Eggheads: Problem with DCC CHATting to eggdrop 1.6.15 from same Internet connection

Paul T Wang eggdrop at paultwang.com
Sun Sep 14 18:21:35 CST 2003


>  RE: Problem with DCC CHATting to eggdrop 1.6.15 from same Internet
>  connection
>
> I'm using the eggdrop bot v1.6.15...
>

To summerize your problem, your home LAN is on NAT with DHCP or Static
(which probably doesn't concern eggdrop) with a gateway/router.

What are uncertain:
Which device is exposed to the Internet?
Does the gateway/router honor your IRC client as a server?

What might be the problem:
In normal route tables, your own Internet address (example: 1.3.3.7) is
automatically routed as a loopback. It acts like 127.0.0.1. However, because
your network setup is unknown, I can't comment on this possible problem.

So:
1. Your IRC client on Computer A sends a DCC CHAT
    request via IRC with your external IP and external port.
2. Your eggdrop sitting on Computer B telnets to
    <external_ip>:<external_port>
3. IF Computer B is directly connect to the Internet
THEN it loops external_ip right back to itself...
        Effectively, it telnets 127.0.0.1:<external_port>
        which doesn't work
ELSE it connects to <external_ip>:<external_port>
        4. *Some routers are not happy with an external
             loopback (requests to connect to itself from
            internal to external) and might do strange things*
        5. Assuming your router/gateway is smart and handles
            the request properly, it will connect right back to...
            err... which local IP is the server? The router has to
            know Computer A:port X is the server in order to
            forward the packets to Computer A:port X.


> Is there a particular port that DCC CHAT uses?
>

Consult with your IRC client manual. Most IRC clients are able to specify a
DCC port range for CHAT and SEND. If you are behind a NAT router, you must
make use of this feature to chat/send things out.



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