Monitor Linux DNS traffic using eBPF

🔎 Linux host monitoring and threat detection with eBPF

Lightweight and high-performance monitoring and security tool that utilizes eBPF and Python to provide real-time DNS monitoring. By executing in kernel space, eBPF tool avoids costly context switches and offers efficient detection and prevention of malicious behavior on your network through monitoring of outbound connections

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Table of Contents

• Introduction
• Dependencies
• Usage
• Running script as a systemd service
• Logging

Introduction 🌼

Powerful monitoring tool focused on DNS monitoring, utilizes the power of eBPF and python to provide real-time monitoring and actionable insights for identifying and mitigating potential threats.

The tool is an alternative monitoring solution for DNS traffic. Based on open-source eBPF tool for DNS monitoring by Nurkholish Halim.

The source gist may be found here.

Dependencies 🧵

Installation

apt install python3-bpfcc bpfcc-tools libbpfcc linux-headers-$(uname -r)

Usage ⚙

This tool captures outbound DNS requests and responces on a eBPF level.

Run python3 ebpf_dns_main.py to get started. Note: based on your Linux kernel version, it may require sudo privileges.

$ root@host:~/# python3 ebpf_dns_main.py

Sample Output:

The program is running. Press Ctrl-C to abort.
2023-08-27T17:43:21Z COMM=systemd-resolve PID=645 TGID=645 DEV=ens33 PROTO=UDP SRC=192.168.40.130 DST=192.168.40.2 SPT=47892 DPT=53 UID=101 GID=103 DNS_QR=0 DNS_NAME=visitukraine.today. DNS_TYPE=A
2023-08-27T17:43:21Z COMM=systemd-resolve PID=645 TGID=645 DEV=ens33 PROTO=UDP SRC=192.168.40.2 DST=192.168.40.130 SPT=53 DPT=47892 UID=101 GID=103 DNS_QR=1 DNS_NAME=visitukraine.today. DNS_TYPE=A DNS_DATA=104.21.71.200

Running script as a systemd service

To set up script automatically run as a service, copy main script to the /etc/ebpf-dns-monitor, and the ebpf-dns-monitor.service to the /etc/systemd/system/

Create a new folder under /etc:

sudo mkdir /etc/ebpf-dns-monitor.

Copy the main .py script to the folder.

cp ebpf-dns-main.py /etc/ebpf-dns-monitor/

Copy .service file to the /etc/systemd/system/.

cp ebpf-dns-monitor.service /etc/systemd/system/

Reload the daemon.

sudo systemctl daemon-reload

Now we can enable the new service and start it.

sudo systemctl enable ebpf-dns-monitor.service
sudo systemctl start ebpf-dns-monitor.service
sudo systemctl status ebpf-dns-monitor.service

Logging 📈

The app will log all the request and responses to /var/log/ebpf-dns-monitor.log which can be easily monitored with Log management solutions(SIEM). The datetime format is RFC 3339.