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Kali Linux 2025.7 DNS Fix

Abstract

In certain cases, an interaction between the sslh and systemd packages in Kali Linux can prevent essential services from starting. While this affects only a small subset of systems, it disrupts the automated exercise setup process and leads to inconsistent system behavior and user experience. This article describes the symptoms of the issue and outlines solutions for both deployed and copied Kali Linux 2025.7 environments within the U.S. Cyber Range.

Impacted Environments

This impacts Kali Linux-based images released as part of our Fall releases for 2025 (“2025.7”), which include:

  • Environment: Cyber Basics (2025.7)
  • Environment: K12 Cyber Security Concepts Using Kali Linux (2025.7)
  • Environment: Kali Linux - Desktop (2025.7)
  • Environment: Kali Linux - Terminal (2025.7)
  • Environment: Kali Linux and Vulnerable Windows 7 (2025.7)
  • Environment: Kali Linux and Windows Server 2019 (2025.7)
  • Environment: Kali Linux with Metasploitable3 (2025.7)
  • Environment: Kali Linux with Vulnerable Targets (2025.7)
  • Shared Networks Env: Kali Desktop (2025.7)
  • Shared Networks Env: OPNsense Firewall with Multiple Networks - Kali and two Ubuntu servers (2025.7)

Symptoms

Symptoms of impacted virtual machines affected by this issue:

  • Trying to load a web page at “*.example.com” does not load the web page
  • Network tools targeting “*.example.com” complain that the target is not found
  • The hostname of the Kali machine does not end in “example.com” when it normally would

Solutions

Existing Environments

Unfortunately, virtual machines that are already impacted cannot be fixed and must be redeployed, as this issue does not occur in new exercises. Existing student work should be saved or backed up elsewhere before choosing one of the options below:

  1. Delete the exercise group as a whole and then re-add it to the course. (Choose this option if your entire class is affected or if the exercise environments haven't been started yet)
  2. Use the “reinstall” button in impacted exercise environments to provision a new exercise. (Choose this option if not every user reports the issue)

Note

Please visit our How To Restart or Reinstall an Exercise Environment article for questions on how to reinstall an exercise environment.

Copied Environments

If you’ve made a copy of the impacted exercise environments before October 2nd, 2025, then we recommend creating a new copy, as it will not contain the bug.

However, if you wish to preserve your copied environment, you can fix it by deploying said environment and then entering this command:

sudo install -Dm755 /dev/stdin /etc/systemd/system-generators/systemd-sslh-generator <<< $'#!/bin/sh\nexit 0\n' && sudo systemctl daemon-reexec

You'll then need to create a new copy of the environment once the process has finished.

Once the environment has been successfully copied, you should use the new version, as it will not be impacted by the issue anymore. Once you’ve ensured that this new copied environment works as expected, we also recommend deleting the old version so it's not accidentally used in the future.

Have a Question? Contact Support

We're here to help you. If you still have questions after reviewing the information above, please feel free to submit a ticket with our Support Team and we'll get back to you as soon as possible.