How to use PuTTY or similar SSH client to check your server health

For Mac/Linux user, you don’t need to install a SSH client. Just open your Terminal window and you are good to SSH to your server.

For Windows user, PuTTY is a free and safe software application which can be used to make an SSH connection to your server. You can download the application at http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html.

How to use PuTTY or similar SSH client to check your server health?

Command:  # top

Usage: Check the node to make sure that no single process is consuming all of the available memory.

Check the physical free memory of the system and whether the SWAP free memory meets the requirements.

Output:

The screen lists the 15 most active processes that are currently running on the node.

For a single process, the CPU usage should be less than 40%. The total CPU usage should be less than 70%.

The memory utilization (real – free)/real should be less than 70%.

 

Command: # df –h

Usage: Check free space of the system hard disk.

Output:

The usage of the file system space should be less than 80%.

 

Command: # ntpq -p

Usage: Check this file for error messages

Output: 

A table of system clocks appears. The line representing the system clock currently used by the node is marked with an asterisk (*).

 

Command: # ps -ef

Usage:  Check which processes are running on the server, which user started the process (UID), process ID (PID), and the command that started the process (CMD).

Output: 

A list of all processes currently running on the system. The PID is important when you wish to “kill” the process, and the CMD is used to start the process again

 

Command: # ps -aux

Usage:  Similar to “ps -ef” it shows up which TCP connection the server is connecting to

Output: 

A list of all processes and connections currently running on the system.

 

Command: # netstat -plan | grep :80 | wc -l

Usage:  View the current concurrent users

Output: 

The number of the current concurrent users

Conclusion

SSH is handy when you need to troubleshoot or monitor your server. You can be a SSH guru too practice more and play around with ssh commands on your server.

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