#允许外网vpn连接 iptables -A INPUT -s 192.186.0.0/24 -p tcp -m state –state ESTABLISHED,RELATED -j ACCEPT iptables -A INPUT -i ppp0 -p tcp –syn -m connlimit –connlimit-above 15 -j DROP #为了防止DOS太多连接进来,那么可以允许最多15个初始连接,超过的丢弃 iptables -A INPUT -s 192.186.0.0/24 -p tcp –syn -m connlimit –connlimit-above 15