What Is a Network Sniffer?

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Network sniffing is the use of a tool called a network sniffer that tracks or sniffs the data flowing in real-time over computer network connections.


This software tool is either a self-contained software program or a hardware computer that has the necessary software or firmware.

Sniffers are not bad news all the time. In certain instances, sniffing methods are used by administrators to maintain a steady traffic flow across their networks.

Bandwidth hogs, such as someone who makes heavy use of file-sharing programs, may be detected and then take corrective action.

What is a Network Sniffer?

Without redirecting or changing it, network sniffers take screenshot copies of the data flowing over a network.

Some sniffers only function with TCP/IP packets, but with many other network protocols and at lower levels, like Ethernet frames, the more advanced tools can work.

Sniffers were devices used primarily by professional network engineers years earlier. Nowadays, however, they are also common with Internet hackers and individuals who are curious about networking with software accessible for free on the web.

How do network admins use tools for sniffing? First, understanding how internet traffic typically functions over a network is crucial.

Your machine can only investigate packets that have been directly addressed to it in most cases. We can imagine your machine as a house along that lane, going back to the “cars driving on the road” metaphor.

You’re not going to check every car driving around your building, but if someone parks in your driveway, you’re definitely going to open the door to see who it is.

This is how your computer handles most data packets: it ignores the ones going to other destinations in the network when reviewing the packets that are sent to it.

Sniffing software modifies the network settings of a device so that each packet “sniffs” instead of only those sent to it and copies them all for later investigation.

How Packet Analysers Are Used

There’s a wide variety of packet sniffer applications. Many packet sniffers can be misused by one person and by another for legitimate reasons.

For example, a program that collects passwords might be used by a hacker, but a network administrator could use the same tool to find network statistics, such as usable bandwidth.

Network sniffing is also used for firewall or site filter checking and client/server relationship troubleshooting.

Legitimate uses for sniffing software

To tap into its traffic and monitor what is being sent, professional technicians position sniffers within a network.

Here’s a list of individuals who could use a network sniffer:

  • Network engineers: Engineers may use the data to optimize the configuration of their network for reliability and speed by analyzing the nature and level of traffic on a network.
  • System admins: Network sniffers are incredible tools for troubleshooting. Sysadmins will plunge into bottlenecks or other slowdowns as the problem is investigated.
  • Employers: IT technicians can use sniffers at a corporate office to track their employees while at work. Employers will learn about the websites their staff visit, how much time they spend there, and if they shouldn’t be watching or downloading something.
  • Security professionals: Unusual volumes or types of traffic may mean that not everything is as it appears. Security teams may detect atypical patterns of internet use that may suggest a hacker or malware’s presence.

Ilegal uses for sniffing software.

Cybercriminals can hack into a network and control all the traffic sent through it to help themselves. A hacker can be able to access login credentials, insider info, and financial data by tracking internet use, including emails and instant messages.

That is why, in the wrong hands, sniffers can be so dangerous. And there are plenty of free online sniffers available: music to the ears of a cybercriminal.

To fool their victims into installing their sniffers, cybercriminals will use social engineering tactics or phishing scams. They can direct targets to infected websites that, when accessed, download the sniffer automatically or send emails with attachments that can install the malicious software.

The security issues and risk factors that could arise as a result of downloading such software is unimaginable.

Hackers can sniff unsecured public wifi networks, alternatively, ensnaring the traffic of anyone who uses them. In spoofing attacks, wireless sniffers are extremely common, as the cybercriminal can use the data collected by the sniffer to “spoof” a computer on the wireless network.

How Network Sniffing Works

All data flowing over the network is detected by a packet sniffer linked to every network.

Computers usually communicate directly with other computers or devices on the network over a local area network (LAN). Any of the traffic is exposed to everything linked to that network. To ignore all network traffic not intended for it, computers are configured.

By opening up the computer’s network interface card (NIC) to listen to that traffic, network sniffing software opens up to all traffic. The program reads the information and conducts analysis or retrieval of data on it.

The program performs the following actions on it after it receives network data:

  • The contents, or individual packets (network data sections), are registered.
  • In order to save space, some software only records the header portion of data packets.
  • Network data collected is decoded and formatted so that the user can access the information.
  • Packet sniffers analyse network connectivity failures, troubleshoot network links, and restore entire data streams intended for other computers.
  • Sensitive information such as passwords, PINs and private information is obtained by certain network sniffing tools.

Types of Sniffing techniques

There are two major types of strategies for sniffing: passive and passive sniffing.

Option 1: Passive sniffing

Hubs are basic networking devices linking several devices into a single network together. There are no regulatory frameworks that direct traffic to its intended recipient; instead, all devices receive all the traffic and then decide whether that traffic is necessary or not.

Since all devices in a hub receive all the traffic from the network, a sniffer can quickly and passively soak up all that is sent. In fact, there’s nothing to do other than sit back and sniff. This makes it really hard to detect passive sniffing. Not impossible, but demanding.

