The Tcpdump Group git mirrors - libpcap/blob - doc/DLT_ALLOCATE_HOWTO.md

   1 DLT and LINKTYPE allocation
   2 ===========================
   3
   4 DLT_ types live in pcap/dlt.h.  They can be requested by the community on a
   5 First-Come First-Served basis [i.e. https://tools.ietf.org/html/rfc8126#section-4.4 ]
   6 (Although libpcap is not at this time an IETF specification, there have been
   7 some as yet-incomplete efforts to do this).
   8
   9 The Tcpdump Group prefers to link to an open specification on the new DLT_
  10 type,  but they are available for closed, proprietary projects as well.
  11 In that case, a stable email address suffices so that someone who finds
  12 an unknown DLT_ type can investigate.
  13 We prefer to give out unambiguous numbers, and we try to do it as quickly
  14 as possible, but DLT_USERx is available while you wait.
  15
  16 Note that DLT_ types are, in theory, private to the capture mechanism and can
  17 in some cases be operating system specific, and so a second set of values,
  18 LINKTYPE_ is allocated for actually writing to pcap files.  As much as
  19 possible going forward, the DLT_ and LINKTYPE_ value are identical, however,
  20 this was not always the case.  See pcap-common.c.
  21
  22 The LINKTYPE_ values are not exported, but are on pcap-common.c only.
  23
  24 DEVELOPER NOTES
  25 ---------------
  26
  27 When allocating a new DLT_ value, a corresponding value needs to be
  28 added to pcap-common.c.
  29 It not necessary to copy to commonts from dlt.h to pcap-common.c.
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