I have an IP address of a computer which I am currently away from, and I need the MAC address. How do I get the MAC address if I ony have the IP?
In short the answer will be you can't.
It is usually not possible for a person to get the MAC address of a computer from its IP address alone. These two addresses originate from different sources. Simply stated, a computer's own hardware configuration determines its MAC address while the configuration of the network it is connected to determines its IP address.
However, computers connected to the same TCP/IP local network can determine each other's MAC addresses. The technology called ARP - Address Resolution Protocol included with TCP/IP makes it possible. Using ARP, each computer maintains a list of both IP and MAC addresses for each device it has recently communicated with.
If you are on the same network you can open up a Terminal:
hit Ctrl-C on the keyboard to stop pinging then do a:
a list should appear, look for the ip you just pinged and next to it is the MAC address of the device.