.. _bluetooth-ipsp-sample:

Bluetooth: IPSP Sample
######################

Overview
********
Application demonstrating the IPSP (Internet Protocol Support Profile) Node
role. IPSP is the Bluetooth profile that underneath utilizes 6LoWPAN, i.e. gives
you IPv6 connectivity over BLE.

Building and Running
********************

This sample can be found under :file:`samples/bluetooth/ipsp` in the
Zephyr tree.

Testing with a Linux host
=========================

Make sure the Linux kernel has been built with Bluetooth 6LoWPAN module
(CONFIG_BT_6LOWPAN=y) then proceed to enable it with with the following commands
(as root):

.. code-block:: console

   # modprobe bluetooth_6lowpan
   # echo 1 > /sys/kernel/debug/bluetooth/6lowpan_enable

If you connected your board to a UART console, you will see an output similar to
(may vary slightly by application and Zephyr versions):

.. code-block:: console

   [bt] [WRN] set_static_addr: Using temporary static random address
   [bt] [INF] show_dev_info: Identity: cb:af:14:57:d8:6e (random)
   [bt] [INF] show_dev_info: HCI: version 5.0 (0x09) revision 0x0000, manufacturer 0xffff
   [bt] [INF] show_dev_info: LMP: version 5.0 (0x09) subver 0xffff
   [bt] [WRN] bt_pub_key_gen: ECC HCI commands not available
   [ipsp] [INF] init_app: Run IPSP sample
   [ipsp] [INF] listen: Starting to wait

The output above shows the BLE address assigned to your board for the
current session; the address will be different on subsequent sessions.

Alternatively, you may scan for your board on the host. The modern way to do
that is using ``bluetoothctl`` utility (included in the recent versions of
BlueZ package) and its ``scan on`` command:

.. code-block:: console

   $ bluetoothctl
   [NEW] Controller A3:24:97:EB:D6:23 ubuntu-0 [default]
   [NEW] Device D7:5C:D6:18:14:87 Zephyr
   [NEW] Device E1:E7:F9:56:EC:06 Zephyr
   [NEW] Device C8:12:C5:08:86:E1 Zephyr
   [bluetooth]# scan on
   Discovery started
   [NEW] Device DC:98:FB:22:CA:3A Zephyr

When started, ``bluetoothctl`` shows all BLE (and likely, BT/EDR) devices it
knows about. As discussed above, the IPSP uses static random addresses, so
entries for previously connected devices, as shown above, can accumulate and
become stale. You need to be extra careful to find an entry for the active
address. The best approach may be to reset your board after issuing
``scan on`` command. This way it will reinitialize with the BLE address
which will be discovered after the command.

As an alternative to ``bluetoothctl``, you can use the legacy ``hcitool``
utility which talks directly to hardware and always shows fresh scan results:

.. code-block:: console

   $ sudo hcitool lescan
   LE Scan ...
   CB:AF:14:57:D8:6E (unknown)
   CB:AF:14:57:D8:6E Test IPSP node

After you have found the board's BLE address, connect to the board (as root):

.. code-block:: console

   # echo "connect <bdaddr> <type>" > /sys/kernel/debug/bluetooth/6lowpan_control

Where ``<bdaddr>`` is the BLE address and ``<type>`` is BLE address type:
1 for public address and 2 for random address. As you can see from
the IPSP sample output above, it uses a static random address. So, with the
sample output above, the command will be:

.. code-block:: console

   # echo "connect CB:AF:14:57:D8:6E 2" > /sys/kernel/debug/bluetooth/6lowpan_control

Once connected a dedicated interface will be created, usually bt0. You can verify this
with the following command:

.. code-block:: console

   # ifconfig
   bt0       Link encap:UNSPEC  HWaddr F8-2F-A8-FF-FE-EB-6D-8C-00-00-00-00-00-00-00-00
             inet6 addr: fe80::fa2f:a8ff:feeb:6d8c/64 Scope:Link
             UP POINTOPOINT RUNNING MULTICAST  MTU:1280  Metric:1
             RX packets:2 errors:0 dropped:3 overruns:0 frame:0
             TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
             collisions:0 txqueuelen:1000
             RX bytes:92 (92.0 B)  TX bytes:233 (233.0 B)

As can be seen from the output, only a link-local IPv6 address was assigned
to the interface.

At this point, you can test IPv6 connectivity (and discover your board's IPv6
address) by pinging "All local-link nodes" IPv6 address:

.. code-block:: console

   # ping6 -I bt0 ff02::1
   PING ff02::1(ff02::1) from fe80::fa54:a8ff:feeb:218f bt0: 56 data bytes
   64 bytes from fe80::fa54:a8ff:feeb:218f: icmp_seq=1 ttl=64 time=0.088 ms
   64 bytes from fe80::c9af:14ff:fe57:d86e: icmp_seq=1 ttl=64 time=285 ms (DUP!)

For each ping packet, both your host and the BLE board send a reply. You
can see the board's reply marked as ``(DUP!)``. You can ping the board
directly with:

.. code-block:: console

   # ping6 fe80::c9af:14ff:fe57:d86e%bt0
   PING fe80::c9af:14ff:fe57:d86e%bt0(fe80::c9af:14ff:fe57:d86e) 56 data bytes
   64 bytes from fe80::c9af:14ff:fe57:d86e: icmp_seq=1 ttl=64 time=177 ms
   64 bytes from fe80::c9af:14ff:fe57:d86e: icmp_seq=2 ttl=64 time=53.0 ms

Note that the command uses a "scoped IPv6 address", where the scope is
defined by the networking interface, with ``%bt0`` appended in this case.
A specification like that is an alternative to passing ``-I bt0`` to
``ping6`` (and works with other networking tools like ``telnet``, ``nc``,
``curl``, etc.)

While we can use a link-local address, it's not very convenient, as it must be
scoped and will change on each run. Instead, the IPSP sample is configured with
``2001:db8::1`` static address and we'll configure the host's interface to
access that address by configuring ``bt0`` with the complementary address
``2001:db8::2``:

.. code-block:: console

   # ip address add 2001:db8::2/64 dev bt0

Now we can ping the board's static address with:

.. code-block:: console

   # ping6 2001:db8::1
   PING 2001:db8::1(2001:db8::1) 56 data bytes
   64 bytes from 2001:db8::1: icmp_seq=1 ttl=64 time=282 ms

The IPSP sample includes builtin echo server for UDP and TCP on a port 4242,
which we can test with:

.. code-block:: console

   $ telnet 2001:db8::1 4242
   Trying 2001:db8::1...
   Connected to 2001:db8::1.
   Escape character is '^]'.
   test
   test
   test2
   test2
   ^]
   telnet> quit
   Connection closed.

In the output above, first ``test`` line was typed, next was echoed back by
the board. Likewise for ``test2``. To quit telnet tool, type Ctrl+], then
"quit" at the prompt.

As an alternative to using well-known networking tools above, and also to
test both TCP and UDP echo, you can use Zephyr's helper tool in the GitHub
``zephyrproject-rtos/net-tools`` repository:

.. code-block:: console

   $ echo-client -i bt0 <ip>

.. note::

   For hosts using kernels released before 4.12 CONFIG_NET_L2_BT_ZEP1656
   shall be selected: https://github.com/zephyrproject-rtos/zephyr/issues/3111