The Echo Protocol is a service in the
Internet Protocol Suite
The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the sui ...
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
The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is common ...
(TCP) or the
User Datagram Protocol
In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in packets) to other hosts on an Internet Protocol (IP) networ ...
(UDP) on the
well-known port number
In computer networking, a port is a number assigned to uniquely identify a connection endpoint and to direct data to a specific service. At the software level, within an operating system, a port is a logical construct that identifies a specific ...
7. The server sends back an identical copy of the data it received.
Inetd implementation
On
UNIX-like
A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...
operating systems an echo server is built into the
inetd family of
daemons. The echo service is usually not enabled by default. It may be enabled by adding the following lines to the file and telling inetd to reload its configuration:
echo stream tcp nowait root internal
echo dgram udp wait root internal
On various routers, this TCP or UDP port 7 for the Echo Protocol for relaying
ICMP datagrams (or port 9 for the
Discard Protocol
The Discard Protocol is a service in the Internet Protocol Suite defined in RFC 863. It was designed for testing, debugging, measurement, and host-management purposes.
A host may send data to a host that supports the Discard Protocol on either ...
) is also configured by default as a proxy to relay
Wake-on-LAN (WOL) magic packets from the Internet to hosts on the local network in order to wake them up remotely (these hosts must also have their network adapter configured to accept WOL datagrams and the router must have this proxy setting enabled, and possibly also a configuration of forwarding rules in its embedded
firewall to open these ports on the Internet side).
See also
*
Discard Protocol
The Discard Protocol is a service in the Internet Protocol Suite defined in RFC 863. It was designed for testing, debugging, measurement, and host-management purposes.
A host may send data to a host that supports the Discard Protocol on either ...
*
Daytime Protocol
The Daytime Protocol is a service in the Internet Protocol Suite, defined in 1983 in RFC 867. It is intended for testing and measurement purposes in computer networks.
A host may connect to a server that supports the Daytime Protocol on either T ...
*
QOTD
The Quote of the Day (QOTD) service is a member of the Internet protocol suite, defined in RFC 865. As indicated there, the QOTD concept predated the specification, when QOTD was used by mainframe sysadmins to broadcast a daily quote on request by ...
*
Character Generator Protocol
*
Time Protocol
The Time Protocol is a network protocol in the Internet Protocol Suite defined in 1983 in RFC 868 by Jon Postel and K. Harrenstein. Its purpose is to provide a site-independent, machine readable date and time.
The Time Protocol may be implemented ...
*
ICMP Echo Request
References
{{reflist
External links
RFC 347 Echo ProcessRFC 862 Echo Protocol
Application layer protocols