本文檔詳細介紹生產環境中超級實用的iptables腳本。
創建 iptables.sh 腳本
[root@Jaking ~]# vim iptables.sh
#!/bin/bash
#清空 filter 表和 nat 表
iptables -F
iptables -t nat -F
#關掉 firewalld
systemctl stop firewalld &>/dev/null
systemctl disable firewalld &>/dev/null
#以下兩行允許某些調用 localhost 的應用訪問
iptables -A INPUT -i lo -j ACCEPT #規則1
iptables -A INPUT -s 127.0.0.1 -d 127.0.0.1 -j ACCEPT #規則2
#以下一行允許從其他地方 ping
iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT #規則3
#以下一行允許從其他主機、網絡設備發送 MTU 調整的報文
#在一些情況下，例如通過 IPSec VPN 隧道時，主機的 MTU 需要動態減小
iptables -A INPUT -p icmp --icmp-type fragmentation-needed -j ACCEPT #規則4
#以下兩行分別允許所有來源訪問 TCP 80,443 端口
iptables -A INPUT -p tcp --dport 80 -j ACCEPT #規則5
iptables -A INPUT -p tcp --dport 443 -j ACCEPT #規則6
#以下一行允許所有來源訪問 UDP 80,443 端口
iptables -A INPUT -p udp -m multiport --dports 80,443 -j ACCEPT #規則7
#以下一行允許 192.168.1.63 來源的 IP 訪問 TCP 22 端口(OpenSSH)
iptables -A INPUT -p tcp -s 192.168.1.63 --dport 22 -j ACCEPT #規則8
#以下一行允許 192.168.1.3(發起SSH連接的系統對應網卡的IP) 來源的 IP 訪問 TCP 22 端口(OpenSSH)
#如果是在遠程終端跑本腳本，最好開啟以下一行以防被踢掉
#另一種更加簡便的方式：iptables -I INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -p tcp -s 192.168.1.3 --dport 22 -j ACCEPT #規則9
#以下一行允許 192.168.1.26 來源的 IP 訪問 UDP 161 端口(SNMP)
iptables -A INPUT -p udp -s 192.168.1.26 --dport 161 -j ACCEPT #規則10
#配置 NAT
#啟用內核路由轉發功能
echo 1 > /proc/sys/net/ipv4/ip_forward
echo "net.ipv4.ip_forward = 1" > /etc/sysctl.conf
sysctl -p &>/dev/null
#配置源地址轉換 SNAT
#將 192.168.2.0/24 轉換成 192.168.1.63
iptables -t nat -A POSTROUTING -s 192.168.2.0/24 -j SNAT --to 192.168.1.63 #規則11
#配置目的地址轉換 DNAT
#將 192.168.1.63 的 80 端口請求轉發到 192.168.2.2 的 80 端口
iptables -t nat -A PREROUTING -d 192.168.1.63 -p tcp --dport 80 -j DNAT --to 192.168.2.2:80 #規則12
#以下一行禁止所有其他的進入流量
iptables -A INPUT -j DROP #規則13
#以下一行允許本機響應規則編號為 1-12 的數據包發出
iptables -A OUTPUT -m state --state ESTABLISHED -j ACCEPT #規則14
#以下一行禁止本機主動發出外部連接
iptables -A OUTPUT -j DROP #規則15
#以下一行禁止本機轉發數據包
iptables -A FORWARD -j DROP #規則16
#固化 iptables
iptables-save > /etc/sysconfig/iptables
[root@Jaking ~]# chmod 755 iptables.sh
測試
[root@Jaking ~]# ./iptables.sh
[root@Jaking ~]#
[root@Jaking ~]#
[root@Jaking ~]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere
ACCEPT all -- localhost localhost
ACCEPT icmp -- anywhere anywhere icmp echo-request
ACCEPT icmp -- anywhere anywhere icmp fragmentation-needed
ACCEPT tcp -- anywhere anywhere tcp dpt:http
ACCEPT tcp -- anywhere anywhere tcp dpt:https
ACCEPT udp -- anywhere anywhere multiport dports http,https
ACCEPT tcp -- 192.168.1.63 anywhere tcp dpt:ssh
ACCEPT tcp -- 192.168.1.3 anywhere tcp dpt:ssh
ACCEPT udp -- 192.168.1.26 anywhere udp dpt:snmp
DROP all -- anywhere anywhere
Chain FORWARD (policy ACCEPT)
target prot opt source destination
DROP all -- anywhere anywhere
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere state ESTABLISHED
DROP all -- anywhere anywhere
[root@Jaking ~]# iptables -L --line-number
