Saturday, June 30, 2007

wireless networking basics

A little info about wireless networking;

ESSID : The Extended Service Set Identification (ESSID) simpliest way is the name of the Access Point.You see ESSID as the string when you search for the AP

BSSID : MAC address of AP.Its an id of AP.

Wireless Channels : Wireless AP and clients talks to each other by using 2.4-2.5 ghz radio signals by default.Its a standard at IEEE 802.11b/g.

Wireless Security Models : To provide security between access nodes, IEEE defined 2 ways of method : WEP and WPA.WPA is stronger than WEP and support 128 bit authentication keys.WEP is also easy to recover password by using programs such as aircack or airsnort etc..

This things generally happens when a wireless client(notebook etc) attemps to connect to a Open Security based(no key authentication) AP :
1-> Client sends a request to AP.
2-> The access point authenticates the client.
3-> Client connects to AP.

But if AP protected by a WEP connection turns this :

The following steps occur when two devices use Shared Key(WEP) Authentication:

1. The client sends an authentication request to the access point.

2. The access point sends challenge text to the station.

3. The station uses its configured 64-bit or 128-bit default key to encrypt the challenge text, and it sends the encrypted text to the access point.

4. The access point decrypts the encrypted text using its configured WEP key that corresponds to the station's default key. The access point compares the decrypted text with the original challenge text. If the decrypted text matches the original challenge text, then the access point and the station share the same WEP key, and the access point authenticates the station.Because of that it calls Shared Key.

5. The client connects to the network.

There is two way of key generation model at WEP : 64 bits or 128 bits.24 of 64 bits is using for a 40 bit key generation.That means only 5 character key (40bits) can be generated by 64 bit authentication...

WPA Based wifi Security

WPA security model highly increases wireless security against WEP.Unlikely WEP, TKIP method required at WPA security model.TKIP is the new encrypt algorithm stronger than WEP.At one day you can sniff and crack WEP key.But WPA requires to collect more than one million package and "handshakes" between client and AP.

that link may work :p

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