Locate devices within a building
- by ams0
The situation:
Our company is spread between two floors in a building. Every employee has a laptop (macbook Air or MacbookPro) and an iPhone. We have static DHCP mappings and DNS resolution so every mobile gets a name like employeeiphone.example.com, every macbook air gets a employeelaptop.example.com and every macbook pro gets a employeelaptop.example.com on the Ethernet interface (the wifi gets a dynamic IP from a small range dedicated for the purpose). We know each and every MAC address of phones and laptops, since we do DHCP static mapping (ISC DHCP server runs on linux). At each floor we have a Netgear stack of two switches, connected via 10GB fiber to each other. No VLANs so far. At every floor there are 4 Airport Extreme making a single SSID network with WPA2 authentication.
The request:
Our CTO wants to know who is present at which floor.
My solution (so far):
Every switch contains an table listing MAC address and originating port. On each switch stack, all the MAC addresses coming from the other floor are listed as coming on port 48 (the fiber link). So I came up with:
1) Get the table from each switch via SNMP
2) Filter out the ones associated with port 48
3) Grep dhcpd.conf, removing all entries not *laptop and not *iphone
4) Match the two lists for each switch, output in JSON or XML
5) present the results on a dashboard for all to see
I wrote it in bash with a lot of awk and sed, it kinda works but I always have for some reason stale entries in the switch lookup tables, making it unreliable; some people may have put their laptop to sleep, their iphones drop connections after a while, if not woken up and so on..I searched left and right, we are prepared to spend a little on the project too (RFIDs?), does anybody do something similar? I can provide with the script if needed (although it's really specific to our switches and naming scheme). Thanks!
p.s. perhaps is this a question for stackoverflow? please move if it so.
