Network

This article shows a simple solution to a weird networking problem that plagued me for hours: IPv6 packets were sometimes lost; IPv4 was not affected. Problem: IPv6 Ping Timeouts and Packet Losses Symptom: Teams Issues I noticed the problem first when there were intermittent connectivity issues in Teams during a meeting.

I had a weird issue on my laptop: whenever I connected to our company’s VPN, I lost local internet connectivity. As it turned out, this was caused by incorrect network interface priority metric settings. To spare you and my future self many frustrating hours of troubleshooting, here’s what caused it.

This post lists the internet communication targets of Adobe Acrobat Reader, Photoshop, and Creative Cloud. This post is a part of my application network connection monitoring series, a group of articles that explain how to analyze the network traffic of any Windows or macOS app.

This post lists the internet communication targets of Citrix Virtual Apps and Desktops (formerly XenApp/XenDesktop). This post is a part of my application network connection monitoring series, a group of articles that explain how to analyze the network traffic of any Windows or macOS app.

This post lists the internet communication targets of the Microsoft Windows operating system, including its various services and UWP apps. This post is a part of my application network connection monitoring series, a group of articles that explain how to analyze the network traffic of any Windows or macOS app.

This post lists the internet communication targets of Microsoft Office and Teams. It is a part of my application network connection monitoring series, a group of articles that explain how to analyze the network traffic of any Windows or macOS app.

This is part 1 of my application network connection monitoring series, a group of articles that explain how to analyze the network traffic of any Windows or macOS app. The communication targets of the Windows OS and of many popular apps are listed in dedicated posts.

The most important change in version 2.0 of uberAgent is the new architecture. In addition to that we have made many other improvements, significantly reducing the agent’s footprint while increasing the quality of the collected data.

You have been there: end-users are complaining and your boss demands an explanation why “Citrix is slow” - again. You, the XenApp/XenDesktop admin, desperately look at Task Manager and Perfmon, but you cannot find a thing. Your servers are humming along quite nicely, but still: applications are slow, the system feels sluggish and logons are taking forever. And then, all of a sudden, things are back to normal. What was going on? How do you prevent that from happening again?

With the advent of BYO it has become fashionable to regard PCs as untrusted devices that should be isolated in a dedicated security zone. Zoning Such an approach has a big advantage: by separating clients from servers it is possible to treat them differently and potentially apply more relaxed security policies - which is a basic requirement for BYO. In a truly BYO-only environment you block everything except Citrix ICA or some other remoting procotol of choice at the firewall and life is good. In real corporate networks things are a bit more complicated, however. Say you want to isolate your managed Windows PCs. In that case you might want to be able to manage them remotely from systems outside the client security zone (e.g. from management terminal servers). And suddenly you have a problem: Windows management protocols, especially RPC and DCOM, are not exactly firewall-friendly.

Windows 7 comes with several features that promise to greatly improve file access over a WAN. One of them is version 2 of the SMB protocol, another transparent caching. This article describes how I measured their effectiveness.

In its issue 1/2012 German c’t magazine published an article about security in Wi-Fi networks. The authors describe how very easy it is to gain access to other people’s accounts and passwords in a world where travelers happily connect to any wireless network they can get hold of. This is a short summary of the original article, intended to highlight the dangers.

Under certain circumstances, you cannot connect to administrative shares (e.g. C$) on remote computers, even though you use the right credentials. Accessing a normal (i.e. non-administrative) share works flawlessly, though.

Sometimes the “Sharing” tab in the folder properties goes missing. If that is the case and you right-click a folder and select “Properties”, it looks like this: Missing-sharing-tabThis is what is should look like:

I had an interesting little case to solve at home recently when my headless file server suddenly would not accept RDP connections any more. It still worked flawlessly as a file server, so I ignored the problem for a while.