Ubuntu Server - Using NMAP to scan your server for vulnerabilities.

From LinodeWiki

There may be other ways to install and configure this, but this is how I did it!

First install ubuntu, if you are not logged in as root you may need to add “sudo” in front of your command.

    apt-get update
    apt-get upgrade
    apt-get install nmap

Now here is an example of scanning ports randomized (-r) with verbose output (-v) and os detection (-O) for further enumeration/scanning.

    nmap -r -v -O putyourdomainhere.com

You should see output similar to this:

    Starting Nmap 4.62 ( http://nmap.org ) at 2008-12-08 12:18 EST
    Initiating Parallel DNS resolution of 1 host. at 12:18
    Completed Parallel DNS resolution of 1 host. at 12:18, 0.04s elapsed
    Initiating SYN Stealth Scan at 12:18
    Scanning putyourdomainhere.com (xx.xxx.xx.xx) [1715 ports]
    Discovered open port 80/tcp on xx.xxx.xx.xx
    Completed SYN Stealth Scan at 12:18, 0.05s elapsed (1715 total ports)
    Initiating OS detection (try #1) against putyourdomainhere.com (xx.xxx.xx.xx)
    Host putyourdomainhere.com (xx.xxx.xx.xx) appears to be up ... good.
    Interesting ports on putyourdomainhere.com (xx.xxx.xx.xx):
    Not shown: 1714 closed ports
    PORT   STATE SERVICE
    80/tcp open  http
    Device type: general purpose
    Running: Linux 2.6.X
    OS details: Linux 2.6.17 - 2.6.23
    Uptime: 2.854 days (since Fri Dec  5 15:49:01 2008)
    Network Distance: 0 hops
    TCP Sequence Prediction: Difficulty=205 (Good luck!)
    IP ID Sequence Generation: All zeros

    Read data files from: /usr/share/nmap
    OS detection performed. Please report any incorrect results at http://nmap.org/submit/ .
    Nmap done: 1 IP address (1 host up) scanned in 1.721 seconds
               Raw packets sent: 1734 (77.058KB) | Rcvd: 3472 (147.004KB)

NMAP is really that simple!

Sources: Router Mods I am the writer.