What is Network Sniffing? Types, Working, Usage, Tools

Sniffing is the technique used to monitor and record all data packets continuously that go through a network. Network/system administrators employ sniffers to monitor and troubleshoot network traffic. Attackers use sniffers to capture data packets carrying sensitive passwords and account information. Sniffers are implemented as hardware or software in the system. A hostile intruder can gather and analyse all network traffic by using a packet sniffer in promiscuous mode on a network.

A packet sniffer is another term for a network sniffer. Because every packet of data is sniffed through the network to avoid network-related issues, it's called a packet sniffer. The packet sniffer tool is implemented to investigate cybercrime, hackers, and data theft. It can be employed for both ethical and unethical reasons.

Network Sniffing can be either Active or Passive.

Active Sniffing

Active Sniffing involves sniffing in the switch. A switch is a network device that provides a connection between two points. The switch controls the flow of data between its ports by continuously checking the MAC address on each port, ensuring that data is sent to the correct destination. Sniffers actively spike traffic into the LAN to monitor communication between targets and enable traffic sniffing. Active sniffing is done in a variety of ways.

Passive Sniffing

The attacker does not interact with the target in this sniffing. They connect to the network and collect packets sent and received by the network and the packets sent and received between two devices. This sniffing is done through the hub. An attacker uses their PC to connect to the hub. The attacker only needs a LAN account.

Types of Network Sniffers

Following are the different types of Network Sniffers −

  • Mac sniffers − Sniffers are used to sniff data relevant to the MAC address filter.

  • Protocol sniffer − It sniffs the data on the network for network protocols.

  • LAN sniffer − This type of device is primarily employed in internal systems or networks, and it can inspect an entire range of IP addresses.

  • IP sniffers − Sniff all data relevant to a specific IP filter. It records the data packets for analysis and diagnosis. IP sniffers capture network traffic and log the information, generally delivered in a human-readable format for analysis. They may be used by network administrators and hackers of all stripes to assess the current condition of a network, identify network vulnerabilities, and evaluate network performance.

  • ARP sniffers − Rather than sending packets to the host only and passed to the network administrator, packets are sent to the ARP caches of both network hosts in this sniffing. It also allows attackers to map IP addresses to MAC addresses, carrying out packet spoofing and other vulnerabilities or poisoning attacks.

  • Password sniffers − It is a technique for extracting information from network traffic to harvest passwords. Hackers used to target sessions to steal credentials and other information. Websites that don't have an SSL protocol encryption to protect themselves are vulnerable to attack and exploitation.

Use of Network Sniffers

Hackers primarily employ network sniffers to gather information on passwords and other sensitive information. The sniffer decodes data in packets travelling from source to destination, between client and server, or between organisations. They functioned as middlemen and employed a packet injection attack to grab the data. For example, a network sniffer can track down someone using too much bandwidth at a university or company by monitoring network traffic. They are also used to detect security vulnerabilities in our system.

Today, however, black hat hacking is a widespread application for them. In the wrong hands, network sniffing tools can allow anyone with little to no hacking expertise to monitor network traffic across unsecured WiFi networks to steal passwords and other sensitive data. This reason can give network sniffing tools a bad name, yet network sniffers have many valid purposes.

How Does Sniffing Work?

With the software's assistance for sniffing data packets, the Network sniffing tool intercepts and logs the network traffic. This software allows you to access information from a whole network or just a segment of one.

As we all know, networks are used to send packets of data. The data can be large, and transmitting it all in one packet places a load on the network, compromising the data's integrity. As a result, once a data file is sent, it is usually broken down into small parts and sent to the intended location.

The destination address, number of packets, reassembly order, and source address are all included in the data packet. The data packet's footers and headers were erased after it arrived at its destination. A filter on the network can delete packets that are not addressed to the same network.

Following the receipt of network data, the following steps are taken −

  • Individual packets (sections of network data) or their contents are recorded.

  • Software only saves the header segment of data packets to save space.

  • The user can access and evaluate the information when the network data has been decoded and formatted.

  • Packet sniffers examine network communication failures, troubleshoot network connections, and reconstruct whole datastreams meant for other computers.

  • Some network sniffing applications retrieve passwords, PINs, and other confidential information.

Network Sniffer Tools

There are a lot of network sniffer tools out there. These tools continuously monitor or sniff data flowing via computer network links. This software tool might be a standalone program or a physical device with the necessary software or firmware.

Sniffers capture snapshots of data flowing across a network without rerouting or modifying it. Some sniffers are only compatible with TCP/IP packets, but more advanced tools work with a wide range of network protocols and at lower levels, including Ethernet frames. Each tool has its own set of features and benefits.

Some of the popular network sniffing tools are −

  • Wireshark,
  • TCPdump,
  • Microsoft Message Analyzer,
  • Ether App, and
  • Network Miner.

Any information can be captured, such as the websites visited by the user, contents on the websites or emails, and details about any downloaded files using a sniffer tool. Businesses frequently use protocol analyzers to track employee network usage and are included in many reputable antivirus software packages. Outward-facing sniffers examine incoming network traffic for specific elements of malicious code, assisting in preventing computer virus infections and the spread of malware.