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Old 08-16-2005, 12:41 PM   #1
Registered: May 2002
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telneting to a udp port.


itried to connect to an open ntp udp port on the server, although the port is open I couldnt telnet to this port.

is it true I cant telnet to a udp port?

thanks !

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Old 08-16-2005, 02:07 PM   #2
Registered: Jun 2005
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Use netcat with the -u option. See nc(1)
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Old 08-18-2005, 12:41 AM   #3
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UDP is a connectionless protocol which means it basically just sends packets out to the specified destination. TCP is connection-oriented which means it establishes a connection to the other end using the '3-way handshake'.

So it makes sense to apply the 'telnet' paradigm to TCP - you make connection to a specific host and port, you still remain connected (for a period of time) even if you aren't sending any data and you can send and receive data continuously without having to reconnect in between.

UDP on the other hand doesn't really fit the telnet model - its more of a fire-and-forget system where you fire-off a series of packets towards the destination. You then go on with something else (or just wait doing nothing) until (or if) the remote process sends some packets back.
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Old 03-06-2013, 01:30 PM   #4
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Thumbs up

This is one of the most basic and useful exlplanations on UDP I've ever read in any forum. Anywhere ! Great Job tkedwards !!! And thank you for contributing to this community.


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