Q & A on ICMP and UDP "ping",

Q: Touching the subject "source for ping" I think that could be useful to cite an article of Eric T. Horne, published by SysAdmin in the July/August 1993 issue, where he shows the source code for a newping that uses the TIME/TCP port, instead of the traditional ICMP, to detect CPU activity for the destination machine. I hope this citation be useful.

A: Actually, one doesn't need to use the time port because both TCP and UDP have a standard port reserved for echo: port 7. A program called ``upds'' has been floating around for many years that uses the UDP echo port exactly like ping uses ICMP echo. In fact, when I lecture to professional audiences, I usually talk about udps and explain that unlike ping, it determines more than whether interrupts are working on the remote computer.