In todays world, all organization needs a secure network , to form secure network , they tend to intrude all the secure products into their network , so that it is non-vulnerable and secured in all aspects. Cisco products are world widely used to deploy such solution. Apart from cisco we have products from other vendors like, Symentac, Norton ,fortinet etc. Also there are some freeware solution available on Linux, which can be customized to suit your requirements.