What Is a Packet Sniffing and How to Prevent It?

  • By Bree Ann Russ
  • Published: Sep 11, 2023
  • Last Updated: Nov 23, 2023

what is packet sniffing

It's difficult to fathom how much information passes through a single website daily. On the extreme side of things, Google, YouTube, and Facebook had 28 billion combined visits in June 2023 alone. These sites receive information on people's hobbies, favorite foods, geographic location, and more.

Information like that is a gold mine no matter what side of cyberlaw you stand on. So, it's not surprising that people on both sides are going to round up as much of it as they can. That's where packet sniffing comes in.

What is a Data Packet?

A data packet is the term used for a segment of user information moving across a network. Data packets don't include the entire "message" but are broken down into smaller parts at each of the network's many nodes before recombining at the end device. This process makes it more challenging to decipher the original message because the data isn't complete until the final node.

However, data packets include more than what the user intended. They also store various metadata, such as the origin IP address and the submission time. Information like this can sometimes be enough to endanger your online privacy.

What is Packet Sniffing?

Packet sniffing is a technique used in cybersecurity and hacking to collect and store all the data packets entering a server. These packets are analyzed to learn more about the users they originated from.

For network administrators, this helps them better understand traffic, user interaction, and other performance statistics. The data packets are like clues to figure out the pain points in the server, application, or user experience.

However, cybercriminals perform network sniffing to read unencrypted emails or steal sensitive personal data. They're more like the beach walker with a metal detector. He only needs to find one coin in the sand to go home a happy man.

Types of Packet Sniffers

There are two main types of packet sniffers. Which one you use will vary according to your goals.

Hardware Packet Sniffers

Hardware packet sniffers plug directly into the physical network. This application prevents missed data from filtering, routing, or other errors. Hardware sniffers may remotely forward the collected data to another device but will likely store the information.

Software Packet Sniffers

Most businesses utilize firewalls or some other security measure that restricts incoming traffic. Doing so is a must to prevent malware from strolling unimpeded into their servers. However, software packet sniffers turn off these restrictions and accept all incoming traffic. This setting is humorously named "promiscuous mode."

As their name suggests, software sniffers are programs run on an endpoint device connected to the target network. This connection can be over Wi-Fi, Ethernet, or LAN, but many programs require a specific type.

How Does Packet Sniffing Work?

When data splits into packets across a network, those packets are assigned a final node to recombine at. This assignment lets every node between the first and last understand which data packets are incomplete and don't need to be checked.

Packet sniffing applications circumvent this check and read the information of every data packet passing through. They're typically set up in a network's Transmission Control Protocol/Internet Protocol (TCP/IP) layer.

Administrators who want to collect all the data on a network will require multiple network sniffers. The exact number depends on how the network is set up and the number of routers used. Hackers are rarely interested in a holistic view of a network since they're fishing for specific information.

Active Sniffing

Active sniffing has the perpetrator directly interact with the network through switches. A switch records the relationships between ports on a network and sends data to specific MAC addresses. Once the switch can no longer store these relationships, it will "overflow" and allow the attacker to sniff legitimate traffic over the switch.

Common examples of active sniffing include DNS spoofing, MAC flooding, and ARP spoofing.

Passive Sniffing

While it's challenging to detect active sniffing, passive sniffing is undetectable. Rather than interact directly with the target network, the attacker injects a sniffer into the network hub and passively listens in. This type of attack can be beneficial for gathering information about targets on a network and the types of data (e.g., login credentials, email messages) they are transmitting. Hubs are mostly phased out of use, which makes passive sniffing attacks a rarity.

How to Protect Yourself from Packet Sniffing

Packet sniffing attacks are rising in popularity. The practice has a legitimate use for website administrators, so there's no shortage of options for hackers to abuse. While organizations must do their part to protect your data, here are a few things you can start doing to take control of your online safety.

Avoid Public or Unsecured Wi-Fi Connections

avoid unnsecured Wi-Fi connections

If you're well-read on the internet's many dangers, you've seen this tip a few hundred times. Public Wi-Fi networks expose your device to the swords and spears of the lazy hacker. The complimentary airport Wi-Fi or the "conveniently" open hotspot lacks a well-configured firewall or AI threat detection. Criminals can install packet sniffers and collect your data at absolutely no risk to themselves.

One of the most popular packet sniffing attacks is password sniffing. This tactic is almost always performed over public Wi-Fi. If you’re in a do-or-die situation and must use unsecure networks, make sure to avoid accessing financial accounts and install a VPN first.

Take Advantage of Virtual Private Networks (VPN)

VPNs are like hacker holy water. These services encrypt all your data, so even if a hacker reads your packet, they'll only see a useless string of random characters. Additionally, VPNs first send your data through the provider's personal servers, preventing sniffers from reading your IP address from a packet's metadata.

Check for Security Protocols

Everybody knows about Hypertext Transfer Protocol Secure or HTTPS. Otherwise known as the part of the web address you never typed in.

HTTPS' presence meant that the website met higher standards regarding user data. The website must encrypt incoming data and have measures to prevent third-party tampering. Nowadays, a secure site is marked by the lock icon on the address bar's far left end.

Tighten Your Endpoint Security

Endpoints represent an inside track into an organization's network. Leaving your laptop unattended or your desk unmanned is all the opening a sniffer needs. Installing a robust antivirus program on all your devices is ideal for detecting unwanted software. If you feel like your device has already been compromised, we recommend performing a factory reset as soon as possible.

Watch Out for Social Engineering Attacks

We've all heard of the infamous Nigerian Prince scam. Attacks that prey on our emotions are famously mocked, but they're surprisingly effective in the heat of the moment. Nobody relishes the idea of being sued, sick, or berated, and phishing emails often threaten all three.

Most importantly, the scam only needs to work once. Attackers target hundreds of employees at a time with phishing emails, hoping that one of them makes a mistake. These attacks aren't typically sniffer threats but could download even more dangerous malware.

Protect Yourself from Packet Sniffing Threats

Packet sniffing is a powerful tool used in both cybercrime and legitimate business. However, it's pretty easy to protect yourself from these threats. Installing a VPN and sticking to secure URLs will eliminate 99 percent of the risk to your data and privacy.

Businesses and organizations must take steps to prepare as well. Educating your employees on identifying suspicious emails and integrating endpoint security options will go further than you think! If you need more ideas, InfoPay has dozens of posts explaining the internet's many threats and how to face them.

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