CHARGEN

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The CHARGEN (character generator) service is an internet protocol defined in RFC 864. It is intended for testing and measurement purposes.

A host may connect to a server that supports the CHARGEN protocol, on either TCP or UDP port 19. Upon opening a TCP connection, the server starts sending arbitrary characters to the connecting host and continues until the hosts closes the connection. In the UDP version of the protocol, the server sends an UDP packet containing a random number (between 0 and 512) of characters every time it receives an UDP packet from the connecting host. Any data received by the server is thrown away.

Current testing and measurement of IP networks is more commonly done with ping and traceroute.

[edit] Uses

  • Was used maliciously to crash MS DNS servers running Microsoft Windows NT 4.0 by piping the arbitrary characters straight into the port the DNS server listens on (telnet ntbox 19 | telnet ntbox 53)

[edit] External links

  • The Character Generator Protocol (RFC 864)
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