[CALUG] open ports

[Walt Smith]

I enjoyed a great deal the openVPN session.

I was wondering what was meant by the term "open ports"?
I don't recall if an "Ethernet" driver actually listens
( is the sole accessor to directly listen to.. )
to all the ports.  Contrast to some "service" that does.
For example, port 23 would be a telnet server listening to
that port.  i.e does the telnet server get it's packets from
the ethernet driver ?

re-stated,
Is the telnet server the only software that directly accesses
the "port" itself ?  Seems to me in the OSI that the ethernet driver
is what resides and sucks out the packets.  

So, does "open port" mean the ethernet driver is actually listening ?
( is the only true connection/listener ).
Other than the listing of "ports" in the "services" file,
is that the config file that "permits"/"enables" the 
port ?  Is there a specific block to specific ports ?

Another POV, does stopping the telnet server mean port 23
is no longer "connected/used/accessible" ?  hence "safe"
from intrusion attempts ( other than a hole in the OS ) ?

thx,
Walt......



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