Quote:
    Originally posted by MrJoe    
It is perfectly valid to run a gnutella client on any port you want. However, with banning ports in the lower range it is likely to also ban valid alternate locations.   
I think it is essential that clients implement both X-Alt and X-Nalt, (X-Nalt are the locations which are known to be bogus). 
Gtk-gnutella emits both, but currently doesn't use the X-Nalt part itself yet.   |  
 
  So, If one wants to flood someone's HTTP server logs with "GET /uri-res/N2R/" requests, one is able just make bogus X-Alt (Alternate locations) replies with hits of most common requested files and there is nothing anyone can do about it except find the IP-addresses of those hosts and ban them from gnet?  
Yet if the servents get X-Nalt information from some other servants telling victim.host.com:80 is bogus, they still have to decide which one to believe. If they blindly trust X-Nalt fields, then one can use that to cause DoS to valid gnet-servants also. 
I think there is a risk someone starts to use gnet for DDOS with this feature.