[O & M engineer _ 05] System Security Inspection tool-NMAP

Cui NIDI intruded into the energy management system of the power station using NMAP in US blockbusters and Besides hacking, rocky stealing, and NMAP are good choices for detecting the security of your server.
If someone else's host is sniffed and the IP address of the port may be recorded by TCP_WRAPPERS, this will be a legal action.

In addition, NMAP is well-learned and can be understood by interested users.

(I) Use default parameters to scan ports enabled on the local machine

 [root @ Rocky ~] # NMAP localhoststarting NMAP 6.25 (http://nmap.org) at cstnmap scan report for localhost (127.0.0.1) host is up (0.000025 s latency ). rdns record for 127.0.0.1: localhost. localdomainnot shown: 994 closed portsport state service22/tcp open ssh25/tcp open smtp111/tcp open rpcbind631/tcp open ipp3306/tcp open mysql5989/tcp open WBEM-httpsnmap done: 1 IP address (1 host up) scanned in 0.39 seconds 

there are 6 states:
① open: the port is open
② closed: the port is closed
③ filtered: the port is blocked by the firewall IDS/IPS and cannot be determined.
④ unfiltered: the port is not blocked, but whether the port is open must be further determined
⑤ open | filtered: The port is open or blocked
⑥ closed | filtered: port is disabled or blocked
(ii) Analysis of TCP/UDP protocol
NMAP-Stu localhost
BR> (3) obtain the active hosts in the working environment
NMAP-SP 192.168.1. *