As an ethical hacking platform, Kali Linux has seen massive adoption over the past few years. According to recent surveys, over 30% of cybersecurity professionals now utilize Kali as their go-to penetration testing toolkit.1 With open-source development on the rise as well, many developers are also turning to Kali for building security tools and customized distros.
However, taking full advantage of Kali‘s capabilities often requires installing additional packages beyond the default image. One of the most common needs is installing Linux kernel headers and associated files.
Understanding Linux Headers: A Primer for Developers
For programmers and compiled software to properly interface with the Linux kernel, header files are required. These expose various kernel APIs, structures, and interfaces to userspace.2
Here are some specific reasons developers require access to up-to-date Linux headers on Kali Linux:
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Building External Kernel Modules: Creating virtual network drivers, security modules, or hardware drivers involves kernel headers for compiling.
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Userspace Development & Debugging: Headers allow tracing syscalls and ABI details during complex application coding.
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Custom Kernel and OS Development: Modifying, porting or writing kernels leverages headers for accessing internals.
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Binding Languages to System Calls: Languages like Go and Rust rely on headers for system call bindings and access from userspace code.
Simply put, Linux headers act as the gateway between user applications and the kernel itself. Making them essential for systems development on Kali.
Checking Current Kernel Version on Kali
With the basics covered, let‘s dive into the installation process. We‘ll be using the command line exclusively here.
First, verify your current Kali kernel release with:
uname -rTake note of the full version string. Next, check your overall distro release with:
lsb_release -aOn a current Rolling release, you would see:
Kali GNU/Linux Rolling
Linux kali 5.10.0-kali7-amd64 #1 SMP Debian 5.10.13-1kali1 (2021-03-30) x86_64 GNU/LinuxNow that we know the OS and kernel details, we can fetch the proper headers.
Updating Repositories and Packages
With any Linux environment, it‘s smart to update the package manager before installing anything new.
On Kali, run:
sudo apt update
sudo apt full-upgradeGrab a coffee while this completes! It syncs your local APT repository to the latest upstream packages.
Once finished, reboot or log out and back in to load the newest kernel and system libraries.
sudo reboot nowAfter your system restarts, log back in and check uname -r to confirm the expected kernel is running.
Now we are ready to install our headers!
Installing Kali Linux Headers with APT
The easiest method for installing current Linux headers is using Kali‘s built-in APT package manager.
Simply execute:
sudo apt install linux-headers-$(uname -r)Assuming you are running the latest kernel, this will grab and install the matching headers package.
For example, given a kernel version of 5.10.0-kali7-amd64, the linux-headers-5.10.0-kali7-amd64 package is retrieved.
If you happen to get any dependency or repository errors, first run:
sudo apt --fix-broken installThis attempts to fix any issues with missing or corrupted packages. Try installing the headers again after.
Downloading and Manual Header Installation
An alternative approach is to directly download and install Kali kernel headers manually using the dpkg utility. This comes in handy if the APT repositories don‘t contain the headers for your specific kernel version yet.
Browse to http://http.kali.org/kali/pool/main/l/linux/ and navigate to the headers package matching your uname -r output.
For a kernel release like 5.10.7-amd64 you would grab:
linux-headers-5.10.0-kali7_5.10.7-1kali1_amd64.debDownload this package file to your Kali system. Then install it with:
sudo dpkg -i linux-headers-5.10.0-kali7_5.10.7-1kali1_amd64.debSwap out the filename as needed. This manually forces the headers DEB package to be installed.
Verifying Linux Header Installation
With headers installed via either method, we can double check everything completed successfully:
uname -r
find /usr/src -type d -name "linux-headers-$(uname -r)" This prints your current kernel version, then searches /usr/src for the matching header directory.
Output would show:
5.10.0-kali7-amd64
/usr/src/linux-headers-5.10.0-kali7-amd64If nothing shows up or the header path does not match, your headers are not properly installed for the running kernel.
Troubleshooting: Handling Install Errors
If you receive dependency or package broken errors, first update APT again:
sudo apt update
sudo apt dist-upgradeThen retry installing linux-headers. This syncs to upstream and installs all latest packages.
For header specific issues, you can force install the DEB file:
sudo dpkg -i --force-depends linux-headers-<version>.debThis disregards missing dependency or version complaints and installs anyway.
Finally, as a last resort with major package issues you can reinstall Kali Linux cleanly from ISO keeping your existing home folder.
Developing External Modules Against Kali Headers
With headers fully installed, you can now develop external kernel modules leveraging Kali‘s kernel APIs.
Here is a quick example building a simple "Hello World" kernel module against the headers:
// helloworld.c
#include <linux/module.h>
#define INCLUDE_VERMAGIC
#include <linux/build-salt.h>
#include <linux/vermagic.h>
MODULE_LICENSE("GPL");
static int __init hello_init(void) {
printk(KERN_ALERT "Hello World!\n");
return 0;
}
static void __exit hello_exit(void) {
printk(KERN_ALERT "Goodbye World!\n");
}
module_init(hello_init);
module_exit(hello_exit);To build:
gcc -c helloworld.c -I /usr/src/linux-headers-$(uname -r)/include
gcc -o helloworld.ko helloworld.o -L /usr/src/linux-headers-$(uname -r)/Finally insert the module with insmod helloworld.ko and check output with dmesg.
This shows how newly installed headers connect user code to kernel internals.
Conclusion: Enjoy Full Development Capabilities
In closing, installing Linux headers opens up the full software development capabilities of Kali Linux allowing kernel and systems level programming.
Now you know exactly how to get up and running building external modules, debugging complex applications, writing language bindings, customizing the kernel, and much more!
With headers installed, take advantage of Kali‘s advanced development features for crafting your own pentesting tools and network analysis utilities!