Measure the test taker's knowledge about how to set up a firewall in a Linux operating system.

Article Title: describes how to set up a firewall in a Linux operating system. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.

To modify the firewall configuration, You need to modify the/etc/sysconfig/iptables file. If you want to open a port, add one in it.

-A RH-Firewall-1-INPUT-m state -- state NEW-m tcp-p tcp -- dport 1521-j ACCEPT

1521 indicates the port number to be opened, and then restart the Firewall Service in linux.

Command to stop/start the Firewall Service:

Run

Service iptables stop -- stop

Service iptables start -- start

(The service command is located in/sbin)

Firewall Rules can be activated only when the iptables service is running. To manually start the service, run the following command:

/Sbin rvice iptables restart

To ensure that it is started during system boot, run the following command:

/Sbin/chkconfig -- level 345 iptables on

The ipchains service cannot run with the iptables service at the same time. To disable the ipchains service, run the following command:

/Sbin/chkconfig -- level 345 ipchains off