1.. _dns-resolve-sample:
2
3DNS Resolve Application
4#######################
5
6Overview
7********
8
9This application will setup IP address for the device, and then
10try to resolve various hostnames according to how the user has
11configured the system.
12
13- If IPv4 is enabled, then A record for ``www.zephyrproject.org`` is
14  resolved.
15- If IPv6 is enabled, then AAAA record for ``www.zephyrproject.org`` is
16  resolved.
17- If mDNS is enabled, then ``zephyr.local`` name is resolved.
18
19Requirements
20************
21
22- :ref:`networking_with_host`
23
24- screen terminal emulator or equivalent.
25
26- For most boards without ethernet, the ENC28J60 Ethernet module is required.
27
28- dnsmasq application. The dnsmasq version used in this sample is:
29
30.. code-block:: console
31
32    dnsmasq -v
33    Dnsmasq version 2.76  Copyright (c) 2000-2016 Simon Kelley
34
35Building and Running
36********************
37
38Network Configuration
39=====================
40
41Open the project configuration file for your platform, for example:
42:file:`prj_frdm_k64f.conf` is the configuration file for the
43:ref:`frdm_k64f` board.
44
45In this sample application, both static or DHCPv4 IP addresses are supported.
46Static IP addresses are specified in the project configuration file,
47for example:
48
49.. code-block:: console
50
51	CONFIG_NET_CONFIG_MY_IPV6_ADDR="2001:db8::1"
52	CONFIG_NET_CONFIG_PEER_IPV6_ADDR="2001:db8::2"
53
54are the IPv6 addresses for the DNS client running Zephyr and the DNS server,
55respectively.
56
57DNS server
58==========
59
60The dnsmasq tool may be used for testing purposes. Sample dnsmasq start
61script can be downloaded from the zephyrproject-rtos/net-tools project area:
62https://github.com/zephyrproject-rtos/net-tools
63
64Open a terminal window and type:
65
66.. code-block:: console
67
68    $ cd net-tools
69    $ sudo ./dnsmasq.sh
70
71The default project configurations settings for this sample uses the public
72Google DNS servers.  In order to use the local dnsmasq server, please edit
73the appropriate 'prj.conf' file and update the DNS server addresses.  For
74instance, if using the usual IP addresses assigned to testing, update them
75to the following values:
76
77.. code-block:: console
78
79    CONFIG_DNS_SERVER1="192.0.2.2:5353"
80    CONFIG_DNS_SERVER2="[2001:db8::2]:5353"
81
82.. note::
83    DNS uses port 53 by default, but the dnsmasq.conf file provided by
84    net-tools uses port 5353 to allow executing the daemon without
85    superuser privileges.
86
87If dnsmasq fails to start with an error like this:
88
89.. code-block:: console
90
91    dnsmasq: failed to create listening socket for port 5353: Address already in use
92
93Open a terminal window and type:
94
95.. code-block:: console
96
97    $ killall -s KILL dnsmasq
98
99Try to launch the dnsmasq application again.
100
101For testing mDNS, use Avahi script in net-tools project:
102
103.. code-block:: console
104
105    $ cd net-tools
106    $ ./avahi-daemon.sh
107
108
109LLMNR Responder
110===============
111
112If you want Zephyr to respond to a LLMNR DNS request that Windows host is
113sending, then following config options could be set:
114
115.. code-block:: console
116
117    CONFIG_NET_HOSTNAME_ENABLE=y
118    CONFIG_NET_HOSTNAME="zephyr-device"
119    CONFIG_DNS_RESOLVER=y
120    CONFIG_LLMNR_RESPONDER=y
121
122A Zephyr host needs a hostname assigned to it so that it can respond to a DNS
123query. Note that the hostname should not have any dots in it.
124
125
126QEMU x86
127========
128
129To use QEMU for testing, follow the :ref:`networking_with_qemu` guide.
130
131
132FRDM K64F
133=========
134
135Open a terminal window and type:
136
137.. zephyr-app-commands::
138   :zephyr-app: samples/net/dns_resolve
139   :board: frdm_k64f
140   :goals: build flash
141   :compact:
142
143See :ref:`Freedom-K64F board documentation <frdm_k64f>` for more information
144about this board.
145
146Open a terminal window and type:
147
148.. code-block:: console
149
150    $ screen /dev/ttyACM0 115200
151
152
153Use 'dmesg' to find the right USB device.
154
155Once the binary is loaded into the FRDM board, press the RESET button.
156