By Hayden Duplantier, TraceSecurity
Before we learn packet sniffing, we have to understand what a packet is. A packet is a small unit of data transmitted across a network. The computer or device that receives it then sends packets over the network and recombines them. A packet has three parts: header, payload/data, and trailer. 
Packets and packet sniffing are part of the Data Link Layer in the OSI (Open Systems Interconnection) model and are associated with networks. Packet Sniffing is a method of detecting and accessing packet data sent through IP/TCP (Internet Protocol/Transmission Control Protocol), which are communication protocols used to interconnect network devices on the Internet.
How Does It Work?
Packet sniffers or packet analyzers are hardware or software that monitor network traffic. There are two types of packet sniffing: hardware packet sniffing and software packet sniffing.
Hardware packet sniffing uses a device that is plugged directly into a network. This device creates a connection point between your computer and the network, allowing access to specific parts of the network.
Software packet sniffing uses a program to capture traffic on the network and is more popular today.
Another way to analyze packets is to filter them. Unfiltered packet sniffing allows data packets to be captured and analyzed later, while filtered packet sniffing allows data packets to be captured only if they meet specific criteria.
Packet Sniffing Attacks
A packet sniffing attack occurs when a hacker uses a packet sniffer to obtain personal and confidential data for malicious purposes. This allows hackers to launch more attacks, such as spoofing, SQL injection, and malware.
Passive sniffing occurs when several devices are connected to a wireless network, and a hacker is also connected and passively monitors traffic. This type of packet sniffing is difficult to detect.
Active sniffing is used on switched networks, where the packet’s destination can receive the data. Hackers add traffic to the network to get around this.
Types of Packet Sniffing Attacks
Browser sniffing attacks are when hackers use your saved usernames and passwords to websites, allowing access to your accounts.
Password sniffing attacks involve hackers using packet sniffers to capture packets of unencrypted password data while they are being transported to their destination.
Session hijacking is a method of packet sniffing that allows a hacker to obtain your session ID and authorize malicious activities on the network.
Knowing methods of attacks can help you understand what procedures you need to put in place to protect yourself. Hackers use many methods, like packet sniffing, to steal your data or information. The more you know about these methods, the more you can protect yourself from these malicious actors.
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