Assigned Numbers

:Post-History:

This document describes the known bit allocations and message IDs for

the BitTorrent protocol. To request a bit allocation contact

editor@bittorrent.org. Contact the same address if you are aware of

any omissions.

Reserved Bit Allocations

 reserved[0]
 0x80  Azureus Messaging Protocol

reserved[2]

0x08 BitTorrent Location-aware Protocol (no known implementations)

reserved[5]

0x10 LTEP (Libtorrent Extension Protocol)

0x02 Extension Negotiation Protocol

0x01 Extension Negotiation Protocol

reserved[7]

0x01 BitTorrent DHT

0x02 XBT Peer Exchange

0x04 suggest, haveall, havenone, reject request, and allow fast extensions

0x08 NAT Traversal

0x10 hybrid torrent legacy to v2 upgrade

There are known collisions

 reserved[0]
 0xFF  BitComet Extension Protocol

reserved[1]

0xFF BitComet Extension Protocol

reserved[7]

0x01 XBT Metadata Exchange (implemented only in XBT)

It is recommended that further extensions use the Extension Protocol

[#BEP-10]_, a.k.a., LibTorrent Extension Protocol (LTEP). With LTEP,

extension bit collisions become impossible since no new extension bits

are allocated. With LTEP, message ID collisions also become

impossible because message IDs are allocated on demand at the

beginning of the connection. Extension name collisions become

possible, but the probability is much less likely.

Reserved Message IDs

 Core Protocol:
 0x00   choke
 0x01   unchoke
 0x02   interested
 0x03   not interested
 0x04   have
 0x05   bitfield
 0x06   request
 0x07   piece
 0x08   cancel

DHT Extension:

0x09 port

Fast Extensions:

0x0D suggest

0x0E have all

0x0F have none

0x10 reject request

0x11 allowed fast

Additional IDs used in deployed clients:

0x14 LTEP Handshake (implemented in libtorrent, uTorrent,...)

Hash Transfer Protocol:

0x15 hash request

0x16 hashes

0x17 hash reject

References

.. [#BEP-10] BEP_0010. Extension Protocol. Norberg, Strigeus, Hazel.

http://www.bittorrent.org/beps/bep_0010.html

Copyright

This document has been placed in the public domain.

..

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