BackUp Tape Coordinator (BUTC)

This protocol is used on Transarc DCE/DFS to control tapes on remote servers.
BUTC is a protocol to manage and automate backups in a DCE/DFS environment. It is used to talk to remote backup tape coordinators which manage the actual tape drives.


BUTC was originally a component in the AFS network protocol but was broken out into a separate protocol when AFS was reimplemented atop DCE/RPC i.e. DCE/DFS. Even in the DCE/RPC variant of the protocol it still contains some legacy commands and fields that stem from its origins in AFS.

Protocol dependencies

  • UDP: Typically, BUTC uses UDP as its transport protocol.

  • DCE/RPC: BUTC is implemented on top of DCE/RPC and will thus run ontop of all transports supported by DCE/RPC. It is, however, most commonly implemented on top of DCE/RPC over IP/UDP.

Example traffic

XXX - Add example traffic here (as plain text or Wireshark screenshot).


The BUTC dissector is (fully functional, minus one opcode). Since BUTC is implemented atop DCE/RPC the normal DCE/RPC service response time statistics thatEwireshark calculates will also apply for BUTC.

Preference Settings

There are no preference settings specific to BUTC. However since it is transported atop DCE/RPC preference options for DCE/RPC will apply to BUTC as well. When BUTC is implemented on top of UDP one can use the IP_Reassembly preferences to make Wireshark reassemble all fragments into one full BUTC PDU.

Example capture file

XXX - Add a simple example capture file to the SampleCaptures page and link from here. Keep it short, it's also a good idea to gzip it to make it even smaller, as Wireshark can open gzipped files automatically.

Display Filter

A complete list of BUTC display filter fields can be found in the display filter reference


Capture Filter

There is no capture filter for BUTC, but if you know which UDP port it is using you can capture on that instead.

External links


Imported from on 2020-08-11 23:11:40 UTC