
I. Capturing packets with Wireshark/Tshark

   There are two ways of installing Wireshark/Tshark on Debian:

   I./a. Installing dumpcap and allowing non-root users to capture packets

      Members of the wireshark group will be able to capture packets on network 
      interfaces. This is the preferred way of installation if Wireshark/Tshark
      will be used for capturing and displaying packets at the same time, since
      that way only the dumpcap process has to be run with elevated privileges 
      thanks to the privilege separation[1].

      Note that no user will be added to group wireshark automatically, the 
      system administrator has to add them manually.

      The additional privileges are provided using the Linux Capabilities
      system where possible or using the set-user-id bit, where the Linux 
      Capabilities are not present (Debian GNU/kFreeBSD, Debian GNU/Hurd).

      Linux kernels provided by Debian support Linux Capabilities, but custom
      built kernels may lack this support. If the support for Linux
      Capabilities is not present at the time of installing wireshark-common
      package, the installer will fall back to set the set-user-id bit to
      allow non-root users to capture packets.

      If installation succeeds with using Linux Capabilities, non-root users
      will not be able to capture packets while running kernels not supporting
      Linux Capabilities.

    I./b. Installing dumpcap without allowing non-root users to capture packets

      Only root user will be able to capture packets. It is advised to capture
      packets with the bundled dumpcap program as root and then run 
      Wireshark/Tshark as an ordinary user to analyze the captured logs. [2]
      
      
   The installation method can be changed any time by running:
   dpkg-reconfigure wireshark-common


II. Installing SNMP MIBs

    SNMP [4] OIDs can be decoded using MIBs provided by other packages.
    wireshark-common suggests snmp-mibs-downloader which package can be used to
    download a set of common MIBs Wireshark/Tshark tries to load at startup.

    At the time of writing, MIBs are distributed under DFSG incompatible terms
    [5] thus snmp-mibs-downloader has to be in the non-free archive area.
    To keep wireshark in the main area [7], wireshark-common does not depend on
    or recommend snmp-mibs-downloader and as a result snmp-mibs-downloader is
    not installed automatically with wireshark.

    To make Wireshark/Tshark able to decode OIDs, please install
    snmp-mibs-downloader manually.

    To help Wireshark/Tshark to decode OIDs without having to install packages
    manually, please support the initiative of requesting additional rights
    from RFC authors [5].


   [1] http://wiki.wireshark.org/Development/PrivilegeSeparation
   [2] http://wiki.wireshark.org/CaptureSetup/CapturePrivileges
   [3] https://blog.wireshark.org/2010/02/running-wireshark-as-you
   [4] http://wiki.wireshark.org/SNMP
   [5] http://wiki.debian.org/NonFreeIETFDocuments
   [6] http://www.debian.org/doc/debian-policy/ch-archive.html#s-non-free
   [7] http://www.debian.org/doc/debian-policy/ch-archive.html#s-main
