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 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:: The sample configuration file of NFD allow any user to manage faces, FIB, RIB, and
    StrategyChoice of the local NFD.  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 use commands Interests (e.g., FIB modification, Face
creation/destructions, etc.), which require an NDN certificate (either self-signed for local
trust or delegated from a trusted authority).

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 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`.