Someone has my IP address

Whenever you communicate with someone else, they have your IP address. How do you think that, say, the Apple site could send the contents of this Web page to you, if it didn't know where to send it?

Typically:

• Your Mac or PC has a local IP address that isn't globally unique and isn't known to anyone on the wide-area side of your router.
• Your router has a globally-unique IP address assigned by your ISP.
• When you visit a Web site, your router takes the packets from your computer and forwards copies of those packets that have its own IP address as the return address.
• When the Web site replies to you, it uses the IP address of your router that it found in the source IP address fields of your packets as the destination IP address for its reply packets.
• Your router then forwards the packets to your Mac or PC, with your computer's non-unique local IP address (rather than the router's globally-unique IP address) as the destination IP address.

That's the basic idea. There could be a lot of communication on the Web site, between multiple machines that work together to reply to your browsing requests. But it's trivial for any of those computers – or for that matter, any part of the Internet that forwards packets between your router and the Web site (or vice versa) to observe, and store, copies of your router's IP address.

Just like if you send Postal mail to the I.R.S, with your return address clearly visible on the envelope. Anybody who handles that piece of mail could observe and copy your home address. Only in the Post Office example, there are probably more laws or Post Office policies prohibiting random people from doing so …

In what context did you learn of this "Security breach"?

Did someone who you didn't know – possibly claiming to be Apple, Microsoft, etc. technical support, or from an antivirus company - call you up on the phone to urge you to take action to fix it?

Don't bite. It's a scam.

Same thing if you get e-mails from someone you don't know, trying to panic you by saying that your computer is infested with a hundred viruses, or that your subscription to some antivirus product you don't use has expired.

Don't bite. It's a scam.

It's a scam. Ignore it and rethink accessing that site for at least a while.