Cisco Systems 3.2 Layer 3 Solutions, Rogue Access Point Solutions, Rogue Access Point Challenges

Chapter 5 Configuring Security Solutions

Cisco WLAN Solution Security

Layer 3 Solutions

The WEP problem can be further solved using industry-standard Layer 3 security solutions, such as VPNs (virtual private networks), L2TP (Layer Two Tunneling Protocol), and IPSec (IP security) protocols. The Cisco WLAN Solution L2TP implementation includes IPSec, and the IPSec implementation includes IKE (internet key exchange), DH (Diffie-Hellman) groups, and three optional levels of encryption: DES (ANSI X.3.92 data encryption standard), 3DES (ANSI X9.52-1998 data encryption standard), or AES/CBC (advanced encryption standard/cipher block chaining). Disabling is also used to automatically block Layer 3 access after an operator-set number of failed authentication attempts.

The Cisco WLAN Solution IPSec implementation also includes industry-standard authentication using: MD5 (message digest algorithm), or SHA-1 (secure hash algorithm-1).

The Cisco WLAN Solution supports local and RADIUS MAC (media access control) filtering. This filtering is best suited to smaller client groups with a known list of 802.11 access card MAC addresses.

Finally, the Cisco WLAN Solution supports local and RADIUS user/password authentication. This authentication is best suited to small to medium client groups.

Rogue Access Point Solutions

This section describes security solutions for rogue access points.

Rogue Access Point Challenges

Rogue access points can disrupt WLAN operations by hijacking legitimate clients and using plaintext or other denial-of-service or man-in-the-middle attacks. That is, a hacker can use a rogue access point to capture sensitive information, such as passwords and username. The hacker can then transmit a series of clear-to-send (CTS) frames, which mimics an access point informing a particular NIC to transmit and instructing all others to wait, which results in legitimate clients being unable to access the WLAN resources. WLAN service providers thus have a strong interest in banning rogue access points from the air space.

The Operating System Security solution uses the Radio Resource Management (RRM) function to continuously monitor all nearby access points, automatically discover rogue access points, and locate them as described in the “Tagging and Containing Rogue Access Points” section on page 5-3.

Tagging and Containing Rogue Access Points

When the Cisco WLAN Solution is monitored using WCS, WCS generates the flags as rogue access point traps, and displays the known rogue access points by MAC address. The operator can then display a map showing the location of the Cisco 1000 Series lightweight access points closest to each rogue access point, allowing Known or Acknowledged rogue access points (no further action), marking them as Alert rogue access points (watch for and notify when active), or marking them as contained rogue access points. Between one and four Cisco 1000 Series lightweight access points discourage rogue access point clients by sending the clients deauthenticate and disassociate messages whenever they associate with the rogue access point.

When the Cisco WLAN Solution is monitored using a GUI or a CLI, the interface displays the known rogue access points by MAC address. The operator then has the option of marking them as Known or Acknowledged rogue access points (no further action), marking them as Alert rogue access points (watch

Cisco Wireless LAN Controller Configuration Guide

OL-8335-02 5-3