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accessing-nodes.rst - linguistic fine-tuning

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Steffen Möller 2015-01-26 01:29:49 +01:00
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docs/user/accessing-nodes.rst
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@ -1,46 +1,51 @@
Accessing running nodes
=======================
Within the mesh network all Nodes have IPv6 addresses and are treated like regular
computers - with a built-in WLAN device. Once we know the IPv6 address, one can
access the device - to initiate a firmware update, perform various sorts of maintenance
for customized setups, or to just look what is going on when a node does not perform
as expected.
Within the mesh network all nodes have IPv6 addresses and are treated like regular
computers - with a built-in WLAN device. Once we know their IPv6 address, the device
can be accessed. There are various motivations to access a router, e.g. to initiate
a firmware update, perform maintenance for customized setups, to investigate when
a node is not working as expected, to access data from
an external storage deviced, or tap into a sensor network attached to it, and be
it a mere web camera.
**Access** may mean a mere ``ping``/``traceroute`` to determine if a host can be reached.
**Access** in its simplest form may mean a mere ``ping``/``traceroute`` to determine if a host can be reached.
To truly enter a machine, one will use SSH. See :doc:`/user/authentication` for information
how to set it up.
How to find the IPv6 address of a desired node
----------------------------------------------
The IPv6 addresses of the nodes are static and derived from the MAC addresses.
The IPv6 addresses of the nodes are static and may be derived from their MAC addresses.
Consequently, one needs to determine the IPv6 address only once per device.
To find the IPv6 address one can:
To find the IPv6 address one can
* Look at the bottom of the device and find the MAC address there.
* Directly connect via LAN-Cable and use the **next_node** addresses (if configured).
*
There are rules for an automated transcription of MAC addresses into IPv6
addresses.
You can find one implementation with some description at `ben.akrin.com <http://ben.akrin.com/?p=1347>`_.
* Determine the IPv6 address via the device's MAC address.
The procedure is basically an insertion of ``ff:ef`` in the middle, some bit
swapping and adding ``fe80::`` as prefix.
*
You can find a node address if you know the IPv4 address of a client connected
to it. If you perform a ``batctl traceroute`` to that client from any other Node
in the mesh, the MAC address can be found in the last hub::
There are rules for an automated transcription of MAC addresses into IPv6
addresses. You can find an a web service at `ben.akrin.com <http://ben.akrin.com/?p=1347>`_.
The procedure is basically an insertion of ``ff:ef`` in the middle, some bit
swapping and adding ``fe80::`` as prefix.
To find this physical network address:
* Look at the bottom of the device and find a label with the MAC address there.
* You can find a node address if you know the IPv4 address of a client connected
to it. If you perform a ``batctl traceroute`` to that client from any other Node
in the mesh, the MAC address can be found in the last hub::
$ batctl traceroute 10.135.17.193
traceroute to 10.135.17.193 (26:a4:3c:f0:b5:0a), 50 hops max, 20 byte packets
1: 12:fe:ed:3b:3f:cb 22.418 ms 23.008 ms 24.980 ms
2: 26:a4:3c:f0:b5:0a 28.733 ms 26.018 ms 22.403 ms
*
Check response times - the nodes answering first are those connected directly
to the querying host::
* Directly connect via LAN-Cable and use the **next_node** addresses (if configured).
* Check response times - the nodes answering first are those connected directly
to the querying host::
$ ping6 -I bat0 ff02::2 | head -n 5
@ -50,13 +55,16 @@ To find the IPv6 address one can:
64 bytes from fe80::fa1a:67ff:fe31:69ca: icmp_seq=1 ttl=255 time=27.1 ms (DUP!)
64 bytes from fe80::12fe:edff:feaf:57cc: icmp_seq=1 ttl=255 time=27.5 ms (DUP!)
These addresses are local-link IPv6 addresses and can be contacted directly.
These addresses are local-link IPv6 addresses and can be contacted directly.
.. note::
WLAN and Ethernet are different devices, each with it's own MAC address.
WLAN and Ethernet are different network devices, each with it's own MAC address,
albeit wired up to the same machine.
It is expected that these MAC addresses are not always exactly the same as
the ones seen underneath the device. Only one of either devices is depicted.
These two MAC addresses are commonly not identical. Expect to find only one
of the two devices mentioned on a label. Worse - for the same device, its
reported MAC address may depend on if it is meshing via its WLAN device or
if it is contacting via VPN directly.
Contacting the device
---------------------
@ -78,3 +86,4 @@ For SSH, analogously do::
The authenticity of host 'fe80::12fe:edff:feaf:57cc%bat0 (fe80::12fe:edff:feaf:57cc%bat0)' can't be established.
RSA key fingerprint is 53:5c:ac:f8:65:74:0b:cb:a4:67:26:3a:f5:65:2f:77.
Are you sure you want to continue connecting (yes/no)?