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DTUS065 rev A.7 – June 27, 2014
V.9
C-KEY handling
Some products of the product line can be equipped with a C-KEY.
The following applies to these products, when equipped with firmware
version 2.2.0 or greater.
Warning
: Unlike the “WLg” products series, the C-KEY is never saved or
updated automatically in the “WLn” products.
V.9.1
Factory settings
Since the firmware 2.4.0 the out of box C-KEY state has changed.
In this state (Factory state) the C-KEY LED is turned off and the C-KEY
contain not useable data.
After the C-KEY is initialized, there is no way to put back the C-KEY in this
state.
V.9.2
Understanding configurations and their signature
A C-Key contains:
-
a product model identifier;
-
an archive of the configuration files appropriate for the model;
-
a signature for the archive (the C-Key signature, a MD5 sum).
The product keeps an internal copy of the configuration files, so that it can
work with the C-Key removed. The internal copy also has a signature (the
internal signature), which is updated in 3 cases:
-
when the product is reset to factory settings, the internal signature is
cleared before rebooting;
-
when the user copies the internal configuration to the C-Key, the
internal signature is recomputed so that it is the same as the newly
created C-Key signature;
-
at boot time, when the C-Key signature is found different from the
internal signature, the C-Key configuration and its signature are
copied to the internal configuration (you can disable this copy using
either the web interface or SNMP).
This procedure has several consequences.
-
After a reset-to-factory-settings action, the product reboots and
copies the C-Key contents, if valid; to its internal configuration, and
uses it immediately; this is a sure path to ensure that the product is
using the C-Key configuration;
-
if you change the internal configuration, since the internal signature
is unchanged, the next reboot will not load from the C-Key; instead it
will use the changed configuration; this situation is shown with a
warning in the web interface; it is useful for lab testing;
-
if you replace the C-Key with another one containing a different
configuration (hence a different signature), it will clear and replace
your internal configuration at next power-on. This will not happen if
you have previously disabled the C-Key function.
