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What is Packet Sniffing ?

Last Updated : 23 Mar, 2023
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When any data has to be transmitted over the computer network, it is broken down into smaller units at the sender’s node called data packets and reassembled at receiver’s node in original format. It is the smallest unit of communication over a computer network. It is also called a block, a segment, a datagram or a cell. The act of capturing data packet across the computer network is called packet sniffing. It is similar to as wire tapping to a telephone network. It is mostly used by crackers and hackers to collect information illegally about network. It is also used by ISPs, advertisers and governments. ISPs use packet sniffing to track all your activities such as:

  • who is receiver of your email
  • what is content of that email
  • what you download
  • sites you visit
  • what you looked on that website
  • downloads from a site
  • streaming events like video, audio, etc.

Advertising agencies or internet advertising agencies are paid according to:

  • number of ads shown by them.
  • number of clicks on their ads also called PPC (pay per click).

To achieve this target, these agencies use packet sniffing to inject advertisements into the flowing packets. Most of the time these ads contain malware
Government agencies use packet sniffing to:

  • ensure security of data over the network.
  • track an organisation’s unencrypted data.

Packet Sniffer – Packet sniffing is done by using tools called packet sniffer. It can be either filtered or unfiltered. Filtered is used when only specific data packets have to be captured and Unfiltered is used when all the packets have to be captured. WireShark, SmartSniff are examples of packet-sniffing tools. 

How to prevent packet sniffing –

  • Encrypting data you send or receive.
  • using trusted Wi-Fi networks.
  • Scanning your network for dangers or issues.


  • Network troubleshooting: Packet sniffing can be used to identify network problems by examining the packets and identifying issues such as network congestion, packet loss, or improper configuration.
  • Security analysis: Packet sniffing can be used to detect and analyze security threats, such as network intrusions, malware infections, or unauthorized access attempts.
  • Network optimization: Packet sniffing can be used to optimize network performance by identifying bottlenecks and optimizing the network configuration.
  • Protocol analysis: Packet sniffing can be used to analyze network protocols and identify areas where they can be improved or optimized.


  • Privacy violations: Packet sniffing can be used to intercept sensitive information, such as passwords, credit card numbers, or personal information, which can be used for malicious purposes.
  • Legal issues: In many jurisdictions, packet sniffing is illegal without the express consent of all parties involved in the communication.
  • Resource usage: Packet sniffing can consume a significant amount of system resources, especially if large amounts of network traffic are being analyzed.
  • Complexity: Packet sniffing can be a complex process, requiring specialized knowledge and tools to analyze network traffic effectively.

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