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<!--
- Copyright (C) 2015-2018 Internet Systems Consortium, Inc. ("ISC")
-
- This Source Code Form is subject to the terms of the Mozilla Public
- License, v. 2.0. If a copy of the MPL was not distributed with this
- file, You can obtain one at http://mozilla.org/MPL/2.0/.
-->
<!-- Converted by db4-upgrade version 1.1 -->
<chapter xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="faq">
<title>Frequently Asked Questions</title>
<para>This chapter contains a number of frequently asked questions and
troubleshooting tips. It currently lacks content, but it is expected to grow
over time.</para>
<!-- Note: you may be tempted to put in questions here that concern current
missing features or known issues type of stuff. Please do not do that.
This section should only contain questions that will still be valid in
at least 2 years. If you have something short term, please consider putting
it in the known issues list. -->
<section xml:id="faq-generic">
<title>General Frequently Asked Questions</title>
<section xml:id="q1-generic">
<title>Where did the Kea name came from?</title>
<para>Kea is the name of a high mountain parrot living in New Zealand.
See this <uri xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://lists.isc.org/pipermail/kea-users/2014-October/000032.html">https://lists.isc.org/pipermail/kea-users/2014-October/000032.html</uri>
for an extended answer.</para>
</section>
<section xml:id="q2-generic">
<title>Feature X is not supported yet. When/if will it be available?</title>
<para>Kea is developed by a small team of engineers. Our resources are
limited, so we need to prioritize requests. The complexity of a new
feature (how difficult it is to implement a feature and how likely it
would break something that already works), amount of work required and
expected popularity (i.e., how many users would actually benefit from it)
are three leading factors. We sometimes also have contractual obligations.
</para>
<para> Simply stating that you'd like feature X is useful. We try to
implement features that are actively requested first, but the reality
is that we have more requests than we can handle, so some of them must
be postponed, at least in the near future. So is your request likely to
be rejected? Not at all. You can do many things to greatly improve the
chances of your request being fulfilled. First, it helps to explain why you
need a feature. If your explanation is reasonable and there are likely
other users that would benefit from it, the chances for Kea developers
to put this task on a roadmap is better. Saying that you are willing
to participate in tests (e.g., test engineering drops when they become
available) is also helpful.</para>
<para>Another thing you can do to greatly improve the chances of a feature
to appear is to actually develop it on your own and submit a patch.
That's an avenue that people often forget about. Kea is open source
software and we do accept patches. There are certain requirements, like
code quality, comments, unit-tests, documentation, etc., but we have
accepted a significant number of patches in the past, so it's doable.
Accepted contributions range from minor documentation corrections to
significant new features, like support for a new database type. Before
considering writing and submitting a patch, make sure you read
the Contributor's Guide in the
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://git.kea.isc.org/~tester/kea/doxygen/">Kea Developer's Guide</link>.
</para>
<para>Kea is developed by ISC, which is a non-profit organization.
You may consider signing a development contract with us. In the past
we did implement certain features due to contractual obligations.
With additional funds we are able to put extra engineering efforts
into Kea development. We can reshuffle our schedule or add extra
hands to the team if needed. Please keep in mind that Kea is
open source software and its principle goal is to provide a good DHCP
solution that can be used by everyone. In other words, we may
refuse a contract that would tie the solution to specific proprietary
technology or make it unusable for other users. Also, we strive to
make Kea a reference implementation, so if your proposal significantly
violates a RFC, we may have a problem with that. Nevertheless, please
talk to us and we may be able to find a solution.</para>
<para>Finally, Kea has a <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://kea.isc.org/roadmap">public
roadmap</link>, with releases happening several times each year. We tend
to not modify plans for the current milestone, unless there are very good
reasons to do so. Therefore "I'd like a feature X in 6 months" is much
better received than "I'd like a feature X now".</para>
</section>
</section>
<section xml:id="faq-dhcp4">
<title>Frequently Asked Questions about DHCPv4</title>
<section iq="q1-dhcp4">
<title>I set up a firewall, but the Kea server still receives the traffic. Why?</title>
<para>Any DHCPv4 server must be able to receive from and send traffic to
hosts that don't have an IPv4 address assigned yet. That is typically not
possible with regular UDP sockets, therefore the Kea DHCPv4 server uses raw
sockets by default. Raw sockets mean that the incoming packets are received
as raw Ethernet frames, thus bypassing the whole kernel IP stack, including
any firewalling rules your kernel may provide.</para>
<para>If you do not want the server to use raw sockets, it is possible to
configure the Kea DHCPv4 server to use UDP sockets instead. See <command>dhcp-socket-type</command>
described in <xref linkend="dhcp4-interface-configuration"/>. However,
using UDP sockets has certain limitations. In particular, they may not allow
for sending responses directly to clients without IPv4 addresses assigned.
That's ok, if all your traffic is coming through relay agents.</para>
</section>
</section> <!-- end of DHCPv4 FAQ section -->
<section xml:id="faq-dhcp6">
<title>Frequently Asked Questions about DHCPv6</title>
<section iq="q1-dhcp6">
<title>Kea DHCPv6 doesn't seem to get incoming traffic. I checked with tcpdump (or other traffic
capture software) that the incoming traffic is reaching the box. What's wrong?</title>
<para>Please check whether your OS has any IPv6 filtering rules. Many
operating systems are shipped with firewalls that discard incoming IPv6
traffic by default. In particular, many Linux distributions do that. Please
check the output of the following command:
<screen>
# <userinput>ip6tables -L -n</userinput></screen>
One common mistake in this area is to use <command>iptables</command> tool,
which lists IPv4 firewall rules only.
</para>
</section>
</section> <!-- end of DHCPv6 FAQ section -->
</chapter>
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