The number of available IPv4 addresses is technically finite and cannot be fully answered. According to the American Registry for Internet Numbers (ARIN), the Regional Internet Registry (RIR) for North America, the IPv4 free pool reached its final /8 on September 24, 2015 and has been depleted since then.

At the time of this writing, IPv4 address space is still available through certain transfers and other mechanisms, such as IPv4 leasing, but it is expected to run out in the near future.

To unhide a hidden WiFi network on Windows, go to the Network and Sharing Center in Control Panel. Click “Manage Wireless Networks” from the left pane. Click “Show Hidden Networks” from the top bar. Select the network and click “Connect”.

For Mac OS, go to System Preferences > Network > Wi–Fi. Select the Advanced button at the bottom right corner of the window. Select the “Wi–Fi” menu and check “Show Wi–Fi status in menu bar”. Select the hidden network and click “Connect”.

On iOS devices, go to Settings > Wi–Fi. Tap the “i” icon next to the hidden network name. Enter the password for the network and toggle the “Connect On Demand“ switch to On (if available).

If you have received a blackmail email, it is important to take action. You should contact your local law enforcement agency and report the email. Depending on the threat and where you live, the local police or the FBI may be responsible for investigating extortion and blackmail cases. Describe the email in detail and provide copies of all emails related to the blackmail threat. Be sure to also send any details such as the sender‘s email address, the email header information, and other identifying information. Additionally, if you have been asked to pay or have already sent money, report that to the authorities. It is important to take precautionary measures in an effort to preserve any evidence and stop the person from continuing this type of criminal activity.