Is my computer safe when it’s asleep?

Q: Does putting the computer to sleep disconnect it from the Internet and while in sleep mode is it affected by “Wake on Lan?”

This can get a little complicated and technical, but I’ll try to explain the basics as simply as I can.

The answer to this question varies greatly depending upon the exact equipment and operating system you are using.

In general, when a computer goes to sleep, only essential items continue to run in a low-energy consumption mode.
Things like the network connection are shut down, making it inactive and technically “not connected” to the Internet, even though you are still physically connected to the Internet.

This technically provides the potential for a remote connection, even though your computer is in sleep mode.
Many computers and network devices have an option to “Wake on Lan” (WoL) or “Wake on Wireless Lan” (WoWLAN) which makes your computer accessible while in sleep mode.
Not only can your computer be woken up from sleep mode with WoL turned on, but properly configured, it can actually be turned on even if it’s been shut down through the use of a “wake-up packet.”

Wake-up packets (a.k.a. magic packets) are designed to allow authorized remote users to activate off-line computers with a specially encoded packet from the Internet.

If this is all news to you and you’re a general home or small business user without an IT department, it’s highly unlikely that you have this rather elaborate setup configured on your computer and network.

If your computer is part of a business network and managed by an IT group, it’s certainly possible that they’ve set your system up for this type of remote activation, so check with them to confirm.

Even if WoL is turned on and someone steals the information necessary to send you a properly formatted magic packet, it doesn’t mean they have total access to your computer. At best, they can annoy or freak you out by remotely turning your computer on, but without other exploits in place, that’s about it.

Frankly, if a stranger has the ability to turn your computer on because you have WoL turned on, you have much a bigger problem because they would have had to gain administrative access to your router/firewall or other security settings to pull it off.

You can track down the specific steps to turn off the WoL in your computer’s BIOS or your network interface settings, but I don’t really see the need as it’s not really a security issue on its own.

If your computer is seeming to wake up on its own, it’s more likely to be one of your connected peripherals. Lots of devices, such as your mouse and keyboard, are designed to wake up your computer when you start to use them, but some printers, scanners and lots of USB-connected devices might also be configured to wake up your computer upon use.

A quick way to see the last device to wake up your computer is through a Windows command line.

In Windows 7, click the Start button and type “cmd” into the Search box to launch a black command line window.

In Windows 8, hold down the Windows logo key + X and click the Command Prompt option.

Type powercfg -lastwake to identify the event or device that caused the last waking process.

To see all devices capable of waking up your computer, type powercfg -devicequery wake_armed so you’ll know what devices to troubleshoot.