Select language
Avast Academy Security Other Threats What is a Sniffer and How Can I Protect Against Them?

What is a Sniffer and How Can
I Protect Against Them?

Sniffers come in many forms: packet sniffers, Wi-Fi sniffers, network sniffers, and IP sniffers, for example. But they all have one thing in common – they steal all the traffic flowing into and out of a computer.


What is a sniffer?

A sniffer isn’t necessarily malicious. In fact, this software is commonly used to monitor and analyze network traffic in order to detect problems and keep things flowing efficiently. But a sniffer can also be used for ill intent. Sniffers track everything that goes through them, including unencrypted passwords and usernames so hackers who can access a sniffer can access any accounts that go through them. Additionally, a sniffer can be installed on any computer connected to a local network without needing to be installed on the device itself – in other words, it can go undetected for the duration of the connection.

Hamburguer menu icon

This article contains:

    Where do sniffers come from?

    Hackers use sniffers to steal data, spy on network activity, and collect information on users. Usually, the end goal is to obtain passwords and account information for banking and shopping sites. Typically hackers place sniffers in places that offer unsecured Wi-Fi connections such as those found at coffee shops, hotels, and airports. Sniffers are also used to impersonate other devices on the network in what’s known as a spoofing attack in order to steal sensitive information.

    How do you recognize a sniffer?

    Unauthorized sniffers can be virtually impossible to detect and can be inserted almost anywhere, making them extremely dangerous to a network's security. Basic users will likely never know if a sniffer is spying on their network data. You could, in theory, run your own sniffer and monitor DNS traffic to find other sniffers, but for the standard user it’s much simpler to run anti-sniffer software to catch any intruders, or to use an internet security program that will hide your browsing activity.

    How to remove a sniffer

    You can use a powerful antivirus to find and remove any malware associated with a sniffer that’s been installed on your computer. But to completely purge a sniffer from your computer, you’ll need to delete the files and folders associated with it. To remove a sniffer that’s been surreptitiously installed on your network, on the other hand, you’ll want to use internet security software that includes a network scanner, which will search for any issues on your network and instruct you on how to deal with them.

    How to prevent a sniffer

    • Encrypt everything you send or receive

    • Scan your networks for any issues or dangers

    • Use only trusted Wi-Fi networks

    Protect yourself against a sniffer

    The first thing you can do to protect yourself is to use antivirus software, such as Avast Free Antivirus, that allows you to scan your network for issues. But the best way to protect yourself from sniffing is to encrypt all sensitive data sent online, including emails. Avast SecureLine allows you to go completely private on any network by encrypting everything you send and receive.

    Protect your iPhone from threats
    with free Avast Mobile Security


    Protect your Android from threats
    with free Avast Mobile Security