Quick Network Hack

Step 1: Download, install and run Cain & Abel at http://www.oxid.it/cain.html.
Step 2: Click "Configure" in the top bar.
Step 3: In the "Sniffer" tab, click the adapter which is connected to
the network to be sniffed, then click "Apply", then "OK".
Step 4: Click the "Sniffer" tab in the main window.
Step 5: Click the network card in the top bar (2nd icon from the left).
Step 6: Click the "+" button in the top bar.
Step 7: Select "All hosts in my subnet", click "OK". Entries should
appear in the main window under the "IP address", "MAC address" and
"OUI fingerprint" headings.
Step 8: From the "Sniffer" tab, click "APR" in the bottom tab.
Step 9: Click the top right pane in the main window. Click the "+"
button in the top bar.
Step 10: Click on the router in the left pane. The router is generally
the entry which has the lowest final IP value (xxx.xxx.xxx.*).
Highlight the IP addresses to sniff in the right pane. Click "OK".
Step 11: Click the ARP icon in the top bar (3rd icon from the left).
Wait until other users have logged into websites on other computers.
Depending on the size of the network and the traffic which this
network receives, this can range from minutes to hours.
Step 12: After some time has passed, click "Passwords" in the bottom tab.
Step 13: In the left pane, select the bolded entries. The right pane
should show the time, server, username, password (in plaintext) and
site accessed.

Please use this tutorial with caution as most private institutions, as
well as countries, have strict rules and laws against network sniffing
and could lead to expulsion from an institution, as well as critical
litigation! This tutorial is for educational purposes only and should
only be used to demonstrate the security weaknesses of common
networking infrastructures.