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT all -- anywhere anywhere
2 ACCEPT all -- localhost localhost
3 ACCEPT icmp -- anywhere anywhere icmp echo-request
4 ACCEPT icmp -- anywhere anywhere icmp fragmentation-needed
5 ACCEPT tcp -- anywhere anywhere tcp dpt:http
6 ACCEPT tcp -- anywhere anywhere tcp dpt:https
7 ACCEPT udp -- anywhere anywhere multiport dports http,https
8 ACCEPT tcp -- 192.168.1.63 anywhere tcp dpt:ssh
9 ACCEPT tcp -- 192.168.1.3 anywhere tcp dpt:ssh
10 ACCEPT udp -- 192.168.1.26 anywhere udp dpt:snmp
11 DROP all -- anywhere anywhere
Chain FORWARD (policy ACCEPT)
num target prot opt source destination
1 DROP all -- anywhere anywhere
Chain OUTPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT all -- anywhere anywhere state ESTABLISHED
2 DROP all -- anywhere anywhere
[root@Jaking ~]# iptables -t nat -L
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
DNAT tcp -- anywhere 192.168.1.63 tcp dpt:http to:192.168.2.2:80
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
SNAT all -- 192.168.2.0/24 anywhere to:192.168.1.63
[root@Jaking ~]# iptables -t nat -L --line-number
Chain PREROUTING (policy ACCEPT)
num target prot opt source destination
1 DNAT tcp -- anywhere 192.168.1.63 tcp dpt:http to:192.168.2.2:80
Chain INPUT (policy ACCEPT)
num target prot opt source destination
Chain OUTPUT (policy ACCEPT)
num target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
num target prot opt source destination
1 SNAT all -- 192.168.2.0/24 anywhere to:192.168.1.63
iptables 的清空和恢復
[root@Jaking ~]# iptables -F
[root@Jaking ~]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
[root@Jaking ~]# iptables -t nat -F
[root@Jaking ~]# iptables -t nat -L
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
[root@Jaking ~]# iptables-restore < /etc/sysconfig/iptables
[root@Jaking ~]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere
ACCEPT all -- localhost localhost
ACCEPT icmp -- anywhere anywhere icmp echo-request
ACCEPT icmp -- anywhere anywhere icmp fragmentation-needed
ACCEPT tcp -- anywhere anywhere tcp dpt:http
ACCEPT tcp -- anywhere anywhere tcp dpt:https
ACCEPT udp -- anywhere anywhere multiport dports http,https
ACCEPT tcp -- 192.168.1.63 anywhere tcp dpt:ssh
ACCEPT tcp -- 192.168.1.3 anywhere tcp dpt:ssh
ACCEPT udp -- 192.168.1.26 anywhere udp dpt:snmp
DROP all -- anywhere anywhere
Chain FORWARD (policy ACCEPT)
target prot opt source destination
DROP all -- anywhere anywhere
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere state ESTABLISHED
DROP all -- anywhere anywhere
[root@Jaking ~]# iptables -t nat -L
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
DNAT tcp -- anywhere 192.168.1.63 tcp dpt:http to:192.168.2.2:80
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
SNAT all -- 192.168.2.0/24 anywhere to:192.168.1.63
總結
以上就是生產環境中超級實用的iptables腳本，這個腳本可以直接拿去用，不過請謹慎操作！
本文原創地址：https://www.linuxprobe.com/super-practical-iptables.html編輯：傳棋，審核員：逄增寶
