1、檢查是否有安裝iptables, 我是在root賬號下執行的，如果非root有些請加上sudo
# 檢查
root@cocosum:~# which iptables
/sbin/iptables
root@cocosum:~# whereis iptables
iptables: /sbin/iptables /etc/iptables /usr/share/iptables /usr/share/man/man8/iptables.8.gz
# 說明有安裝iptables
2、如果沒有安裝iptables則需要安裝
# 進行安裝
sudo apt-get install iptables
3、如果安裝了需要配置防火牆規則，我這裏自己創建一個防火牆規則
# 創建防火牆規則的文件
root@cocosum:~# vi /etc/iptables
# 添加下面的規則
*filter
:INPUT DROP [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:syn-flood - [0:0]
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 443 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 3306 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 8080 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 7070 -j ACCEPT
-A INPUT -p icmp -m limit --limit 100/sec --limit-burst 100 -j ACCEPT
-A INPUT -p icmp -m limit --limit 1/s --limit-burst 10 -j ACCEPT
-A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -j syn-flood
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A syn-flood -p tcp -m limit --limit 3/sec --limit-burst 6 -j RETURN
-A syn-flood -j REJECT --reject-with icmp-port-unreachable
COMMIT
4、保存規則
root@cocosum:~# iptables-save > /etc/iptables
5、創建一個腳本, 爲了每次重啓系統, iptables防火牆自動啓動
# 直接創建，目的是爲了系統每次重啓自動加載
root@cocosum:~# vi /etc/network/if-pre-up.d/iptables
# 內容
#!/bin/bash
iptables-restore < /etc/iptables
# :wq保存
6、給添加的腳本有執行的權限
root@cocosum:~# chmod +x /etc/network/if-pre-up.d/iptables
7、查看iptables；直接iptables -L ，和centos 差不多
root@cocosum:~# iptables -L
Chain INPUT (policy DROP)
target prot opt source destination
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:ssh
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:http
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:https
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:mysql
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:http-alt
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:7070
ACCEPT icmp -- anywhere anywhere limit: avg 100/sec burst 100
ACCEPT icmp -- anywhere anywhere limit: avg 1/sec burst 10
syn-flood tcp -- anywhere anywhere tcp flags:FIN,SYN,RST,ACK/SYN
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain syn-flood (1 references)
target prot opt source destination
RETURN tcp -- anywhere anywhere limit: avg 3/sec burst 6
REJECT all -- anywhere anywhere reject-with icmp-port-unreachable