Option 2: Active sniffing

The higher levels of traffic can get overwhelming when you attach extra devices to a hub. The solution to this problem is network switches.

Switches monitor traffic within a network by explicitly transmitting data to the system that is supposed to receive it. Only the data passing to and from its host computer would be accessible to a passive sniffer on a network hub.

This is where it comes into play with active sniffing. An successful sniffer needs to get around or conquer the way switches direct all in order to access all the traffic going through the network.

There are a few nifty ways to do this, but they all include adding extra traffic into the network. This is what makes it an active operation, and what separates the passive variety from active sniffing.

The upside for future victims is that it is easier to spot an aggressive sniffer because it gives away its own presence.

How to Thwart Network Sniffer Attacks

There are ways to defend yourself if you’re worried about network sniffing apps spying on the network traffic coming from your computer.

There are ethical reasons why sniffer software will need to be used, such as when a network administrator controls the flow of network traffic.

They use anti-sniff scans to protect against sniffer attacks when network administrators are worried about the nefarious use of these tools on their network. This implies that corporate networks are typically stable.

However, for nefarious purposes, it’s easy to acquire and use sniffer software, which makes the illegal use of your home internet a cause for concern. It would be very smooth for someone to link even a corporate computer network to such applications.


Use a VPN (Virtual private networks) that encrypts your internet traffic if you want to shield yourself from someone spying on your internet traffic. IP addresses are the target during sniffing attacks, and you can protect your IP address with a VPN.

Avoid unencrypted messaging apps

Unencrypted messages are easy bait for sniffers, much like unsecured WI-FI. For end-to-end security, choose to chat with your friends and family through an app that encrypts messages.

A wide range of the most popular choices are WhatsApp, Viber, Thread, and Telegram. The chances are that one of those is already used by you and your contacts. Unencrypted messaging apps pose security risks.

Avoid Unencrypted sites

Individual users can easily carry out basic Http Authentication before using a site. Take a quick look at this website’s URL. See how it begins with ‘HTTPS’ starts? You could also be shown a little padlock icon next to the URL in your browser. The S stands for “secure” when you see HTTPS.

Websites using HTTPS are encrypted, and while you’re there, your activity on those websites is covered. This padlock icon is only one of the indicators that you can use to decide whether a website is safe or not.

Website addresses with HTTP instead of HTTPS, on the other hand, do not have the same level of protection. There’s no guarantee when you visit these places that anyone won’t be watching. Never enter any personal information, not even a password, if you have to go to a site without HTTPS security.

It is imperative to remember that you are only secured by HTTPS encryption on website addresses. Use a VPN for extensive online data encryption Using a VPN for extensive online data encryption as unsecured networks may pose security risks.

Avoid public wifi

Free and unsecured WI-FI networks, especially given how costly some mobile data plans can be, is a tempting offer. But if you’re not defending yourself, avoid the temptation to get on an insecure wifi network behind a VPN.

Your data can be supported by someone else linked to that hotspot.

Think of how many people are linked to each other at an airport, a mall, or even a cafe. When you use unsecured public WI-FI, the possibility that no one is sniffing at that time is gambling with your personal data.

How to detect the presence of a sniffer

Identifying a passive sniffer’s presence is not an easy job. Passive wifi sniffers are practically invisible, and so encryption is the best defense against them. You’ll struggle with active sniffing if you’re on a switched network, which leaves ripples in its wake.

Network administrators are qualified to look for such signs, and they will understand how to respond accordingly.

On my own machine, can I detect a sniffer?

It’s not always possible to specifically detect a sniffer. However, you can look for the following signs if you suspect you’re hosting a sniffer:

  • Unexplained processes: Often sniffers run at the user level of a machine, meaning the user accounts of the computer (like you) will be able to see them working.
  • Sudden storage reduction: With a rootkit, some sniffers may cover themselves. But even the super-stealthy sniffers need somewhere to place their files. An unexplained loss may mean a sniffer on your computer in storage space.

Issues with sniffers

A perfect way to learn how network protocols operate is provided through Sniffer software. They also, however, provide easy access to such private data, such as network passwords. Before using a sniffer on their network, check with the owners to get permission.

Network probes only intercept data from networks that are connected to their host computer. Sniffers only capture the traffic addressed to that particular network interface on some connections.

In any case, the most significant thing to remember is that if that traffic is encrypted, anyone looking to use a network sniffer to spy on traffic will have a hard time doing so.

In conclusion

There is no such thing as natural security on the web. For this reason, every user has a responsibility to take protective measures if they must avoid cases like sniffer attacks. Always opt for antivirus software for your windows and Linux devices.

Your credit card details and more can be stolen during such attacks, so be at Alert always. Also, pay more attention when you notice network issues or suspect there may be network congestion.

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