[ubuntu-uk] Find a Router's IP address

[Hakan Koseoglu]

On 19/10/10 16:54, Cornelius Mostert wrote:
> The scenario is as follow:
> 1. You have permission to work as Admin on a Lan
> 2. You do NOT have any documentation from the previous Admin
> 3. You find a router / WiFi Router that is in use and therefore you can
> NOT reset it
> 4. This router is a "home" / consumer router like Netgear, Linksys, etc.
> So not an enterprise router
> 5. You need to brows to the routers config web page to make some changes
> (you assume the default admin and password for the router) BUT you do
> NOT know the IP address
> 6. You know the router is NOT a DHCP server
>
> Now the question is HOW do you find the IP address of the router ???

If it is the router providing the access outside, netstat -nr will show 
you the route, hence the IP address of the router.
If you know which servers/clients are using it as a gateway, run those 
commands from there.

But what then, what will knowing the IP address provide to you, I'm not 
sure.

If the previous admin has walked away with all of the information, I'd 
treat that router as compromised and take it off the net ASAP and 
replace it with a known configuration - damn the users, just let them 
know about the outage.

Nmap will attempt to show you any IP addresses on the network with a 
reasonable distinction of if the device is Netgear, Cisco etc.