To monitor system behavior, you need to start by creating a baseline that represents normal system behavior. You can do this using a tool like the sar command. You can then use tools such as netstat, iostat, lsof, w and uptime to monitor system behavior, comparing the results to the baseline to determine whether the system is experiencing problems. netstat -g // to display information about IPv4 and IPv6 multicast group membership -i // to return information,including specific property values, for all connected network devices -r // to display information about kernel routing tables -s // to list a summary of statistics for each networking protocol -p // to list which processes are using which ports -t // to return details only for connections that use TCP Note: netstat -r has been replaced by route -e ...

Capacity planning involves predicting what the capacity requirements for a system will be in future, and planning how to meet these requirements. Monitoring system resource use is important for capacity planning, because it establishes whether existing resource use is approaching capacity limits. In Linux you can use a range of tools to monitor system resource use. These include the top, ps, pstree, vmstat, sar and free commands. top -a // sort processes by allocated memory -b // batch mode -> send output to a file or another program -n // specify the number of times that top should run before exiting -p // pid or ID ps Unlike for the top command, output from the ps command does not refresh dynamically. ...

How to change the grey background on lock screen in Elementary OS Below there is a better explanation from Eric Melo. Thanks Eric for this video!

Access Control List in Linux How to use Access Control List in Linux terminal to set permissions.

How to Lock and Unlock User in Linux How do you lock a user account in Linux? Even more importantly, how do you unlock the user in Linux? Learn various ways of locking and unlocking users in Linux command line.

Kevin Mitnick talks about security in IT

The mind behind Linux – Linus Torvalds – TED

China’s Web Junkies: Internet Addiction Documentary Source: https://www.nytimes.com/2014/01/20/opinion/chinas-web-junkies.html

Managing special permissions and sticky bit in Linux.

There will be time for a tutorial on how to install mod_security for apache, and perhaps someday for nginx. Today I will explain how to add rules for yourself in the whitelist.conf file so that mod_security does not block WordPress functionality. After logging in via ssh to the server, type in the command: 1 sudo tail -f /var/log/httpd/error_log This is the log for Apache in Centos specified in the httpd.conf file, which you can find with the command: ...