How can I find out what IP my router on my local area network is using?
In Terminal.app type
for more condensed output.
This is the fastest way as pointed out by Daniel. Thanks Dan.
There is another way that will take a lot longer:
The convention is to give the router the first address on the subnet. This means, in most cases, your router's IP address is the same as your IP address except it ends in 1.
If your IP is 10.0.0.105, then your router's IP is probably 10.0.0.1.
If you want the local address of the router it's most likely your gateway address. Press the Apple Menu () , got to 'System Preferences', then go to 'Network'. Select any of the items on the left (Ethernet/AirPort) that say connected.
On the right will be a bunch of fields, one of which is 'Router', which is usually 192.168.1.1.
If you want your internet IP address you can just go to http://www.whatsmyip.net/ and it will show you there.