The situation on Linux is a bit different – instead of a service the user needs to be allowed to access the network card for capture tasks. The “sc” command is also used to “stop” or “start” the NPF service, but you need an administrative (“elevated”) command prompt to do that. (STOPPABLE, NOT_PAUSABLE, IGNORES_SHUTDOWN) Instead, you can check it using the “sc.exe” utility with the “query” command on a command prompt: sc query npf If you want to check the status of the NPF service, you won’t find it in the services list of Windows. Wireshark (well, dumpcap, to be more specific) accesses the driver (called “NPF”), allowing packet captures even if Wireshark itself runs with normal user credentials that wouldn’t be good enough to do the same without NPF. Wireshark (and most likely any other network analysis tool) on Windows solves the problem by creating a special capture service running with enough authorization to access available network cards. Some companies even have a security rule that users aren’t allowed to run packet capture software on their laptops or PCs. The problem is that capturing packets is considered a security risk, as it may allow access to data the user shouldn’t have or isn’t allowed to have. This is something Windows users of Wireshark might wonder what the fuss is all about, while Linux users often encounter the frustrating situation of not being able to capture any packets unless they run Wireshark as root. Destination MAC filters and “Promiscuous Mode”.
Let’s take a look at the basic things you need to consider when capturing packets from Ethernet (we’ll look at WiFi captures later):
It’s relatively easy to capture packets with a PC or Mac using a built-in network card, but getting exactly what you need may be a bit more difficult or even turn into a real challenge. So when we’re talking about using a standard network card like they are built into most PCs and laptops these days, the answer to the question of “is it good enough to capture packets?” is – you probably guessed it already: “it depends”.Ĭapturing packets is one of those disciplines that are best described as “easy to learn, hard to master”. This may sound unsatisfactory at first, but the problem with a lot of questions regarding network analysis (and packet capture) is that there are always so many things to consider. One of the most common answers that come to my mind when being asked questions during or after a talk at a conference is the famous phrase “it depends…”.
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