Limiting Users' Traffic Usage in SSH: A Guide for Linux and Ubuntu

SSH (Secure Shell) is a widely used protocol that allows users to securely access and manage remote systems. However, it is important to manage and limit the traffic usage of SSH to ensure optimal performance and prevent any potential abuse. In this guide, we will explore how to limit users' traffic usage in SSH on Linux and Ubuntu systems.

Understanding SSH Traffic Usage

SSH traffic is measured in terms of data transferred between the client and server. This includes both the data sent from the client to the server (upload) and the data received from the server to the client (download). By limiting the traffic usage, you can control the amount of data transferred by each user.

Limiting SSH Traffic Usage

To limit SSH traffic usage, we will use the sshd_config file, which is the main configuration file for the SSH server. Follow the steps below:

1. Open the terminal on your Linux or Ubuntu system.
2. Enter the following command to open the sshd_config file:

This will open the sshd_config file in the nano text editor.

3. Scroll down to find the line that starts with #MaxSessions. Uncomment the line by removing the # at the beginning.
4. Change the value next to MaxSessions to the desired number of maximum SSH sessions per user. For example, if you want to limit each user to 5 SSH sessions, the line should look like:

5. Scroll down further to find the line that starts with #MaxDataSize. Uncomment the line by removing the #.
6. Change the value next to MaxDataSize to the desired data size limit in kilobytes (KB). For example, if you want to limit each user to 100MB of data transfer, the line should look like:

Note that the value is in kilobytes, so 100MB is equal to 100 * 1024 = 102400 KB.

7. Save the changes by pressing Ctrl + X, then Y, and finally Enter.
8. Restart the SSH service for the changes to take effect by entering the following command:

That's it! You have successfully limited the traffic usage for SSH on your Linux or Ubuntu system.

Conclusion

Limiting users' traffic usage in SSH is an important step to ensure optimal performance and prevent abuse. By following the steps outlined in this guide, you can easily set limits on the number of SSH sessions and data transfer for each user on your Linux or Ubuntu system.