Lecture 5th October 2009

This lecture was talked about the wireless security. IEEE ratified 802.11 in 1997 and also known as Wi-Fi. 802.11 focus on Layer 1 & Layer 2 of OSI model which are physical layer data link layer. The wireless IEEE 802.11 standard offers two modes of operation for a wireless network; the Ad-Hoc mode and the Infrastructure mode. Infrastructure mode is used to connect computers with wireless network adapters, also known as wireless clients, to an existing wired network with the help from wireless router or access point. Ad hoc mode is used to connect wireless clients directly together, without the need for a wireless router or access point. An ad hoc network consists of up to 9 wireless clients, which send their data directly to each other.

For RTS / CTS, it is used to handle hidden nodes, sending station sends, access point responds with “Clear to Send”. Besides that, RTS / CTS is only used for larger pieces of data when retransmission may waste significant time. 802.11b is an extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission with a fallback to 5.5, 2 and 1-Mbps in the 2.4 GHz band. 802.11b uses only DSSS. 802.11b was 1999 ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet. In the other hand, 802.11a is an extension to 802.11 that applies to wireless LANs and provides up to 54-Mbps in the 5GHz band. 802.11a uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS. For 802.11g, it is applies to wireless LANs and is used for transmission over short distances at up to 54-Mbps in the 2.4 GHz bands.

Open System Authentication (OSA) is a process by which a computer can gain access to a wireless network that uses the Wired Equivalent Privacy (WEP) protocol. For OSA to work, the service set identifier (SSID) of the computer should match the SSID of the wireless access point.Access points have Access Control Lists (ACL). ACL is list of allowed MAC addresses but MAC addresses are sniffable and spoofable.

Mr. Zaki had explained the three basic security services defined by IEEE for the WLAN environment in 802.11 wireless LAN are authentication, integrity, and confidentiality. Besides that, there are 2 security services are provided in 802.11b which are authentication included Shared Key Authentication and Encryption included Wired Equivalence Privacy. Moreover, RC4 is Ron’s Code number 4 that can use key sizes from 1 bit to 2048 bits.RC4 will generates a stream of pseudo random bits.

Wired Equivalent Privacy (WEP) is a security protocol for Wi-Fi networks. WEP was designed to provide the same level of security that a wired network provides. It provides security by encrypting data over the radio waves. For example, in order to have a more secure Wi-Fi network connection, it's important to enter a WEP key to protect your data. There are some WEP Security tools such as AirSnort and WEPCrack. AirSnort is a wireless LAN (WLAN) tool which cracks encryption keys on 802.11 WEP networks. AirSnort operates by passively monitoring transmissions and computing the WEP encryption key when enough packets have been gathered. Furthermore, WEPCrack is a tool that cracks 802.11 WEP encryption keys by exploiting the weaknesses of RC4 key scheduling.

In the end of this lecture, Mr. Zaki said he will show us how to hack the wireless in the tomorrow lab. It is just a demo and he hopes us do not use abuse.