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Emule 0.50A Process Response Packet Failed
Posted 09 June 2011 - 12:07 PM
hello, we are doing some research work in eMule-kad and have recorded all the packets including incoming and outcoming packets in a official eMule 0.50a client. In our log we find an interesting phenomenon where a specific contact use another udp port to reply our client`s request(for example KADEMLIA2_REQ). So in function CSearch::ProcessResponse(…), we cant find the corresponding contact that we have made a request to, and cant process this KADEMLIA2_RES packet correctly. We have investigated some network configure conditions, for example Cone NAT and Symmetric NAT. But these trial don’t make any sense and we cant explain it. Finally we just consider it is probable that there are two NAT device in the specific contact`s network environment，one for incoming packet and another for outcoming packet. As a countermeasure, for a specific response we firstly judge it by its ip and udp port, if failed, we only use ip. We have confirmed that there are scarcely two contacts having the same ip in a Search object.
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