There are some torrent clients/agents that download sequentially and don't seem to upload at all. The last one I can remember is Xunlei (https://en.wikipedia.org/wiki/Xunlei#File_sharing)
Could you developers please add another option for the firewall, allowing for blocking clients/agents that match specific string, string pattern (xun*), and regex?
Currently the firewall only works with ip list or country codes. Since the client/agent information is already available (after all Tixati shows this information for all peers connected to us), and the firewall feature already exists, I presume this is reasonably feasible.