Question – I need to check whether SSH (sshd) is running on my Linux machine. I have a Debian Linux distribution. How can I tell if my OpenSSH server is running?
Using ss command. Ss is used to dump socket statistics. It allows showing. Rebex SSH Check is a testing tool for SSH servers accessible over internet. The report contains an overview of SSH configuration of the server as well as security recommendations. The service is free.
Check Ssh Service On Linux
There are several ways to check whether SSH is running. The sshd daemon is the process that runs the OpenSSH ssh server.
First Check if the process sshd is running:
This will output something like the following if it finds the process called sshd:
So sshd is running with process ID 1399! It is indeed running!
Second, check if the process sshd is listening on port 22:
If ssh is listening on port 22, you will get the following:
Check Ssh Service Centos
So the process with ID 1399 (sshd) is listening on port 22! The second test passed!
Third, you can use the lsof command to check if the port 22 TCP file is open:
So sshd (SSH daemon) and httpd (Apache web server daemon) are both running and listening on the ssh and http ports respectively! Third test passed.
Four, try to telnet to port 22:
If the port is open, you will get the following output:
If the port number 22 is not open, you will get the following:
Five, check the status of the sshd service:
If you use CentOS or Red Hat:
If you use Debian or Ubuntu (or CentOS or RedHat):
So these were five interesting methods in which you could check if the SSH OpenSSH server is running and listening on port 22. If the process sshd is misbehaving or not listening on port 22, one of these methods will surely fail and you should start or restart sshd using the following command: