Linux under the firewall iptables learning notes

First, the opening and closing of the iptables

1. Reboot system effective

[Sun@webserver2 ~]$ sudo chkconfig iptables on
[Sun@webserver2 ~]$ sudo chkconfig iptables off

2. Immediate effect, reboot system failure

[Sun@webserver2 ~]$ sudo service iptables start
[Sun@webserver2 ~]$ sudo service iptables stop shutdown

Second, view iptables configuration

[Sun@webserver2 ~]$ sudo iptables-l-n

Third, open the specified port

Restart Iptables service in effect after each modification

1. Allow local loopback interface (that is, run native access to this computer)
1
[Sun@webserver2 ~]$ sudo iptables-a input-s 127.0.0.1-d 127.0.0.1-j ACCEPT

2. Allow access to 80 ports (Web server common port)

[Sun@webserver2 ~]$ sudo iptables-a input-p tcp--dport 80-j ACCEPT

3. Allow access to 22 ports (SSH port)

[Sun@webserver2 ~]$ sudo iptables-a input-p tcp--dport 22-j ACCEPT

4. Allow access to 3306 ports (MySQL port)

[Sun@webserver2 ~]$ sudo iptables-a input-p tcp--dport 3306-j ACCEPT

5. Allow access to Ports 21 and 20 (FTP server port)

[Sun@webserver2 ~]$ sudo iptables-a input-p tcp--dport 20-j ACCEPT
[Sun@webserver2 ~]$ sudo iptables-a input-p tcp--dport 21-j ACCEPT

6. Allow all native access to the outside

[Sun@webserver2 ~]$ sudo iptables-a output-j ACCEPT

Four, shielding IP

Restart Iptables service in effect after each modification

1. Block single IP

[Sun@webserver2 ~]$ sudo iptables-i input-s 123.45.6.7-j DROP

2. Shielding from 123.0.0.1 to 123.255.255.254 network segment

[Sun@webserver2 ~]$ sudo iptables-i input-s 123.0.0.0/8-j DROP

3. Shielding from 123.1.0.1 to 123.1.255.254 network segment

[Sun@webserver2 ~]$ sudo iptables-i input-s 123.1.0.0/16-j DROP

4. Shielding from 123.1.2.1 to 123.1.2.254 network segment

[Sun@webserver2 ~]$ sudo iptables-i input-s 123.1.2.0/24-j DROP

V. Delete Iptables rules that have been added
Restart Iptables service in effect after each modification

1. Display all iptables in serial number

[Sun@webserver2 ~]$ sudo iptables-l-n--line-numbers

2. Execute Delete serial number 1

1
[Sun@webserver2 ~]$ sudo iptables-d INPUT 1