Since the first days of the web, users and administrators have sought to control the flow of information from the Internet to the local device. There are many different ways to implement internet filters, and numerous goals that organizations may want to achieve: Today’s post explores the last of these: blocking content based on category.Continue reading “Web Category Filtering”
Tag Archives: networking
Understanding SmartScreen and Network Protection
The vast majority of cyberthreats arrive via one of two related sources: That means that by combining network-level sensors and throttles with threat intelligence (about attacker sites), security software can block a huge percentage of threats. Protection Implementation On Windows systems, that source of network threat information is commonly called SmartScreen, and support for queryingContinue reading “Understanding SmartScreen and Network Protection”
Defensive Technology: Windows Filtering Platform
Last November, I wrote a post about the basics of security software. In that post, I laid out how security software is composed of sensors and throttles controlled by threat intelligence. In today’s post, we’ll look at the Windows Filtering Platform, a fundamental platform technology introduced in Windows Vista that provides the core sensor andContinue reading “Defensive Technology: Windows Filtering Platform”
Parallel Downloading
I’ve written about File Downloads quite a bit, and early this year, I delivered a full tech talk on the topic. From my very first days online (a local BBS via 14.4 modem, circa 1994), I spent decades longing for faster downloads. Nowadays, I have gigabit fiber at the house, so it’s basically never myContinue reading “Parallel Downloading”
ServiceWorkers vs. Network Filtering
In a recent post, I explored how the design of network security features impact the tradeoffs of the system. In that post, I noted that integrating a URL check directly into the browser provides the security check with the best context, because it allows the client to see the full URL being checked and ifContinue reading “ServiceWorkers vs. Network Filtering”
Web Weirdness: Probing Localhost
If you closely watch the Network tab in the Chromium Developer Tools when you try to log into Fidelity Investments, you might notice something that looks a bit weird. JavaScript on the page attempts to create WebSocket connections to a bunch of local ports on the IPv4 localhost address (127.0.0.1): So, what are those portsContinue reading “Web Weirdness: Probing Localhost”
The Challenge of IP Reputation
When protecting clients and servers against network-based threats, it’s tempting to consider the peer’s network address when deciding whether that peer is trustworthy. Unfortunately, while IP addresses can be a valuable signal, attempts to treat traffic as trustworthy or untrustworthy based on IP address alone can be very prone to mistakes. Background Most clients andContinue reading “The Challenge of IP Reputation”
Detecting When the User is Offline
Can you hear me now? In the web platform, simple tasks are often anything but. Properly detecting whether the user is online/offline has been one of the “Surprisingly hard problems in computing” since, well, forever. Web developers often ask one question (“Is this browser online?”) but when you dig into it, they’re really trying toContinue reading “Detecting When the User is Offline”
Captive Portals
When you join a public WiFi network, sometimes you’ll notice that you have to accept “Terms of Use” or provide a password or payment to use the network. Your browser opens or navigates to a page that shows the network’s legal terms or web log on form, you fill it out, and you’re on yourContinue reading “Captive Portals”
Chromium’s DNS Cache
Last Update: June 24, 2024 From the mailbag: Q: How long does Chromium cache hostnames? I know a user can clear the hostname cache using the Clear host cache button on about://net-internals/#dns, but how long it will take for the cache to be removed if no manual action is taken? After changing DNS records onContinue reading “Chromium’s DNS Cache”
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