Port Security for Linux

The so-called Port security refers to the software program that can open port , not the port itself.

Services and port corresponding to the document /etc/services, commonly used to observe the port of the program has netstat and the Nmap .

Netstat: Monitor your Port with your own program on this machine

Nmap: Through the network detection software assistance, can detect other non-native network host

Common combinations of netstat options

-TUNL List of network services in the listener

-tun List Online status of a network

-TUNP * * * has been established or is in the monitoring of the online

Nmap(Network Exploration tool and security Port Scanner)

Nmap [ Scan type ] [ scan Parameters ] [hosts address and Range ]

[ Scan type ]

-st Scan TCP packets established online connetc ()

-ss Scan TCP packets with SYN -tagged data

-SP Scan in ping mode

-SU Scan in UDP packet Format

-s0 Host scan with IP Protocol

[ scan Parameters ]

-pt uses a ping scan in TCP to learn that several hosts are currently alive (common)

The-PL uses the actual Ping(with ICMP packets) to scan

-P Port range

[Hosts address and scope ]

There are several ways such as direct write, followed by mask, fuzzy match, specified range, etc.

(not to be continued--close unused port)