Installing vnstat Bandwidth Monitoring in CentOS 6 / RHEL 6

One of the most important aspects of system administration these days is monitoring the traffic on your server. Many hosting providers impose limits on how much you can transfer per month. If you go over these limits, it’s not really a problem from the data center’s point of view, but you will usually end up getting slapped with a fee per GB you transfer in excess of your limits. This can add up quickly if you have a busy site.