How do I make sure my Macbook is secure?

I'm still new to Apple security, and what needs to be done to protect the computer. I think i'm having some issues that I need some input on. I was under the impression that Macs are pretty secure, but i'm having some alarming issues.

A few weeks ago, I noticed THIS when I took a look at my network status:



In the list of open ports, it looked like the Ethernet port was being exploited somehow. I deleted it, and it hasn't been back since. Then, a week later, I open up the "Network status" pane and a window pops up that says "Another application has changed your network settings".

I did an erase and install of OSX. My firewall is on, I don't have any types of sharing enabled, my router's firewall is on. I'm using WPA. I changed my login password and WPA pass as well.

Now, when I click the lock in the preferences pane, it will automatically be unlocked after I restart the computer, or at random times. I fear there's still open security issues with the computer.

Can anyone give me some pointers as to how to make my computer more secure?

I don't know if this link is any help or not but the problem may be with your ISP and Airport rather than any security issue.

Apple - Support - Discussions - Airport Express and Comcast High Speed ...

A quick google brings up lots of threads concerning Airport and Comcast.

The best security for wifi doesn't come from using a key.

The best wifi security comes from locking down your router BY MAC ADDRESS. Using a key too is fine. This way even if they crack a key their computers mac address will not be allowed to access the network.

Operate as a limited user once your preferences are set up. Tell your firewall to block all traffic except for what you add to the "allow" list. Password-allow all setting changes and events. Don't allow sharing of files. Make sure your logging is activated in your firewall preferences, and keep an eye on those logs for a while. Shut down your mac when not in use.

Usually, there are lots of precautions you have to take to secure your networks, on any computers. But when it comes to software, Macs are excellent.

Let me correct my previous post. After playing with various programs / methods for cracking wifi (only on my own network) I have quite a different view.

Mac addresses can be spoofed (faked) so they are actually pretty much useless against a skilled hacker. WEP can be cracked in under 10 minutes usually.

WPA is the best method, but only if you use a strong password. Use a 30 digit passkey with a mixture of lower and upper case letters and numbers, and make it a random mixture. Nobody will ever crack it. The common mistake is to use a common word for the passkey, and this can be cracked with some effort.

So again, WPA and a strong passkey, and you are good to go.

And when you use a passkey, all communication is encrypted while the MAC-address restriction is only about connecting to the network and does not do anything about the ongoing communication within the network. Seems the best way is to use both.....

I think WPA has started being cracked, according to slashdot. WPA2 is still fully uncrackble atm, though.