In this tutorial, we will take a look at the SSH configuration administered by the sshd_config file. Modifying the sshd_config file permits us to modify how SSH connections play out on the server.
Before we proceed, ensure you have:
- SSH installed and running on your server
- Root or a sudo account.
With the above requirements met, we can proceed.
The OpenSSH Daemon Configuration
The ssh daemon (sshd) reads the configuration file located in /etc/ssh/sshd_config. However, you can override the default configuration by specifying the -f <filename> in the command line when starting the SSH daemon.
Entries in the configuration file are in the form of key-argument pairs with one entry per line. If a line in the configuration file begins with a #, SSH treats the entry as a comment and ignores it.
Keywords in the sshd configuration files and case-insensitive while the arguments are case-sensitive.
Changing SSH Daemon MaxSessions Settings
The MaxSessiosn setting defines the maximum number of open sessions per connection. A more precise way to think about this setting is, it allows you to control the number of SSH sessions sent over a single TCP connection. The default value is 10. The MaxSessions setting is very straightforward. The lower the number, the fewer number of connections and vice versa.
NOTE: Setting the value to 0 disables all sessions, including login, shell, and subsystem. To disable shell multiplexing, you can set the value to 1.
Edit the sshd_config file to change the MaxSessions to your desired value.
Uncomment and change the value.
That is all for MaxSessions in SSH.
NOTE: Before changing the setting, ensure you do not need more sessions than allowed in the config file.
Thank you for reading, and Happy SSH time!