How do i use nmap to scan only 100 ports?

  • Man page for nmap

    Quote from the nmap man page:

    While Nmap is commonly used for security audits, many systems and network administrators find it useful for routine tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime.

    -F (Fast (limited port) scan) .
    	   Specifies that you wish to scan fewer ports than the default. Normally Nmap scans the most
    	   common 1,000 ports for each scanned protocol. With -F, this is reduced to 100.
    	   Nmap needs an nmap-services file with frequency information in order to know which ports are
    	   the most common. If port frequency information isn't available, perhaps because of the use of
    	   a custom nmap-services file, Nmap scans all named ports plus ports 1-1024. In that case, -F
    	   means to scan only ports that are named in the services file.

    This is also called a fast scan or limited scan.

    $ nmap -F localhost
    Starting Nmap 6.40 ( ) at 2017-03-12 09:34 BST
    Nmap scan report for localhost (
    Host is up (0.0013s latency).
    Other addresses for localhost (not scanned):
    Not shown: 96 closed ports
    22/tcp  open  ssh
    25/tcp  open  smtp
    111/tcp open  rpcbind
    631/tcp open  ipp
    Nmap done: 1 IP address (1 host up) scanned in 0.03 seconds

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