How does Echolink distinguish "incorrect
password" from other
conditions? Or does it assume that if a connection is dropped at a
certain stage, then it's an incorrect password?
Well my description was from memory and not entirely correct.
There are only two error codes that a proxy server can return to the client,
one for "bad password" and the other for "access denied"
(i.e. the presented callsign fails the check to the CallsignAllowed or CallsignDenied
patterns in the config, usually using wildcard checks like "deny -R" to deny
repeaters)
However, there is no error code for "proxy busy", a busy proxy simply
disconnects new users
before they even authenticate.
There is also no way to return an error message text, the error is returned as a code
and the client issues an appropriate message to the user.
So you cannot communicate a more detailed message like "this proxy is reserved for
...".
However, you can use a private proxy (different password) to achieve that.
But yes, good idea, I can block incoming connections
on TCP 8100 (proxy
port) on the IPs that conferences are using. Thanks for that suggestion.
Indeed, when you setup your firewall to just refuse connects from other systems they will
believe this proxy is busy. However, when the proxy used by the conference is private
and (nearly) always busy, there is not much you need to do as it works fine by default.
The worst that could happen is that someone DoS'es you by repeatedly trying to
connect
to the proxy at a time the conference server isn't connected and then proceed through
the authentication as slow as it can, and once it gets disconnected immediately
re-connect
before the conference had a chance to do that. I have not yet encountered such
behaviour.
Rob