missing privilege separation directory run sshd

3 min read 01-10-2024

When dealing with Secure Shell (SSH) on Unix-like systems, you may encounter the warning: "missing privilege separation directory: run/sshd". This error can be puzzling, especially for those new to server management or SSH configuration. In this article, we will delve into what this message means, how to resolve it, and best practices for maintaining a secure SSH setup.

What is Privilege Separation in SSH?

Privilege separation is a security feature implemented in OpenSSH that allows the SSH daemon (sshd) to separate its functions into two distinct processes: a privileged one (with administrative rights) and an unprivileged one (without administrative rights). This architecture minimizes the risk that vulnerabilities in the SSH daemon can be exploited to gain root access.

Why the Directory Matters

The message regarding the missing privilege separation directory typically means that the directory where the SSH daemon is supposed to create runtime files does not exist. The run/sshd directory is used by the SSH daemon to store PID files and other important runtime information related to the SSH process.

Common Causes of the Missing Directory Error

Directory Deletion: The /run/sshd directory may have been deleted either accidentally or during a system cleanup.
Improper Configuration: If the sshd_config file has been improperly configured, it may not point to the correct path.
Permissions Issues: The directory may exist, but the sshd process does not have the necessary permissions to access it.

How to Fix the Issue

If you encounter the "missing privilege separation directory" error, here are the steps to resolve it:

Step 1: Check Directory Existence

First, check if the /run/sshd directory exists by running the following command:

ls -ld /run/sshd

If the directory does not exist, you will see an error message.

Step 2: Create the Directory

If the directory is missing, create it with the following command:

sudo mkdir /run/sshd

Step 3: Set the Correct Permissions

Next, ensure that the sshd process can access this directory by setting the correct ownership and permissions:

sudo chown root:root /run/sshd
sudo chmod 755 /run/sshd

Step 4: Restart the SSH Daemon

After creating the directory and setting permissions, restart the SSH daemon to apply the changes:

sudo systemctl restart sshd

Best Practices for SSH Configuration

In addition to resolving the missing privilege separation directory error, consider implementing these best practices for SSH security:

Use SSH Key Authentication: Instead of passwords, use SSH keys for authentication to enhance security.
Disable Root Login: Edit the sshd_config file and set PermitRootLogin no to prevent root logins over SSH.
Limit User Logins: Specify allowed users with the AllowUsers directive in sshd_config.
Use a Non-Standard Port: Change the default SSH port (22) to a non-standard port to reduce the likelihood of automated attacks.
Regular Updates: Keep your SSH server and all related software up to date to avoid security vulnerabilities.

Conclusion

The "missing privilege separation directory: run/sshd" warning is a common issue that can arise when configuring SSH. By understanding the underlying principles of privilege separation, checking the necessary directories, and implementing best security practices, you can ensure your SSH server remains secure and functional. If you're new to managing SSH, following these steps will not only help you resolve this error but also improve your overall server security posture.

For further reading, always refer to the official OpenSSH documentation and community forums for updates and troubleshooting tips.

Attribution

This content is based on discussions and knowledge derived from GitHub's community forums where users frequently address similar issues regarding SSH configuration.