What is PCAP app?

What software is used to collect PCAP data?

I want to use Wireshark to save pcap data while running a program in QEMU.

Are there any problems with recording at the kernel level? I was able to record using the command line in terminal (as sudo), but was unable to capture during the program's execution in QEMU.

You can use pcaprecv() if you run your program as root or have elevated privileges. For example, if you have something like this #include #include void main(). In the root account, you will probably get different results depending on if you are capturing packets that are transmitted from your interface and packets that are received by the interface. If your program is running with user privileges, you should not have any problems. As long as you are not writing anything other than packets that go through the network device, you should be fine.

How do I open a PCAP file?

A capture file produced by tcpdump or Wireshark is just a PCAP file, so how does one open the file?

Do you simply double-click on it and your tool opens it? tcpdump -i eth0 host 192.168.12

If this is the case, then why do you need to install additional software if everything is already installed on your computer? The program that you are using is already installed (tcpdump is part of tcpdump-utils, as mentioned in the answer to Is there anything I must have installed if I want to analyse packet captured in a pcap file?). The shell will exit, the window that was opened by the shell will disappear and your pcap capture will be loaded. If you want to have that "load" happen faster, you can also start tcpdump (or another capture utility) with the -r parameter, telling it to load automatically when the capture is done, so that after loading your pcap capture, tcpdump will start capturing traffic.

How does PCAPdroid work?

The name "PCAPdroid" was invented to refer to a certain type of device that used to be popular in the 1990's, but which are now all but extinct.

Before we get into details, it's probably useful to mention that the word "Pcap" is short for Packet Capture. Pcap is the term used to refer to a certain type of technology, but many modern network devices such as switches, firewalls and even WiFi access points have built-in packet capture functionality.

It's therefore not uncommon to find a network device that has both a Pcap interface (like most firewalls do) and a serial interface (like most routers do). These devices are called "dumb" because they don't understand protocols such as IP, TCP, UDP, ICMP or anything else. The "dumb" devices just receive data and pass it along to the applications running on the computer that is connected to the device.

The "smart" devices are the ones that understand the protocols. Some of the "smart" devices can be connected to a PC with a serial or parallel port, but these devices are rare because it's not easy to connect a computer to an embedded device. Most of the time, the devices use USB ports. Some devices come with a serial/parallel converter, while others (like the Linksys WRT series routers) come with a dedicated USB to serial converter.

PCAPdroid works with these devices. It creates a virtual serial device that allows a standard serial port to communicate with the device as if it were a serial device on your computer. The device reports what the PCAPdroid is capturing with data about the frames captured, and the PCAPdroid can report the packets captured as well.

The PCAPdroid is also compatible with some devices that use Pcap technology directly. This includes devices like the TP-Link devices.

There are two parts to PCAPdroid. One part (the "driver") sits on top of the Linux kernel, and the other part (the "application") runs on the computer and communicates with the device using the driver.

The driver runs in the Linux kernel, and provides a "virtual" serial port to the applications running on the computer. The driver talks to the device using a very simple protocol.