Wireless Security

1. Wireless Security 2005. 05. 31 교육대학원 분산시스템특론 인천대학교 민병준 032-770-8497, 011-9913-8497, bjmin@incheon.ac.kr

2. Contents • Introduction to Wireless • Wireless World • Wireless Threats • Wireless Security Protocols and Cryptography • Security Considerations for Wireless Devices • Wireless Technologies and Applications • Cellular Networks • Wireless Data Networks • Wireless Standards and Technologies • Wireless Deployment Strategies • Implementing Wireless LANs : Security Considerations • Enabling Secure Wireless Access to Data • Real Examples from the Wireless World • The Wireless Future • Accessing Wireless LANs

3. Wireless Standards and Technologies (1/3) • Current and Future Technologies • Infrared (IR) • close to visible light lends : straight line, bounce off objects • Radio • Most of the usable radio spectrum has already been allocated for specific uses. • ISM (industrial, scientific, and medical field) band - 2.4GHz • UNII (Unlicensed National Information Infrastructure) - 5GHz • existing LAN - 2.4GHz • Spread Spectrum • uses multiple frequencies (wideband) • FHSS (Frequency Hopping Spread Spectrum) : hopping from one frequency to another in pre-arranged synchronized patterns • DSSS (Direct Sequence Spread Spectrum) : spreading data by combining it with a multi-bit pattern or pseudo-noise code • OFDM (Orthogonal Frequency Division Multiplexing) • multicarrier modulation method that divides a communications channel into a number of equally spaced frequency bands • Current and Future Standards • 802.11 • LMSC (Local and Metropolitan Area Networks Standards Committee) of IEEE Computer Society • interface between wireless clients and their network access points : PHY, MAC WEP (Wired Equivalent Privacy) • PHY • diffuse infrared, DSSS radio, FHSS radio transmission • 1 Mbps ~ 2 Mbps data rate • MAC • distributed mode (CSMA/CD) and centrally coordinated mode • extra functions (error recovery, roaming functionality, power conservation)

4. Wireless Standards and Technologies (2/3) • Current and Future Standards (cont) • 802.11b • approved std in Sept. 1999, 11M bps, 2.4 GHz • Complimentary Code Keying DSSS • 802.11b • approved std in Sept. 1999, 11 Mbps, 2.4 GHz • Complimentary Code Keying DSSS • 802.11a • 54 Mbps, 5 GHz, OFDM • WiFi5 • 5G Hz licensed in other countries, but cleaner transmission without inference from other devices (cordless phones, microwave ovens, bluetooth) and 11 distinct channels compared with 3 channels for 2.4 GHz band • 802.11g • 22 Mbps, 54 Mbps OFDM with DSSS • interoperability with current 802.11b • same 2.4 GHz • 802.11j • joint IEEE, ETSI, Multimedia Mobile Access Communication (MMAC) 5 GHz Globalization and Harmonization Study Group (5GSG) • unifying the usage of band, but discontinued • 802.11e • for multimedia and voice over IP devices • 802.11i • temporal key integrity protocol • 128 bit temporal keys, fast packet keying and key management • 802.11f • roaming

5. Wireless Standards and Technologies (3/3) • Current and Future Standards (cont)) • IEEE 802.15 - WPAN : personal operating space 10m • TG 1 • based on Bluetooth 1.x with 1 Mbps • TG2 • interoperability between the 802.15 and 802.11 stds • TG3 • higher (20 Mbps or more) in WPAN, low cost low power operation • TG4 • lowering power consumption with low data rate (200 Kbps) for sensors, toys, smart badges, home automation • IEEE 802.16 -wireless MAN • TG 1 • PHY 10 to 66 GHz with 2 to 155 Mbps • Demand Assignment Multiple Access with TDMA • TG 2 • coexistence of broadband wireless access systems • TG 3 • operation in 2 to 11 GHz range • IEEE 802.1x - network port authentication • authentication framework using a variety of existing protocols for 802 based LAN • 128-bit keys for RC4 data encryption, encryption key rotation, blocking network activity • ETSI - European counterpart to IEEE • HiperLAN • Bluetooth • low-powered in 2.4GHz • very fast frequency hopping • 10 ~ 100 m • HomeRF - wideband frequency hopping • UWB • 3.1 through 10.6 GHz band, broadcast digital pulses, low power

6. Wireless LAN : Security Considerations • Common Wireless Network Applications • Physical Security Considerations • physical walkthrough, signal strength, AP placement evaluation, roaming clients • concealed or secured AP, directional antennae, metallic foil under the wall, named AP • Network Security Considerations • physical and data link layer control • 802.1x with dynamic WEP, which requires more back-end equipment and RADIUS (Remote Access Dial-In User Service) server with 802.1x capabilities • VPN tunneling - IPSec, Secure Shell • IDS • Application Security Considerations • WEP, IPSec / SSL, TLS, SSH • Enterprise Design • Access Network • DHCP/DNS server, VPN gateway, SSH server, NIDS, Terminal server for device management, AP's • Internal Network • Authentication server • Best Practices • segment the hostile wireless network from the rest of the internal network • disable the management of APs with the wireless interface • harden the DHCP/DNS server • SOHO Design • Access Network • Desktop, Firewall, Printer, AP • Best Practices • AP : use WEP and MAC access controls • Network host : add personal firewall • Turn off the equipment when is not in use

7. ZigBee/IEEE 802.15.4 - General Characteristics: • Dual PHY (2.4GHz and 868/915 MHz) • Data rates of 250 kbps (@2.4 GHz), 40 kbps (@ 915 MHz), and 20 kbps (@868 MHz) • Optimized for low duty-cycle applications (<0.1%) • CSMA-CA channel access Yields high throughput and low latency for low duty cycle devices like sensors and controls • Low power (battery life multi-month to years) • Multiple topologies: star, peer-to-peer, mesh • Addressing space of up to:- 18,450,000,000,000,000,000 devices (64 bit IEEE address)- 65,535 networks • Optional guaranteed time slot for applications requiring low latency • Fully hand-shaked protocol for transfer reliability • Range: 50m typical (5-500m based on environment)