Server operation and maintenance work is meticulous living, usually a small security risk will lead to a catastrophic accident occurred. So security is a server maintenance is the most important part, the following is my finishing prevent hackers from port scanning methods, we have good ideas can be shared under: linux server using the built-in firewall function code is as follows: iptables -A INPUT -p tcp --tcp-flags ALL FIN, URG, PSH -j DROP iptables -A INPUT -p tcp --tcp-flags SYN, RST SYN, RST -j DROP iptables -A INPUT -p tcp --tcp- flags SYN, FIN SYN, FIN -j DROP usually we can also command -nltp to see our server who opened the port number netstat.
Reproduced in: https: //my.oschina.net/wzlee/blog/262203