How to find the DHCP assigned address of a new device
Most devices that can talk TCP/IP have screens attached to them. I was setting up a IP->Serial device by quatech and it conveniently uses DHCP. It turned on and got link, but what's its IP ?
Most devices with an Ethernet interface will have the MAC address written somewhere on the outside of the device. Find the mac address and you're half way there.
MAC addresses are 6 sets of numbers. The first 3 sets are assigned uniquely to a manufacturer and the last 3 are for that manufacturer to distribute.
- A MAC address is always unique, an IP is not.
- A MAC address does not change for an interface, an IP can.
I found the MAC address of my device on the case: 00:0b:28:00:1d:8d
Now I ping the broadcast of my subnet:
eg. ping -c 1 192.168.2.255
And finally I check my now populated ARP cache:
eg. arp -an | grep -i 00:0b:28:00:1d:8d
Yielding:
? (192.168.2.224) at 00:0b:28:00:1d:8d on fxp0 [ethernet]
You can always look up MAC addresses and vendors here:
http://coffer.com/mac_find/