What is Network Sniffing in Cyber Security? Explained

Network Sniffing in Cyber Security is the process of recording all the data packets that go through a network. Network administrators use sniffers to monitor and troubleshoot network traffic. However, hackers often misuse these sniffers to intercept sensitive data packets containing information like login credentials and financial details. You can deploy sniffers as either software or hardware. Attackers deploy their sniffers to monitor all the network traffic for their benefit.

Network sniffers are also called packet sniffers, as essentially all data on a network is distributed into packets. Authorities deploy packet sniffers to investigate cybercrime, such as theft, impersonation data breaches, etc. These packet sniffers can also be used ethically to access sensitive information.

What are the Different Types of Network Sniffing in Cyber Security?

Network Sniffing has two types:

• Active Sniffing

Active Sniffing is when the sniffing is done in the switch. A switch is a device that provides a connection between two points inside a network. Switch continuously checks the MAC address on both ends to ensure that the data is reaching the correct location. The sniffer tracks all communication on both ends by spiking the traffic inside the LAN. You can perform active sniffing in multiple ways.

• Passive Sniffing

In passive sniffing, the attackers do not engage directly with the target. Instead, they connect with the network and collect the data packets being sent between two ends or two different devices. Attackers only need a LAN account, and by using that, they connect to the hub using their PC to sniff on users.

Types of Network Sniffers

Below are different types of Network Sniffers mentioned −

• Mac sniffers − Data relevant to the MAC address is sniffed by this type of sniffer.
  Protocol sniffer − Involves sniffing data from the network to the network protocol.
• LAN sniffer − They are deployed inside internal and organizational networks and are capable of sniffing all the IP addresses within the network.
• IP sniffers − IP sniffers target specific IPs to check out for the network performance, accessibility, and vulnerability. After gathering information on the vulnerabilities the hackers use them to attack the network to access key sensitive information such as passwords.
• ARP sniffers −ARP sniffers map MAC addresses to IP addresses. By sending bogus replies, they direct the traffic to their own devices. By doing so, they can implement man in a middle attack and modify, delete, or block the data according to their will to fulfill their objectives.
• Password sniffers − A Password sniffer specifically targets the packets involving the password data. They engage from session to session to steal the credentials of users.

How Does Sniffing Work?

With network sniffing software in place, a sniffing tool captures and logs network traffic. It can monitor an entire network or just a specific subnet. As data is transmitted across a network, it’s split into smaller packets to reduce load and ensure integrity.

Each packet carries source/destination addresses, packet sequence information, and routing metadata. Once it reaches its destination, the packet’s headers and footers are removed, and any packets not addressed to the network are discarded.

After capturing data, the tool proceeds as follows:

• Logs individual packets or their contents.
• Often, stores only packet headers to conserve storage.
• Decodes and formats the captured data, making it accessible and readable.
• Enables the user to analyze and interpret the network communication.

Network administrators use packet sniffers to diagnose failures, troubleshoot connectivity issues, and reconstruct full data streams meant for other hosts. Some sniffers can also extract sensitive information—like passwords or PINs—from unencrypted packets.

Key Insights of Network Sniffing in Cyber Security

Packet capture: Tools like Wireshark and tcpdump intercept and log packets by operating network interfaces in promiscuous mode.

• Storage efficiency: Many sniffers preserve only header information unless deeper analysis is needed.
• Analysis & decoding: Captured traffic is decoded and formatted to reveal protocol layers and payload content.
• Use cases: Sniffers assist with network diagnostics and security monitoring and can extract credentials when data is sent unencrypted.

Network Sniffer Tools

Network sniffer tools continuously capture and log data passing through network links—either across the entire network or just a specific segment. They may exist as standalone software or as hardware appliances equipped with specialized firmware.

These sniffers take non-intrusive “snapshots” of network traffic without altering it. While some focus primarily on TCP/IP packets, advanced tools operate at deeper levels—such as capturing Ethernet frames—and often support a wide array of network protocols. Each tool brings its features and strengths to the table.

Common Packet Sniffing Tools

• Wireshark – A free, open-source GUI-based protocol analyzer renowned for detailed packet inspection.
• tcpdump – A powerful command-line packet capture utility based on libpcap
• Microsoft Message Analyzer – Windows-based packet and protocol analysis tool
  Ether App & Network Miner – Useful for passive capture, traffic reconstruction, and forensics

What Can Sniffers Detect?

Sniffers can reveal:

• Visited websites and their content
• Email contents and file downloads
• Breach indicators and malware signatures

This makes them valuable for network usage monitoring, malware detection, and Digital Forensics Investigation Techniques within organizations.

Why They Matter

• Network troubleshooting: Identify bottlenecks, misconfigurations, or failing devices
• Security monitoring: Detect malicious payloads and unauthorized data flows
• Employee activity audits: Track usage and enforce policy compliance

In essence, packet sniffers—also known as packet or protocol analyzers—can be powerful tools for both network management and security. Their capabilities range from traffic inspection and protocol analysis to credential extraction when used on unencrypted traffic.

Use of Network Sniffers

Hackers often use network sniffers to intercept passwords and other sensitive data transmitted between endpoints, such as client-to-server or between organizations. These tools act as covert intermediaries, capturing and sometimes injecting packets to hijack data flows.

For example, a sniffer can monitor bandwidth usage on a campus or corporate network or identify security weaknesses. Today, black hat attackers frequently exploit sniffers—especially over unsecured Wi‑Fi networks—to harvest unencrypted credentials and personal information with minimal technical expertise. While this misuse contributes to their negative reputation, network sniffers remain valuable for legitimate purposes like troubleshooting, performance monitoring, and security analysis.

Conclusion

Sniffing uses various tools to actively or passively monitor data packets on a network and capture important information. That’s why it’s crucial to address the threat of email spoofing. You can contact our team at Cybersics to learn more about how to control it.