FAQ
===

How to change default paths?
----------------------------

Paths to where NFD is installed can be configured during ``./waf
configure``:

- Installation prefix (default ``/usr/local``):

    ::

        ./waf configure --prefix=/usr

- Location of NFD configuration file (default: ``${prefix}/etc``):

    ::

        ./waf configure --prefix=/usr --sysconfdir=/etc

- Location of manpages (default: ``${prefix}/share/man``)

    ::

        ./waf configure --prefix=/usr --sysconfdir=/etc --mandir=/usr/share/man

How to run NFD on Raspberry Pi?
-------------------------------

To run NFD on the Raspberry Pi, you need to either enable IPv6 support
in Raspberry Pi or disable IPv6 support in NFD.

To enable IPv6 in Raspberry Pi:

::

    sudo modprobe ipv6

To disable IPv6 in NFD, replace ``enable_v6 yes`` with ``enable_v6 no``
in ``tcp`` and ``udp`` sections of ``/usr/local/etc/ndn/nfd.conf``:

::

    ...
    tcp
    {
      listen yes
      port 6363
      enable_v4 yes
      enable_v6 no
    }

    udp
    {
      port 6363
      enable_v4 yes
      enable_v6 no
      idle_timeout 600
      keep_alive_interval 25

      mcast yes
      mcast_port 56363
      mcast_group 224.0.23.170
    }
    ...


How to run NFD as non-root user?
--------------------------------

How to configure automatic dropping of privileges?
++++++++++++++++++++++++++++++++++++++++++++++++++

NFD can be configured to drop privileges whenever possible.  You can specify a user and/or
group for NFD to change its *effective* user/group ID to in the ``general`` section of the
configuration file. For example:

::

    general
    {
      user nobody
      group nogroup
    }

will configure NFD to drop its effective user and group IDs to ``nobody`` and ``nogroup``,
respectively.

.. note::

    **IMPORTANT:** NFD may regain elevated permissions as needed during normal
    execution. Dropping privileges in this manner should not be considered a security
    mechanism (a compromised NFD that was started as root can trivially return to
    root). However, reducing privileges may limit any damaged caused by well intentioned,
    but buggy, code.


How to enable Ethernet Face Support?
++++++++++++++++++++++++++++++++++++

The ``ether`` configuration file section contains settings for Ethernet faces and
channels. These settings will **NOT** work without root or setting the appropriate
permissions:

::

    sudo setcap cap_net_raw,cap_net_admin=eip /full/path/nfd

You may need to install a package to use setcap:

**Ubuntu:**

::

    sudo apt-get install libcap2-bin

**Mac OS X:**

::

    curl https://bugs.wireshark.org/bugzilla/attachment.cgi?id=3373 -o ChmodBPF.tar.gz
    tar zxvf ChmodBPF.tar.gz
    open ChmodBPF/Install\ ChmodBPF.app

or manually:

::

    sudo chgrp admin /dev/bpf*
    sudo chmod g+rw /dev/bpf*

How to enable UDP multicast support in multi-homed Linux machines
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

The UDP configuration file section contains settings for unicast and multicast UDP
faces. If the Linux box is equipped with multiple network interfaces with multicast
capabilities, the settings for multicast faces will **NOT** work without root
or setting the appropriate permissions:

::

    sudo setcap cap_net_raw=eip /full/path/nfd

.. _How to configure NFD security:

How to configure NFD security?
------------------------------

.. note:: Sample configuration file of NFD allow any user to manage faces, FIB, RIB, and
    StrategyChoice.  The following description can be used to restrict certain operations
    to certain users.

    More extensive documentation about NFD's security and options to configure trust model
    for NFD is currently in preparation.

Many NFD management protocols require signed commands to be processed
(e.g. FIB modification, Face creation/destructions, etc.). You will need
an NDN certificate to use any application that issues signed commands.

If you do not already have NDN certificate, you can generate one with
the following commands:

**Generate and install a self-signed identity certificate**:

::

    ndnsec-keygen /`whoami` | ndnsec-install-cert -

Note that the argument to ndnsec-key will be the identity name of the
new key (in this case, ``/your-username``). Identity names are
hierarchical NDN names and may have multiple components (e.g.
``/ndn/ucla/edu/alice``). You may create additional keys and identities
as you see fit.

**Dump the NDN certificate to a file**:

The following commands assume that you have not modified ``PREFIX`` or
``SYSCONFDIR`` If you have, please substitute ``/usr/local/etc`` for the
appropriate value (the overriden ``SYSCONFDIR`` or ``PREFIX/etc`` if you
changed ``PREFIX``).

::

    sudo mkdir -p /usr/local/etc/ndn/keys
    ndnsec-cert-dump -i /`whoami` > default.ndncert
    sudo mv default.ndncert /usr/local/etc/ndn/keys/default.ndncert

.. _How to start using NDN MacPorts repository on OSX:

How to start using NDN MacPorts repository on OSX?
--------------------------------------------------

Please see :ref:`Install NFD Using the NDN MacPorts Repository on OS X and macOS`.

.. _How to start using NDN PPA repository on Ubuntu Linux:

How to start using NDN PPA repository on Ubuntu Linux?
------------------------------------------------------

Please see :ref:`Install NFD Using the NDN PPA Repository on Ubuntu Linux`.

.. _How to start using NDN Overlay on Gentoo Linux:

How to start using NDN Overlay on Gentoo Linux?
-----------------------------------------------

If you want to install NFD and other packages using Portage on Gentoo Linux, you can start
using NDN Overlay.

Simply checkout `NDN Overlay <https://github.com/Pesa/ndn-overlay>`_ repository to some
location add the checkout path to ``PORTDIR_OVERLAY`` in ``/etc/portage/make.conf``:

::

    cd /some/path
    git clone https://github.com/Pesa/ndn-overlay.git

    # and then add /some/path/ndn-overlay to PORTDIR_OVERLAY in /etc/portage/make.conf

Afterwards, you will be able to install ``nfd`` using standard mechanisms.