DC++

Multiple connections from same user on same hub

Asked by Ayo

(This is a technical question :-)

I'm developing a new DC client (NMDC for now), and recently used it to try sharing some files on a few public hubs and see how well things would work. My client checks that there is at most one connection with the same user on the same hub. However, I've noticed that one user, advertising itself with a "++ V:0.782" tag, sent a $ConnectToMe even though we were already connected - according to my client, at least.

This makes me wonder about a few things:
- For what reason could a user have more than one connection with the same client?
- What does DC++ do in such a situation?

Thanks in advance!

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eMTee (realprogger) said : 		#1

- For what reason could a user have more than one connection with the same client?

Most probably to use your client for a dos attack of the IP sent with the ctm command.

- What does DC++ do in such a situation?

Verifies if the target is not the ip of a few known services in the DC network, if so then blocks the ctm, else it does nothing.

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Ayo (blicky) said : 		#2

Heh, that's a rather extreme situation. From what I've observed it didn't seem like an attempt to DoS someone. The connected party did reply with a $MyNick, and that's when my client checked for a duplicate connection with that nick on that particular hub and found out that it was already uploading a file to that user. That triggered me to wonder about why it was requesting another $ConnectToMe.

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eMTee (realprogger) said : 		#3

Alright, I mentioned the most probable case that can be thought of if someone has problems with nmdc ctm, as this is one of the several weaknesses of the nmdc protocol.

As nmdc is only a frozen legacy feature in DC++, you'd better find some other forums or maybe visit the dc development hub with this question where you may find people still actively chewing on nmdc (CZDC++, PtokaX, FlexHub... these coming to my mind atm) and you may get a proper answer there...

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