The best hacking tool on Ubuntu

1 Nmap
Nmap is one of the best network security scanners out there. Nmap will scan for all the computers and services that are currently running on the network.

Nmap is included within Ubuntu's repositories. So to install, use the following command:

    sudo apt-get install nmap

2 NetCat
NetCat is a fantastic little program written by a guy called 'Hobbit' in 1991. This tool is used for reading and writing to network locations using connections on either UDP or TCP.
Again, NetCat is also in the repositories, so to install, run the following command:

    sudo apt-get install netcat

3 Aircrack-ng
Aircrack-ng is the best tool out there for cracking and recovering 802.11 WEP & WPA-PSK keys. Once you have collected enough data packets, you are then able to recover the key from the data packets. This is defiantly a must have application to test your home wireless security.

To install:

    sudo apt-get install aircrack-ng

4 nessus
The Nessus® vulnerability scanner, is the world-leader in active scanners, featuring high speed discovery, configuration auditing, asset profiling, sensitive data discovery and vulnerability analysis of your security posture. Nessus scanners can be distributed throughout an entire enterprise, inside DMZs, and across physically separate networks.
To install:

sudo apt-get install nessus
sudo apt-get install nessusd

add a new user

sudo nessus-adduser