firewall protocols

[Ted Gervais]

I have just discovered that people are not able to telnet to my system and 
I have been told that it is not because I don't have the necessary ports 
open but rather the problem is because of protocols??

I have no idea what this means and am wondering if someone could 
explain.  If it is needed I can supply a copy of my firewall  but was 
wondering first if anyone has heard of this.

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Ted Gervais,
Coldbrook, Nova Scotia, Canada