Siemens CP 1515 - Manual (Page 176)

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176 Industrial Ethernet Wireless LAN RLM Manager, CP 1515 Manager
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Like with other properties, your WEP lock is as safe as locking the door to
your house: i.e. if you don’t stick to secure policies on who will be allowed to
use the key, or will know where to find it, even the strongest lock can be
opened by an intruder.
That's why, for example you wouldn't “hide” the key to your house
underneath the doormat. Similar good practice should be applied to the keys
you will use to encrypt wireless communications.
To minimize the risk that intruders might be able to retrieve the WEP key
values you are advised to:
• Lock away any paper registration sheet that you use to define/remember
the defined WEP key values.
• Change the WEP encryption key values at regular intervals on both
stations and Radio Link Modules.
The option to enter up to 4 different keys to decrypt data received via the
wireless interface, enables you to define a WEP key roll-over scheme.
For example you could choose to select another transmit key every x weeks,
until you reach the fourth key. At that point in time you could enter 3 new
WEP key values for the first three WEP key entries, prior to the expiration
period of the fourth key value. Once all stations and Radio Link Modules
have been set to use the first new key again, you can replace the fourth key
value with a new WEP key value.