Shared computer suddenly appears in finder

[foz405]

I'm using Lion 10.7.5 and just this morning, a new computer has shown up in my finder sidebar called "Kim's Computer" . My internet connexion is via an Apple Airport Express to TP Link TD-8817 modem. I don't use any passwords to login, the only password set on the computer is the administrator password. Now, the woman who lives next door is called Kim, and she is about 100 feet away. She and her husband are not very friendly, so I haven't spoken to them.
1. Is it possible that they are connected to my wi-fi, or am I to theirs?
2. Although I have tried (by way of curiosity) to connect to this computer, it won't let me as I don't have the password. Can they connect to me ?
3. How can I make my connection more secure, without causing myself hassles with a multitude of passwords?
4. What is going on?
If anyone can help me with this, I would be most grateful.

PS: I have just gone in and added a password to my Airport Express and Kims Computer now seems to have vanished. Is this all I need to do to keep it secure? I'd also be interested in what was going on.

Grahame

 

[satcomer]

You should get into your main router and block her MAC address in it to stop her getting into your network.

 

[foz405]

You should get into your main router and block her MAC address in it to stop her getting into your network.

Now that she has vanished, I can't get her MAC Address (even if I knew how). Do I just need to be vigilant, or is adding a password to my airport express sufficient? It's all a bit of a worry. By the way, I never take the laptop out of the house, so I don't think external w-fi spots will be a problem, but even so, how do I secure myself?
Thanks

 

[nutjob]

Now that she has vanished, I can't get her MAC Address (even if I knew how). Do I just need to be vigilant, or is adding a password to my airport express sufficient? It's all a bit of a worry. By the way, I never take the laptop out of the house, so I don't think external w-fi spots will be a problem, but even so, how do I secure myself?
Thanks

A password is all you need, blocking the MAC address is unnecessary and pointless.

This is probably some random person who accidently connected to your network or maybe just wanted a little free internet. A password will stop those sorts of people. Anyone who is more determined than that can defeat a MAC address block trivially.

The fact that you have no had a password on your WiFi is not smart. You happen to notice this person, but anyone could have used your WiFi and done anything across your network, including hack other computers, illegally download copyrighted material or downloaded child pornography from the internet.

If you don't want to find yourself trying to explain to the authorities why these things are happening across your network, I'd make sure you always have a password on your WiFi (and everything else you own).

 

[foz405]

Thank you.
Eight years I've been running this computer/s on this network, and this is the first time I've noticed someone in the shared finder sidebar. Being old (and thus obviously stupid) is why I've never had a password on the network.
Grahame

 

[infantrytrophy]

Thank you.
Eight years I've been running this computer/s on this network, and this is the first time I've noticed someone in the shared finder sidebar. Being old (and thus obviously stupid) is why I've never had a password on the network.
Grahame

Grahame,

You might be old (I'll have to take your word for that ), but you are certainly not stupid! You know enough to access this forum to ask some good questions!

Despite the dubious name, I recommend that you take the advice of "nutjob" and place a password on your wifi network. Do this immediately! Anyone can access your open (non-password protected) network and do all sorts of things that you wouldn't want.

 

[foz405]

Done and thank you.