo Protocol
| Internet protocol suite |
|---|
| Application layer |
| Transport layer |
| Internet layer |
| Link layer |
The Echo Protocol is a service in the Internet Protocol Suite defined in RFC 862. It was originally proposed for testing and measurement of round-trip times in IP networks.
A host may connect to a server that supports the Echo Protocol using the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP) on the well-known port number 7. The server sends back an identical copy of the data it received.
The functionality of the Echo Protocol was superseded by the echo request of the Internet Control Message Protocol and the corresponding ping utility.
Inetd implementation
On UNIX-like operating systems an echo server is built into the inetd daemon. The echo service is usually not enabled by default. It may be enabled by adding the following lines to the file /etc/inetd.conf and telling inetd to reload its configuration:
echo stream tcp nowait root internal echo dgram udp wait root internal