User guide

Chapter 1. Security Overview

1.2.3.1.1. Using Nmap

Nmap can be run from a shell prompt by typing the nmap command followed by the hostname or IP

address of the machine to scan.

nmap foo.example.com

The results of a basic scan (which could take up to a few minutes, depending on where the host is

located and other network conditions) should look similar to the following:

Interesting ports on foo.example.com:

Not shown: 1710 filtered ports

PORT STATE SERVICE

22/tcp open ssh

53/tcp open domain

80/tcp open http

113/tcp closed auth

Nmap tests the most common network communication ports for listening or waiting services. This

knowledge can be helpful to an administrator who wants to close down unnecessary or unused

services.

For more information about using Nmap, refer to the official homepage at the following URL:

http://www.insecure.org/

1.2.3.2. Nessus

Nessus is a full-service security scanner. The plug-in architecture of Nessus allows users to customize

it for their systems and networks. As with any scanner, Nessus is only as good as the signature

database it relies upon. Fortunately, Nessus is frequently updated and features full reporting, host

scanning, and real-time vulnerability searches. Remember that there could be false positives and false

negatives, even in a tool as powerful and as frequently updated as Nessus.

Note

The Nessus client and server software requires a subscription to use. It has been included in this

document as a reference to users who may be interested in using this popular application.

For more information about Nessus, refer to the official website at the following URL:

http://www.nessus.org/

1.2.3.3. Nikto

Nikto is an excellent common gateway interface (CGI) script scanner. Nikto not only checks for CGI

vulnerabilities but does so in an evasive manner, so as to elude intrusion detection systems. It comes

with thorough documentation which should be carefully reviewed prior to running the program. If you

have Web servers serving up CGI scripts, Nikto can be an excellent resource for checking the security

of these servers.

More information about Nikto can be found at the following URL:

http://cirt.net/nikto2