EETimes India - November 16, 2008 - (Page 10)

In Focus | Data acquisition Working with IT for networked DAQ continued from page Many corporate IT departments employ additional utilities to improve the performance, security, and scalability of their networks. A managed Ethernet switch (MES) can provide quality of service (QoS), authentication and virtual LAN (VLAN) features through a programmatic (SNMP) or configurable (Web page) interface. Security Standard WEP WPA WPA2 (IEEE 802.11i) Encryption 64-bit key (RC4 cipher) 128-bit TKIP (RC4 cipher) 128-bit AES Authentication 64-bit key 802.1X and EAP 802.1X and EAP Table: The three levels of Wi-Fi network security. Wireless Networking Wi-Fi is an extension of the LAN to the wireless domain (WLAN). Wi-Fi technology has simplified the installation and distribution of networking infrastructure by replacing wire cabling with low-power radio waves. Because it is standards-based, it is widely available and integrates seamlessly with existing Ethernet networks. For wireless data acquisition, Wi-Fi is an easy way to tie into existing corporate infrastructure without special gateways or converters. With the most current ratified IEEE standard, IEEE 802.11g, it also provides ample bandwidth (54Mbps) for streaming dynamic waveform data. Security is foremost on the minds of network administrators when implementing Wi-Fi in a corporate environment. Because Wi-Fi transmits data over radio waves, there are few means for physically restricting network access. Generally speaking, there are three levels of wireless security: Wired Equivalent Privacy (WEP), Wireless Protected Access (WPA) and Wireless Protected Access 2 (WPA2, also known as IEEE 802.11i). WEP is considered to be too weak for almost all IT networks. Most use WPA or WPA2 instead. The differences between these standards are in how they implement the two key components of wireless security: encryption and authentication (see table). For effective protection of wireless transmissions, a wireless DAQ device must use a strong encryption algorithm and some form of key management. Two encryption standards widely in use today are the Temporal Key Integrity Protocol (TKIP) and the Advanced Encryption Standard (AES). The IEEE 802.11i task group introduced TKIP as a stopgap for existing, insecure WEP networks. The major difference between WEP and TKIP is in their encryption key management. The key Figure 2: Adding Wi-Fi to a wired network requires a wireless access point (WAP). is the “secret” that both a Wi-Fi data acquisition device and a wireless access point share to decode messages. Unlike WEP, TKIP uses a different encryption key for each data packet by incrementing a serial number associated with the key each time a new packet is sent. The most secure wireless standard, IEEE 802.11i, employs AES as the preferred encryption algorithm for Wi-Fi networks. AES uses a 128-bit cipher that is significantly stronger than the RC4 cipher used with TKIP and WEP. Also, there is no known crack for AES. In fact, AES is so strong that the National Institute of Standards and Technology (NIST) chose it as the encryption standard recommended for United States government installations. Network authentication is essentially a means of controlling which clients have access to a network and which do not. The WEP encryption key also functions as a password to authenticate with a wireless access point. Because most hackers have learned to exploit this behaviour, WPA and WPA2 use IEEE 802.1X port-based access control and the extensible authentication protocol (EAP) instead. IEEE 802.1X includes three main components: a supplicant, authenticator and authentication server. The supplicant is the wireless DAQ device attempting to access the secured network, the authenticator is the wireless access point that controls what a supplicant can access, and the authentication server provides an authentication service (usually RADIUS) to the authenticator. The authenticator blocks ports that provide access to the secured network until a sup- plicant has authenticated with the server. The process by which a WiFi DAQ device authenticates with an authentication server depends on the type of EAP method deployed by your IT depar tment. EAP defines a framework for authentication, rather than a specific stepby-step protocol. As a result, there are multiple EAP methods, but the most common include LEAP (lightweight EAP), EAP-TLS (transport layer security), EAPTTLS (tunnelled TLS), and PEAP (protected EAP). Note that different EAP methods require different user credentials. You must ask your network administrator for the appropriate user name, password, and/or certificate(s) you need to authenticate a client with your corporate network. Summary Industry standard Wi-Fi and Ethernet technology provide remote measurements beyond the reach of traditional PC-based data acquisition hardware. However, using existing corporate infrastructure for measurement applications may require the approval of an IT department. Wireless and Ethernet DAQ devices incorporate features familiar to both IT and engineering personnel. Once you understand how to communicate, working with your IT group can greatly simplify the addition of wireless and Ethernet measurements to existing networks. Online Design considerations for distributed test systems Test data provides yield improvement metrics 10 EE Times-India | November 16-30, 2008 | www.eetindia.com http://www.eetindia.co.in/article/email_friend.php3?article_id=8800515679&type=TA&cat_id=1800000&back_url=%2Farticle%2Farticle_content.php3%3Fin_param%3D8800515679_1800000_TA_427b9233%26 http://www.eetindia.co.in/SEARCH/SUMMARY/technical-articles/WLAN.HTM?ClickFromNewsletter_081116 http://www.eetindia.co.in/article/email_friend.php3?article_id=8800515679&type=TA&cat_id=1800000&back_url=%2Farticle%2Farticle_content.php3%3Fin_param%3D8800515679_1800000_TA_427b9233%26 http://www.eetindia.co.in/article/email_friend.php3?article_id=8800515679&type=TA&cat_id=1800000&back_url=%2Farticle%2Farticle_content.php3%3Fin_param%3D8800515679_1800000_TA_427b9233%26 http://www.eetindia.co.in/ART_8800522178_1800003_TA_5fda5187.HTM?ClickFromNewsletter_081116 http://www.eetindia.co.in/ART_8800545420_1800003_TA_399a4bab.HTM?ClickFromNewsletter_081116 http://www.eetindia.com/STATIC/REDIRECT/Newsletter_081116_EETI02.htm?ClickFromNewsletter_081116

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EETimes India - November 16, 2008 Contents Farnell Embedded System Eases Rail Maintenance National Semiconductor Working With IT for Networked DAQ Digital Telemetry Advances Torque Measurement Events

EETimes India - November 16, 2008

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