APPENDIX E
SECURITY
Revised: 9 Sep 11
APX E-2
EST P/N AA107A
128-BIT WEP
The 128 WEP uses a particular algorithm called RC4 encryption to encode and decode traffic that is based on a 104-bit encryption
key and a 24-bit Initialization Vector (IV). RC4 starts with a relatively short encryption key (104 bits) that is expanded into a
nearly infinite stream of keys to accompany the stream of packets.
The basic concept of RC4 is good, but the way it’s implemented in WEP leaves it open to compromise. The researchers that test
the integrity of the system usually focus on one piece of the implementation, the Initialization Vector (IV).
The IV (24 bits) is the algorithm component that’s supposed to keep expanded keys from repeating. From the researcher’s point of
view, a high-volume access point is mathematically guaranteed to reuse the same key stream at least once a day. When this
happens, it’s called an IV collision this becomes a soft spot to enter the system.
The researchers aren’t saying that it’s easy to break into the system, or that it’s being done on a regular basis, only that it is possible
and that administrators should consider ways to reduce the possibility
ACCESS CONTROL LIST (ACL)
The ACL is one of the simplest yet most secure methods of network security. The ACL is a configurable MAC filter in the Model
192E that can be set to allow specific MAC address on the wireless network by individual address or address ranges. The same
filter can also be set to reject individual MAC addresses or address ranges.
The MAC address is a unique, 6 hexadecimal field address assigned at the manufacturer that can not be changed. The MAC
address is traceable through the IEEE governing body to the manufacturer and is the “fingerprint” for all Ethernet devices.
Using a combination of both the WPA or 128-Bit WEP encryption and the ACL filter provide the ESTeem an extremely secure
wireless networking layer.
DISABLING BROADCAST PROBES AND HIDING SSID
A simple but very effective way of securing a network is to make the network difficult to find. By disabling broadcast probes and
hiding the Service Set Identification (SSID), wireless and network “sniffers” will not be able to find your ESTeem Model 195Ea
network. To gain access to the wireless network, you would be required to have the SSID and all security loaded in the WLAN
card software prior to entering the network.
PROPRIETARY BRIDGE COMMUNICATION
Although the ESTeem Model 195Ea is compatible with the open communication standards IEEE 802.11g and 802.11b, the
repeater communication between the units is a proprietary communication link. No other manufacturer of wireless hardware can
access the ESTeem repeater network when bridging between Ethernet networks. This proprietary communication layer, in
combination with the other security settings, allows you as the user to reject wireless clients into the network if so desired. When
used in conjunction with the Access Control List the 802.11g and 802.11b client access can be removed.
The security level of the bridge communication link is configurable for 64-Bit WEP, 128-Bit WEP or TKIP and is completely
independent of the client access level or any other communication link level. For example, an ESTeem Model 195Ea can be
configured for WPA Enterprise for client level access, communicate to another ESTeem Model 195Ea using a TKIP bridge link
and also communicate 128-Bit WEP to our older ESTeem Model 192E radio modems all running simultaneously.