Iptables (Linux Firewall)

1. install the software package

Use the ISO image in the virtual machine to install the corresponding software package

Rpm-q iptables (check whether this service is installed)

Ii. Start the linux Firewall

Service Startup Script:/etc/rc. d/sysconfig/iptables [srat/stop/retsart]

Service iptables restart

# System-config-securitylevel-tui (Firewall Configuration tool)

Iii. Related Documents

(1) configuration file:/etc/sysconfig/iptables-config

(2) side configuration file:/etc/sysconfig/iptablses (this file does not exist in the original system. You need to create a package for filtering and save the firewall policy, save the Command service iptables save service iptablse restart)

Iv. Operation object

(1) rule table: composed of Rule chains

Fileter (default): Packet Filtering

Nat: Address Translation

Mangles: Policy Routing

(2) Rule chain: composed of rules

(3) rule: the most basic setting item, used to Set firewall policies

5. iptables syntax Overview

BASIC script: iptabales-F (clear all packet filtering rules)

Iptablse-X (clear all data links)

Iptables-Z (counters are cleared)

Iptalbes-a input-I eth0-p tcp -- dport 80-j ACCEPT allows external machines to access the web of the server

Iptables-a input-I eht0-p tcp -- dport 22-j ACCEPT enable SSH access

Service iptablse save

Service iptabalse restart