title: UDP tracker
text: # UDP tracker
  
  The UDP tracker protocol is a high-performance low-overhead BitTorrent tracker protocol. It uses the stateless User Datagram Protocol (UDP) for data transmission instead of the HTTP protocol (over TCP) regular trackers use. The data is in a custom binary format instead of the standard bencode algorithm BitTorrent uses for most communication.
  
  URLs for this protocol have the following format: udp://example.com:port.
  
  ## Comparison with the HTTP tracker
  
  The UDP tracker is better optimized and puts less strain on the tracking server. Neither tracker has any effect on transfer speeds.
  
  ## Clients implementing the protocol
  
  * BitComet
  * BitLord
  * BitRocket
  * BitSpirit
  * Deluge
  * FlashGet
  * KTorrent
  * libbt
  * Libtorrent (Rasterbar)
  * qBittorrent
  * rtorrent (implementing libTorrent (Rakshasa))
  * μTorrent
  * Turbo Torrent
  * Vuze
  * XBT Client
  * MLDonkey
  * Transmission
  * Tixati
  
  ## Criticisms
  
  * Limited IPv6 support (the protocol specifies a 32-bit integer for the IP address and supports pseudo-headers for 128-bit IPv6 addresses)
  * No mechanism for index sites to scrape an entire tracker
     * This can be supported by traditional TCP scrape mechanisms, as it's not a performance issue.
  * No mechanism for trackers to enforce client restrictions
  * The UDP tracker protocol has no field to represent the user agent, as the HTTP protocol has. However, the convention to encode the user agent and version inside the peer_id field still applies.
  * No mechanism for trackers to send warning messages
  * No compression, especially problematic for large announce responses.
  