iptables -A INPUT -j ACCEPT -p tcp --dport 1352
iptables -A INPUT -p udp --destination-port 53 -j ACCEPT
# 在input规则中状态为：STATE RELATED 的包都接受
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
# 启用系统ip转发功能
echo 1 > /proc/sys/net/ipv4/ip_forward
< --end-- >
7.1.3 iptables实例2：
注：这个实例中，只需要设置tcp、udp端口和服务器网络段ip范围即可，其他已经默认设置好。
#!/bin/sh
# make:yongzhang
# time:2004-06-18
# e-mail: yongzhang@wiscom.com.cn
PATH=/sbin:/bin:/usr/sbin:/usr/bin
##tcp allow ports
TPORTS="80 22"
##udp allow ports
UPORTS="53"
##internal server_ip range
SERVER_IP="172.18.10.0/24"
##disable forwarding
echo 0 > /proc/sys/net/ipv4/ip_forward
##reset default policies
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT
iptables -t nat -P PREROUTING ACCEPT
iptables -t nat -P POSTROUTING ACCEPT
iptables -t nat -P OUTPUT ACCEPT
##del all iptables rules
iptables -F INPUT
iptables -F FORWARD
iptables -F OUTPUT
##clean all non-default chains
iptables -X
iptables -t nat -X
##iptables default rules
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT
##allow ping packets
iptables -A INPUT -p ICMP -s 0/0 --icmp-type 0 -j ACCEPT
iptables -A INPUT -p ICMP -s 0/0 --icmp-type 3 -j ACCEPT
iptables -A INPUT -p ICMP -s 0/0 --icmp-type 5 -j ACCEPT
iptables -A INPUT -p ICMP -s 0/0 --icmp-type 8 -j ACCEPT
iptables -A INPUT -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT
#iptables -A INPUT -p ICMP -s 0/0 --icmp-type 11 -m limit --limit 5/s -j ACCEPT
iptables -A FORWARD -p ICMP -j ACCEPT
##enable forwarding
iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
##STATE RELATED for router
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
##accept internal packets on the internal i/f
iptables -A INPUT -s $SERVER_IP -p tcp -j ACCEPT
##open ports on router for server/services
##TCP PORTS
for ATP in $TPORTS
do
iptables -A INPUT ! -s $SERVER_IP -d $SERVER_IP -p tcp --destination-port $ATP -j ACCEPT
iptables -A FORWARD -p tcp --destination-port $ATP -j ACCEPT
done
##UDP PORTS
for AUP in $UPORTS
do
iptables -A INPUT -p udp --destination-port $AUP -j ACCEPT
iptables -A FORWARD -p udp --destination-port $AUP -j ACCEPT
done
##bad_packets chain
##drop INVALID packets immediately
iptables -A INPUT -p ALL -m state --state INVALID -j DROP
