Tag Archives: ssh

Safeguarding Your SSH Configurations with ssh-audit

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In the vast ocean of network security, SSH (Secure Shell) stands as a towering lighthouse guarding the data traffic to and from your servers. However, how do you ensure that this lighthouse is in optimal condition? Enter ssh-audit, a tool for auditing your SSH server and client configurations.

Ssh-audit supports SSH1 and SSH2 protocol servers, diving deep into the SSH configurations to grab banners, recognize the software and operating systems involved, and even detect compression settings. It gathers information on key exchanges, host keys, encryption, and message authentication code algorithms, providing a comprehensive report on their status.

Getting started with ssh-audit is a breeze. Clone the repository from GitHub, and with a few commands in your terminal, you’re on your way to auditing your SSH configurations. The tool fetches algorithm information, outputting details such as availability, removal or disabling status, and security strength (unsafe, weak, legacy, etc). Moreover, it provides algorithm recommendations based on the recognized software version, aligning your settings with industry standards.

The icing on the cake? Ssh-audit outputs security information, including related issues and assigned CVE (Common Vulnerabilities and Exposures) list, offering you a clear picture of the security posture of your SSH setups.

With ssh-audit, not only do you get to audit your SSH configurations, but you also receive actionable insights to harden your SSH setups against potential threats. So, the next time you’re looking to bolster your network security, try ssh-audit and sail smoothly in the turbulent waters of cyber threats.

Note that MSI has no relationship with the tool or the authors. We just found the tool useful for infosec teams.

 * Just to let you know, we used some AI tools to gather the information for this article, and we polished it up with Grammarly to make sure it reads just right!

How to Rotate Your SSH Keys

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SSH keys are used to secure access to and authenticate authorized users to remote servers. They are stored locally on the client machine and are encrypted using public-key cryptography. These keys are used to encrypt communications between the client and server and provide secure remote access.

When you log into a remote machine, you must provide a valid private key to decrypt the traffic. As long as the private key remains secret, only you can access the server. However, if someone obtains your private key, they can impersonate you on the network.

SSH key rotation helps prevent this type of unauthorized access. It reduces the risk that someone has access to your private key, and helps prevent malicious users from being able to impersonate you on your network.

Most security policies and best practices call for rotating your key files on a periodic basis, ranging from yearly to quarterly, depending on the sensitivity of the data on the system. Such policies go a long way to ensuring the security of authentication credentials and the authentication process for sensitive machines.

There are two ways to rotate your keys: manually, and automatically.

Manually

To manually perform key rotation, you need to generate a new pair of keys. Each time you do this, you create a new key pair. You then upload the public key file to the server you wish to connect to. Once uploaded, the server uses the public key to verify that you are who you say you are.

Automatically

An alternative approach is to use automatic key rotation. With automatic rotation, you don’t need to generate a new key pair each time you change your password. Instead, you simply update the permissions on your existing key file.

The following steps show how to configure automatic rotation.

1. Generate a new keypair

2. Upload the public key to the remote server

3. Configure the remote server to use the new keypair

4. Update the permissions on the old keypair file

5. Delete the old keypair

6. Logout from the remote server

More Information

On Linux systems, use the “man” command to learn more about the following:

    • ssh-keygen command
    • ssh-public-key command
    • upload-ssh-public-key command

The examples should provide options for command parameters and sample command output for your operating system.

For more information about the SSH protocol, you can review the Wikipedia article here.