Firstly, stop and mask the firewalld service: systemctl stop firewalld systemctl mask firewalld Then, install the iptables-services package: yum install iptables-services After that, enable the service at boot-time: systemctl enable iptables Managing the service; systemctl stop|start|restart iptables Saving your firewall rules can be done as follows: service iptables save

Edit the /etc/security/limits.conf file then set the limit for open files from 1024 to 65536. “username” hard nofiles 65536 “username” soft nofiles 65536

Linux swap space is normally configured either on a dedicated partition or a logical volume. Such space is used to extend the amount of effective RAM on a system, as virtual memory for currently running programs. But you can’t just buy extra RAM and eliminate swap space. Linux moves infrequently used programs and…

The following command will list all the files that were modified in the last two days under the current directory. find . -mtime -2 Resources : Linux 101 Hacks

The following command will list all the files that were modified more than 60 days ago under the current directory. find . -mtime +60 Resources : Linux 101 Hacks

In a Linux file system, it is very useful to be able to access a single file from different locations. This discourages you from copying a file to different locations, where subsequently different versions of the file may come to exist. In a Linux file system, you can use links for this purpose.…

• Monitoring your Linux system. • Data backup and creating snapshots. • Dumping Oracle or MySQL database for backup. • Creating email based alert system. • Find out what processes are eating up your system resources. • Find out available and free memory. • Find out all logged in users…