Detection of Rogue Access Points

Mon Oct 15 02:32:22 UTC 2012

On 10/14/2012 1:59 PM, Jonathan Rogers wrote:
> Gentlemen,
 >
 > An issue has come up in my organization recently with rogue access
 > points. So far it has manifested itself two ways:
 >
 > 1. A WAP that was set up specifically to be transparent and provided
 > unprotected wireless access to our network.
 >
 > 2. A consumer-grade wireless router that was plugged in and "just
 > worked" because it got an address from DHCP and then handed out
 > addresses on its own little network.
 >
 > These are at remote sites that are on their own subnets
 > (10.100.x.0/24; about 130 of them so far). Each site has a decent
 > Cisco router at the demarc that we control. The edge is relatively
 > low-quality managed layer 2 switches that we could turn off ports on
 > if we needed to, but we have to know where to look, first.
 >
 > I'm looking for innovative ideas on how to find such a rogue device,
 > ideally as soon as it is plugged in to the network. With situation #2
 > we may be able to detect NAT going on that should not be there.
 > Situation #1 is much more difficult, although I've seen some research
 > material on how frames that originate from 802.11 networks look
 > different from regular ethernet frames. Installation of an advanced
 > monitoring device at each site is not really practical, but we may be
 > able to run some software on a Windows PC in each office. One idea
 > put forth was checking for NTP traffic that was not going to our
 > authorized NTP server, but NTP isn't necessarily turned on by
 > default, especially on consumer-grade hardware.
 >
 > Any ideas?
 >
 > Thank you for your time,
 >
 > Jonathan Rogers
 >

Install your own Access Points for official use and have them scan for 
SSIDs in the vicinity.  Kills two birds.  One you now have official 
wireless access and your AP can detect rogue SSIDs.