File extension .CAP
| Full Name | Developer | Category |
|---|---|---|
| PacketView Pro Packet Trace Data Format | N/A | Data Files |
A CAP file is a packet capture file, or network packet trace file, which contains captured data about activity on a network. It is created with the .CAP extension when using packet capture programs like Wireshark, Netwitness Investigator, WinPcap, and Microsoft Network Monitor, among others. CAP files are used to troubleshoot network performance issues and detect malicious activity on a network.
The CAP extension is related to the ERF/ERFX (Extensible Record Format) and PCAPNG (PCAP Next Generation) file formats, as well as the PCAP (Packet Capture) variant, which are all used in packet sniffing. Other network packet capture formats include TCPDUMP ( .DMP) and SNOOP ( .SNOOP) files. Typically, these files are read in raw binary form and stated with a text-based format of header lines.
Structure
A CAP file follows an organized structure, where each row represents a section of information about the individual packets being recorded. Within this structure, network protocol information is stored, such as source/destination address and port numbers (which may be seen in plain text if using Wireshark), type of protocol, length of packet data, and about 30 other fields of data.
Data Storage
A CAP file can be saved in the original ERF/PCAPNG/PCAP formats, as well as compressed versions, for example GZIP or BZIP2 formats. When choosing where to store the data it’s important to consider the size of the packets being recorded since large packets will cause the overall size to increase exponentially.
Programs for WINDOWS system
Programs for MAC system
Programs for LINUX system
After installing the required software, the operating system will usually automatically associate an unknown file type (in this case .CAP) with the new application. If this does not happen, we can help the system a bit by selecting the software for it, which it should always use to open files with the .CAP extension.
When choosing the software we can select the system to use this software every time.
Remember!
Using it for the first time it is good to check whether the .CAP file opened in the application can be read by us and opens in a way that allows us to use it. If everything is in order, select this option the next time you open a file with the .CAP extension. However, if the file has not opened correctly, we have to look for a different software, with which we can open files with the .CAP extension. Select a different software from our list and install it on your computer. After the software is installed, repeat inspection openings of a .CAP file. Sometimes you have to repeat the operation several times.
Other instructions
If none of the programs listed by us to work with the .CAP file has not meet your expectations, you can try searching other websites. But remember to avoid downloading programs "that can open any file". These applications not only have very limited functionality, but may also expose you to expense tens of dollars when purchasing a license.
In the vast majority of cases you will find the program dedicated to support the .CAP file, or any other file format. In addition, there is a chance that it will be a free program, and its functionality (concerning the .CAP file) will be extended to the maximum.
It is also good to check
- if the .CAP file has no errors
- or if it has been copied (or downloaded by the browser) thoroughly
Author’s guidelines
Mr B. Adam
Author of the guidelines / Founder of FileExtension.info
New technologies enthusiast, helping to solve problems with the files.
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