Creating a Blacklist

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Creating a Blacklist

The aim of this lab is to create a blacklist with firewalld. A blacklist can be populated with any set of IP addresses that are either downloaded from the Internet, custom-created by you, or a combination of both. When populating a blacklist of your own, you can do it by gradually adding a certain number of IP addresses over a period of time and expanding the list that way. You need to examine the log files first, see which IP addresses have been making requests, and investigate these requests. If the requests seem malicious or if, for some reason, you do not want a particular IP address to send you any requests, all you have to do is add that IP address to the blacklist. Eventually, you will notice that the number of malicious requests will decrease, though they will never completely stop.

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Lab Info

Level

Intermediate

Last updated

Sep 22, 2025

Duration

30m

Challenge

Create a New Blacklist

Create a new IP set called "blacklist," and set its type to "hash" with a hash size of 4096 and a max elem of 20,000 (or any value you choose).
Challenge

Create a List of IP Addresses and Put Them into a File
1. Open log files and grab a few IP addresses from there. Make sure you do not ban yourself!
2. Populate the MyIpList file with IP addresses.
3. Save and close the MyIpList file.
Challenge

Add the IP Addresses to the Blacklist

Add entries from MyIpList to the blacklist IP set.
Challenge

Add the Blacklist to a Drop Zone
1. Add the blacklist IP set to a drop zone.
2. Reload firewalld to apply all these changes.

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