Packet Sniffing: An Informative Guide (2021)

Ajay Ohri


For many years, people in the world of cyber networks and traditional computing were confused about what is packet sniffing, and they had questions about the role played by sniffer in the industry. Indeed, packet sniffing has a history that dates back to the early 1990s. Since then, hackers have found a way of learning more about conversations that happen in the network by reading packets over a while. This phenomenon is known as packet sniffing. And, the attacks have many sophisticated strategies and exquisite packet sniffing software to rely upon. 

In this article let us look at:

  1. Packet Sniffing Definition
  2. How is Packet Sniffing done?
  3. How do Hackers use Packet Sniffers?
  4. Prevention

Packet Sniffing Definition

Now would be the best time to define packet sniffing. By definition, packet sniffing is the process of collecting data packets that are sent across the network. It does not depend on the host or target packet addresses. Instead, it focuses on retrieving data from the conversation. Most of the time, packets consist of a subset of many more packets. All of these packets translate into crucial pieces of information for the sniffer. Packet sniffing is also carried out by network administrators. They sniff data packets to learn more about the traffic from their private and secured network channels. 

On the other hand, cybercriminals rely on packet sniffing technology to host attacks. During these attacks, they extract a variety of information. The most common use cases for packet sniffing would be to snatch sensitive pieces of data from the network. This could be anything like the victim’s credit card information, social security number, or even their bank account credentials. Sometimes, sniffers rely on this technology to learn more about the kind of data a user focuses on. This helps the sniffer realize more about their surfing patterns and even their interests. 

How is Packet Sniffing done?

So, how does packet sniffing work? Theoretically, the methods used for sniffing packets are the same for both genuine and criminals use cases. The kind of tools and techniques used are also consistent. This is why cyber specialists spend lots of time mastering the act of sniffing. 

The network is a collection of nodes that represent different devices. During the transfer of data, packets are sent from one node to another. The connection established between two nodes can be physical or even wireless. Not all nodes travel in the same line. Instead, they are broken down into smaller packets and each packet can choose a different path to reach its destination. This means the packets carry a payload and header information about their intended destination. In a de-facto condition, packets that don’t carry the right node address will be rejected. 

When it comes to packet sniffing attacks, the above logic is broken. Instead, the verification of packets and their target address is omitted. This allows the packet sniffing hardware and software to collect packets that are reaching the “sniffers nodes”. Irrespective of the address mentioned in the packet header, the sniffing tool would collect and analyze it. 

How do Hackers use Packet Sniffers?

As mentioned previously, packet sniffing tools play a crucial role in this operation. Network administrators study these tools to understand how to detect packet sniffing.

Packet sniffing hardware comprises a special device that can be connected to the network. These are carefully designed devices that collect packets from a hop. Often, hackers use packet sniffing hardware in chosen network segments. This is where they anticipate a certain kind of traffic flow. The hardware ensures that no piece of data is lost in the chosen flow too. Once the required data is collected, it would be stored in a temporary memory space or sent to another machine in the network. The ultimate move depends on how the sniffer has configured the hardware.

On the other hand, there is special packet sniffing software to accomplish this operation too. This piece of software works by altering the network configuration. It ensures that all the traffic in the network is pushed up the stack. When it comes to network adaptors, this kind of configuration is also known as a “Promiscuous Mode”. Once the network enters into this mode, the only job of the sniffer is to collect, analyze, and separate the traffic. The software sniffer relies on the network interface for completing its operations. 


To begin with, organizations and individuals who work with sensitive data must make use of a VPN service. The VPN will ensure that the data is encrypted during the transfer. Also, the IP address of the host or target is hidden during the transfer. This makes the entire transaction extremely safe and secure. Moreover, there are many impressive tools and platforms for creating safe and secure VPN connections. 

Two, you should never connect to unreliable public WiF

i networks. This increases the chances of network sniffing attacks. Hackers often create networks that can mimic genuine public WiFi services. By connecting to one a fake WiFi network, you will risk the chances of sending confidential information. Any traffic that is sent or received via the network will be monitored. 

Over the years, most websites have migrated to HTTPS. This is a secure transport layer protocol that ensures the safety and authenticity of the data sent in the network. The HTTPS protocols make sure that data is only received by the intended target. Also, it stops hackers from sniffing crucial pieces of data from the network. Even though HTTPS doesn’t encrypt everything, it proves to be useful when paired with virtual private networks. 

Finally, users need to be extremely careful when you receive links and messages from unknown sources. Always verify the email address of the sender. Most of the time, the address will be altered to “appear” like a genuine person or organization. 


Packet sniffing attacks happen daily. Now and then, sniffers are using their hardware and network configuration tools to sniff data from networks. The best way to handle these attacks and avoid them is by using a private network that is both safe and secure. Also, you need to make use of protocols that have “security” as a part of its game plan. It

So, have you made up your mind to make a career in Cyber Security? Visit our Master Certificate in Cyber Security (Red Team) for further help. It is the first program in offensive technologies in India and allows learners to practice in a real-time simulated ecosystem, that will give you an edge in this competitive world.

Also, Read

Sniffing: A Beginners Guide In 4 Important Points

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