Realtime Interview Questions asked from 3-5 years of Linux Admins Linux interview Question asked What is port no of SSH? 22 What is main configuration file of SSH? How to change Port no. of SSH? How to Block SSH access for a single user? What are the type of files in linux OS? ( regular -, d What is the difference between file and directory? How to check free space on Linux OS? Who to check size of files and folders on a server? How to check open ports on a server? How to check open ports on a remote server without login? What is difference between public and private IP address?