How to Prevent or Block Rogue APs from Joining Your Wired or Wireless WLANs

Question

Hi all, I deployed a WLAN with 1 WLC 4400 and 5 1252AP. I do not see the way to Block Rogue APs from Joining the Wired or Wireless WLANs

Answer 1

PART 1
There are three parts to this:
1. detect - automatic
2. classify - by default APs are untrusted/unknown, various methods can be configured to classify them as trusted and threat (connected to wired network).
3. over the air contain (aka mitigate) - in 4.x this is manual, in 5.x you can configure auto-containment
First you need to detect. WLC does this automatically out of the box. It listens the air for unknown APs, clients and ad-hocs. Are you seeing Rogue APs under Monitor > Rogues > Rogue APs?
Next, you can manually classify rogue APs as "known" (internal or external). Starting with 5.0 you can also build rogue rules based on RSSI, SSID, Clients, etc. If an AP is classified as "known" (internal or external), WCS stops alerting you.
Another key classification piece is to detect whether or not the rogue AP is physically connected to your network which is a high security risk. There are three ways WLC can detect it and neither of them is automatic. You must configure these methods manually.
1. Rogue AP Detector, aka ARP sniffing. You have to dedicate one AP as "Rogue Detector" (change AP mode from local to rogue detector). Configure the port the AP is connected to as switchport mode trunk (normally it's switchport mode access). Rogue Detector AP turns off and doesn't use its radios. When WLC detects rogue APs it can also detect the MAC addresses of any clients associated to that rogue APs, and the rogue detector AP simply watches each hardwire trunked VLAN for ARP requests coming from those rogue AP clients. If it sees one, WLC automatically classifies the rogue AP as "threat" indicating that the rogue AP is physically connected to your network. It doesn't actually do anything with the rogue AP, it simply classifies it and alerts you. Also, keep in mind that this method doesn't work if the rogue AP is a Wireless Router, because Wireless Routers NAT and ARP requests don't propagate to the wire.
2. RLDP. Rogue Location Discovery Protocol. This feature is by default turned off and can be enabled under Security > Wireless Protection Policies > Rogue Polices. This feature works only when the rogue SSID is open, meaning that it's not using WEP/WPA/802.1x. When you enable RLDP, your WLC will pick some AP (you can't pick manually) which hears Rogue AP traffic, it will temporarily shut off its radio, turn it into a client, and instruct it to associate to the Rogue AP as client (this is where the requirement comes in for the Rogue SSID to be open authentication). Once associated, AP gets a DHCP IP through Rogue AP, it then sends a special small UDP port 6352 RLDP packet to every possible WLC's IP address (mgmt ip, ap manager ip, dynamic int IPs). If WLC gets one of those packets, it means that rogue AP is physically connected to your network. This method will work when Rogue AP is a Wireless Router. But this method is not recommended. It has an adverse effect on your wireless clients because RLDP AP goes offline for a period of time disconnecting your clients and forcing them to associate to another AP. Also, keep in mind, that WLC runs this RLDP process *once* per detected rogue AP. It doesn't periodically do this, it only does it once. In some later WLC versions, you can configure RLDP to run only on "monitor mode" APs, eliminating impact on your clients. Also, you can manually trigger RLDP for a rogue AP from CLI "config rogue ap rldp initiate ". You can "debug dot11 rldp" to see the process.
3. Switchport Tracing (need WCS, and WLC 5.1). This is a later feature that requires WCS. You can add your Catalyst switches to WCS, and WCS will look at CDP information and MAC tables on your switches to detect whether or not Rogue AP is connected to your network. This works with secured and NAT rogues. You can also *manually* instruct WCS to shut down the switchport that Rogue AP is connected to.