Avoid Using Non-Secure Software
Most network configuration, usernames, passwords, unsecure protocol like FTP, telnet and rsh commands,
data can be captured by anyone on the same network using a packet sniffer.
To avoid this, you need to remove these unsecure software by running this command:
sudo apt-get purge xinetd nis yp-tools tftpd atftpd tftpd-hpa telnetd rsh-server rsh-redone-server