05 Aug, 2009, Erok wrote in the 1st comment:
Votes: 0
I thought it might be interesting to periodically measure the speed of a player's connection and show their "ping" time, in the "who" output for example.

It looks like measuring the time it takes to receive a response to an "are-you-there" in the telnet protocol is the most analogous mechanism to ICMP echo, but I'm thinking only standard telnet clients are likely to respond.

I suppose one could just repeat the telnet linemode request, which is probably close to being universally supported across clients, and measure the response time to that.

Thoughts or alternatives?
05 Aug, 2009, Kintar wrote in the 2nd comment:
Votes: 0
You could always pick a nonexistent telnet opcode and send an IAC+DONT+OPCODE message. Unless you stumble across someone's custom telnet option, almost any telnet client is going to send back IAC+WONT+OPCODE.