Who is your computer talking to? Your browser isn't the only application that's sending data online. Your word processor might be phoning home; a file undelete utility might be talking to its mother ship, and even Windows' own services may surprise you. These are not necessarily nefarious actions, but they're worth knowing about. GlassWire is a free and beautiful utility that lays all of this bare.
One of the most important things about GlassWire is that it's beautiful. This isn't a minor detail: For many users, network security is equal parts daunting and tedious. Having a tool that's just fun to pop open and watch throughout your day makes a big difference. The graph scrolls in real-time, and there's a zoom slider across the bottom of the window letting you check out longer periods of time at a glance.
When you see traffic suddenly spiking, you can easily drill in and find out exactly which application(s) on your computer caused that spike, and which Internet hosts they were communicating with. The graph also makes it easy to tell apart outbound traffic (uploads, shown in yellow) and inbound traffic (downloads, shown in pink).
To get a bigger sense of what your network traffic looks like, you can zoom the graph out to show three hours, 24 hours, or an entire week's worth of network activity. There's no lag when you do this: All filtering operations are instant.
The graph then lets you filter activity out by application. For instance, what does Rdio's network traffic look like? How much data does it download over a day of listening, and does it use the network constantly or in brief spurts? GlassWire makes this both easy and fun to determine.
Next, you can filter network activity by protocol. This can reveal some surprising information in itself. For example, I use a webmail client: I don't have a traditional email client such as Outlook, so I did not expect to see any SMTP activity on my computer. GlassWire reminded me one of my applications does send data to the Internet over SMTP--and it's not an email client.
Because it gives you such a wealth of information, it only makes sense for GlassWire to also let you do something with your newfound knowledge. That's where the built-in firewall comes in. The Firewall tab lets you review the list of all apps communicating, each with its own miniature traffic chart. It also lists which network hosts each app communicated with--and a single click will muzzle that app for good. If you already use a firewall you're happy with, you can disable GlassWire's built-in firewall from this same tab without having to dig through a Settings dialog.
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