删除现有规则

  1. iptables -F

设置默认的chain策略

  1. iptables -P INPUT DROP
  2. iptables -P FORWARD DROP
  3. iptables -P OUTPUT DROP

允许全部进来的SSH

  1. iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

iptables操作 - 图1

只允许某个特定网络进来的SSH

  1. iptables -A INPUT -i eth0 -p tcp -s 192.168.1.2 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

允许进来的HTTP

  1. iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A OUTPUT -o eth0 -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT

多端口（SSH,HTTP,HTTPS）

  1. iptables -A INPUT -i eth0 -p tcp -m multiport --dports 22,80,443 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A OUTPUT -o eth0 -p tcp -m multiport --sports 22,80,443 -m state --state ESTABLISHED -j ACCEPT

允许出去的SSH

  1. iptables -A OUTPUT-o eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A input -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

允许外出的SSH，但仅访问某个特定的网络

  1. iptables -A OUTPUT-o eth0 -p tcp -d 192.168.1.0/24 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A input -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT 1

允许外出的HTTPS

  1. iptables -A OUTPUT-o eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A input -i eth0 -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT

对进来的HTTPS流量做负载均衡

  1. iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 0 -j DNAT --to-destination 192.168.1.101:443
  2. iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 1 -j DNAT --to-destination 192.168.1.102:443
  3. iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 2 -j DNAT --to-destination 192.168.1.103:443

从内部向外部PING

  1. iptables -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT
  2. iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT

从外部向内部PING

  1. iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
  2. iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT

允许环回（lookback）访问

  1. iptables -A INPUT -i lo -j ACCEPT
  2. iptables -A OUTPUT -i lo -j ACCEPT

允许packets从内网访问外网

  1. iptables -A FORWARD -i eth0 -o eth1 -j ACCEPT

允许外出的DNS

  1. iptables -A OUTPUT -p udp -o eth0 --dport 53 -j ACCEPT
  2. iptables -A INPUT -p udp -i eth0 --sport 53 -j ACCEPT

允许某个特定网络rsyncj进入本机

  1. iptables -A INPUT -i eth0 -p tcp -s 192.168.1.0/24 --dport 873 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A OUTPUT -o eth0 -p tcp --sport 873 -m state --state ESTABLISHED -j ACCEPT

允许某个特定网络的MYSQL连接

  1. iptables -A INPUT -i eth0 -p tcp -s 192.168.1.0/24 --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A OUTPUT -o eth0 -p tcp --sport 3306 -m state --state ESTABLISHED -j ACCEPT

允许sendmail或postfix

  1. iptables -A INPUT -i eth0 -p tcp  --dport 25 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A OUTPUT -o eth0 -p tcp --sport 25 -m state --state ESTABLISHED -j ACCEPT

允许IMAP和IMAPS

  1. iptables -A INPUT -i eth0 -p tcp  --dport 143-m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A OUTPUT -o eth0 -p tcp --sport 143 -m state --state ESTABLISHED -j ACCEPT
  3. iptables -A INPUT -i eth0 -p tcp  --dport 993 m state --state NEW,ESTABLISHED -j ACCEPT
  4. iptables -A OUTPUT -o eth0 -p tcp --sport 993 -m state --state ESTABLISHED -j ACCEPT

允许POP3和POP3S

  1. iptables -A INPUT -i eth0 -p tcp  --dport 110 -m state --state NEW,ESTABLISHED -j ACCEPT
  2. iptables -A OUTPUT -o eth0 -p tcp --sport 110 -m state --state ESTABLISHED -j ACCEPT
  3. iptables -A INPUT -i eth0 -p tcp  --dport 995 -m state --state NEW,ESTABLISHED -j ACCEPT
  4. iptables -A OUTPUT -o eth0 -p tcp --sport 995 -m state --state ESTABLISHED -j ACCEPT

防止DOS攻击

  1. iptables -A INPUT -p tcp --dport 80 -m limit --limit 25/minute --limit-burst 100 -j ACCEPT

设置442端口转发到22端口

  1. iptables -t nat -A PREROUTING -p tcp -d 192.168.1.100  --dport 442 -j DNAT --to 192.168.1.100:22
  2. iptables -A INPUT -i eth0 -p tcp --dport 442 -m state --state NEW,ESTABLISHED -j ACCEPT
  3. iptables -A OUTPUT -o eth0 -p tcp --sport 442 -m state --state ESTABLISHED -j ACCEPT

为丢弃的包做日志LOG

  1. iptables -N LOGGING
  2. iptables -A INPUT -j LOGGING
  3. iptables -A LOGGING -m limit --limit 2/min -j LOG --log-prefix "Iptables Packets Dropped" --log-level 7
  4. iptables -A LOGGING -j DROP