How to enable arpon ( prevent arp spoofing)

To prevent arp poisoning in ubuntu.
you will have to install arpon
to install arpon run :

sudo apt-get install arpon

than you have to enable arpon by default by editing /etc/default/arpon
make it look like :

# Defaults for arpon initscript
# sourced by /etc/init.d/arpon
# installed at /etc/default/arpon by the maintainer scripts

# You must choose between static ARP inspection (SARPI) and
# dynamic ARP inspection (DARPI)
# For SARPI uncomment the following line (please edit also /etc/arpon.sarpi)
# DAEMON_OPTS="-q -f /var/log/arpon/arpon.log -g -s"

# For DARPI uncomment the following line
DAEMON_OPTS="-q -f /var/log/arpon/arpon.log -g -D"

# Modify to RUN="yes" when you are ready

than run :

sudo service arpon restart

(be careful in the default Ubuntu install the D is not capital and prevents arpon from starting)
and your done !