Iptables common commands

# Flush all policyiptables-Fiptables-Xiptables-Ziptables-t nat-Fiptables-t nat-Xiptables-t nat-Ziptables-S INPUT # View chain policies The default is filter table # Enable ip forwardecho "1" > / proc/sys/net/ipv4/ip_forward# modulemodprobe ip_conntrack_ftpmodprobe ip_conntrack_tftpmodprobe ip_nat_ftpmodprobe ip_nat_tftp # # Default policyiptables-P INPUT DROPiptables-P OUTPUT DROPiptables-P FORWARD ACCEPT# Enable lo interfaceiptables-An INPUT-I lo-j ACCEPTiptables-An OUTPUT-o lo-j ACCEPT# DNS lookupiptables-An OUTPUT-o eth0-p udp-- dport 53-j ACCEPTiptables-An INPUT-I eth0-p udp-sport 53-j ACCEPT# SSH Serveriptables-An INPUT-s 192.168.0 ACCEPT# SSH Serveriptables 24-p tcp-- dport 22-j ACCEPTiptables-An OUTPUT-d 192.168.0 OUTPUT 24-p tcp-- sport 22-j ACCEPT# SSH clientiptables-An OUTPUT-d 192.168.0 sport 24-p tcp-- dport 22-j ACCEPTiptables-An INPUT-s 192.168.0.0Universe 24-p tcp-- sport 22-j ACCEPT# icmp requestiptables-An INPUT-s 192.168.0.0 -p icmp--icmp-type 8-j ACCEPTiptables-An OUTPUT-d 192.168.0.0Universe 24-p icmp--icmp-type 0-j ACCEPT# icmp echoiptables-An OUTPUT-d 192.168.0.0q24-p icmp--icmp-type 8-j ACCEPTiptables-An INPUT-s 192.168.0.0q24-p icmp--icmp-type 0-j ACCEPT# FTP serveriptables-An INPUT-s 192.168.0.0max 24-p tcp-- dport 21-j ACCEPTiptables -An OUTPUT-d 192.168.0.0 sport 24-p tcp-- sport 21-j ACCEPTiptables-An INPUT-m state-- state RELATED ESTABLISHED-j ACCEPTiptables-An OUTPUT-m state-- state RELATED,ESTABLISHED-j ACCEPT# SNATiptables-t nat-A POSTROUTING-s 192.168.0.0 DNATiptables-t nat-A PREROUTING-s 192.168.0.0Compact 24-j SNAT-- to-source 1.2.3.Compact 24-p tcp-- dport 80-j DNAT-- to-dest 192.168.0.254