The ECHO service is an internet protocol defined in RFC 862. It was originally proposed as a way to test and measure an IP network. Now, testing and measurement is more commonly done with ping and traceroute.

A host may connect to a server that supports the ECHO protocol on either TCP or UDP port 7. The server then sends back any data it receives, with no modification by the echo server.

Linux

In Linux, an echo server is built into the inetd daemon. To enable the echo service, edit the /etc/inetd.conf file, then send inetd a SIGHUP signal. This causes inetd to re-read the /etc/inetd.conf file.

On Linux, you can send inetd the SIGHUP signal by becoming root and typing:

# killall -HUP inetd

On Solaris, killall kills all of the processes running, so do not run killall on the Solaris platform by mistake.

See also

• List of well-known ports

External links

• The ECHO process - RFC 347
• The ECHO protocol - RFC 862

Internet protocols