This thread has piqued my curiosity on whether there'd be a way to detect a 
rogue access point, or proxy server with an inside and outside interface?  
Let's just say 802.1x is in place too to make it more interesting.  For 
example, could employee X, who doesn't want their department to be back billed 
for more switch ports, go and get some reasonable wifi router, throw DD-WRT on 
it, and set up 802.1x client auth to the physical network using their 
credentials?  They then let their staff wifi into it and the traffic is NAT'd.  
I'm sure anyone in a university setting has encountered this.  Obviously policy 
can forbid, but any way to detect it other than seeing traffic patterns on a 
port not match historical once the other users have been combined onto it, or 
those other users' ports go down?

David
 

On 6/7/18, 10:18 AM, "NANOG on behalf of Mel Beckman" <nanog-boun...@nanog.org 
on behalf of m...@beckman.org> wrote:

    When we do NIST-CSF audits, we run an SNMP NMS called Intermapper, which 
has a Layer-2 collection feature that identifies the number and MACs of devices 
on any given switch port. We export this list and cull out all the known 
managed switch links. Anything remaining that has more than one MAC per port is 
a potential violation that we can readily inspect. It’s not perfect, because an 
unmanaged switch might only have one device connected, in which case it wont be 
detected. You can also get false positives from hosts running virtualization, 
if the v-kernel generates synthetic MAC addresses. But it’s amazing how many 
times we find unmanaged switches squirreled away under desks or in ceilings.
    
     -mel 
    
    > On Jun 7, 2018, at 4:54 AM, Jason Hellenthal <jhellent...@dataix.net> 
wrote:
    > 
    > As someone already stated the obvious answers, the slightly more 
difficult route to be getting a count of allowed devices and MAC addresses, 
then moving forward with something like ansible to poll the count of MAC’s on 
any given port ... of number higher than what’s allowed, suspend the port and 
send a notification to the appropriate parties.
    > 
    > 
    > All in all though sounds like a really brash thing to do to your network 
team and will generally know and have a very good reason for doing so... but 
not all situations are created equally so good luck.
    > 
    > 
    > -- 
    > 
    > The fact that there's a highway to Hell but only a stairway to Heaven 
says a lot about anticipated traffic volume.
    > 
    >> On Jun 7, 2018, at 03:57, segs <michaelolusegunru...@gmail.com> wrote:
    >> 
    >> Hello All,
    >> 
    >> Please I have a very interesting scenario that I am on the lookout for a
    >> solution for, We have instances where the network team of my company 
bypass
    >> controls and processes when adding new switches to the network.
    >> 
    >> The right parameters that are required to be configured on the switches
    >> inorder for the NAC solution deployed to have full visibility into end
    >> points that connects to such switches are not usually configured.
    >> 
    >> This poses a problem for the security team as they dont have visibility
    >> into such devices that connect to such switches on the NAC solution, the
    >> network guys usually connect the new switches to the trunk port and they
    >> have access to all VLANs.
    >> 
    >> Is there a solution that can detect new or unmanaged switches on the
    >> network, and block such devices or if there is a solution that block 
users
    >> that connect to unmanaged switches on the network even if those users 
have
    >> domain PCs.
    >> 
    >> Anticipating your speedy response.
    >> 
    >> Thank You!
    

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