macbook says unknown ip address

Hope someone can help please!

I have a macbook I bought in 2009. I am happy to share more details, but pretty much the problem is I need to find my IP address and my macbook says it is unknown. I went to the terminal and entered "ifconfig" (which worked for my roomate) but my ip address wasn't listed. In searching for it, somewhere it said that my ip address was "unknown." What do I do?? How can I find it?

THANK YOU!

System preferences > Network >Advanced >TCP/IP

Thank you for a quick response. Unfortunately I think it is more complicated than that. Although my computer knowledge is embarassingly limited I did know that is where the information is supposed to be found, however currently on my computer those fields are blank. I looked everywhere I could think of to find it, and at some point in my search¨it said "ip address unknown" but of course I cannot remember where that was.

To give a little more detail, my friend and I just moved into a new apartment in Spain and we are trying to connect to the wireless. We both have macbooks. Apparently the landlord in the apartment next door has wireless, but when we try to connect with the password it says connection failed. Our roomate says that others who have lived in the apartment had to enter their IP addresses into the landlords computer. Its really a bit of the blind leading the blind over here, I have never heard of anything like that but that doesnt mean much. We found my friends IP address for her macbook, but as I said, mine is no where to be found. Please help!!!

What is your room mates IP address, it should be something like 192.168.0.22 or similar

If you are not yet connected to your landlord's wi-fi, your macbook will not have an IP address.

IP addresses are assigned by the router (in a DHCP setup, which is 99% of home wi-fi configurations), which you obviously will not have yet if you are not connected.

If you need to enter your computer's address into your landlord's router, what you are probably looking for is the MAC address of your NIC. This will be a series of letters and number separated by colons (i.e.: XX:XX:XX:XX:XX:XX) and can be found by going to Applications > Utilities > Network Utility and selecting the desired network interface from the drop down (for wi-fi you will want "Wi-Fi" - en1).

This is a typical setup that some people use for "security" in their home wi-fi setups. Basically it only lets a pre-determined list of MAC addresses access the network. MAC addresses can be spoofed in about 2 seconds, so this is actually very insecure. A better way of securing the network is through WPA encryption, but I doubt you are going to change your landlord's mind about that.

Anyway, I hope this helps, or at least sets you in the right direction.