Use iptables to prevent phpddos from sending packets externally

Recently, php-ddos flood, many web hosting service providers worry that their websites are implanted with php-ddos due to website permissions or vulnerabilities, and a large number of data packets are sent externally, this will cause unnecessary troubles and losses. To this end, we can use iptables to prohibit external packet sending from the root cause of php-ddos. 1. Prohibit the local computer from sending UDP packets to the outside. iptables-a output-p udp-j DROP. 2. Allow ports that require UDP services (such as DNS) iptables-I OUTPUT-p udp -- dport 53-d 8.8.8.8-j ACCEPT Green "53", which is the UDP port required by DNS. The yellow "8.8.8.8" section is the DNS IP address, depending on the settings of your server, if you do not know the dns ip address used by your server, you can run the following command in SSH to obtain: cat/etc/resolv. conf | grepnameserver | awk 'nr = 1 {print $2 }'