Richard Stiennon has published a blog post on Netasq, a European UTM vendor called, A brief history of firewalls and the rise of the UTM. I found the post indirectly from Alan Shimmel’s post about it.
Stiennen seems to think that Next Generation Firewalls are just a type of UTM. Shimmel also seems to go along with Stiennon’s view. Stiennon gives credit to IDC for defining the term UTM, but has not acknowledged Gartner’s work in defining Next Generation Firewall.
My purpose here is not to get into a debate about terms like UTM and NGFW. The real question is which network security device provides the best network security “prevention” control. The reality is that marketing people have so abused the terms UTM and NGFW, you cannot depend on the term to mean anything. My remarks here are based on Gartner’s definition of Next Generation Firewall which they published in October 2009.
All the UTMs I am aware of, whether software-based or with hardware assist, use port-based (stateful inspection) firewall technology. They may do a lot of other things like IPS, URL filtering and some DLP, but these UTMs have not really advanced the state (pardon the pun) of “firewall” technology. These UTMs do not enable a positive control model (default-deny) from the network layer up through the application layer. They depend on the negative control model of their IPS and application modules/blades.
Next Generation Firewalls, on the other hand, as defined by Gartner’s 2009 research report, enable positive network traffic control policies from the network layer up through the application layer. Therefore true NGFWs are something totally new and were developed in response to the changes in the way applications are now written. In the early days of TCP/IP, port-based firewalls worked well because each new application ran on its assigned port. For example, SMTP on port 25. In the 90s, you could be sure that traffic that ran on port 25 was SMTP and that SMTP would run only port 25.
About ten years ago applications began using port-hopping, encryption, tunneling, and a variety of other techniques to circumvent port-based firewalls. In fact, we have now reached the point where port-based firewalls are pretty much useless at controlling traffic between networks of different trust levels. UTM vendors responded by adding application identification functionality using their intrusion detection/prevention engines. This is surely better than nothing, but IPS engines use a negative enforcement model, i.e. default allow, and only monitor a limited number of ports. A true NGFW monitors all 65,535 ports for all applications at all times.
In closing, there is no doubt about the value of a network security “prevention” control performing multiple functions. The real question is, does the device you are evaluating fulfill its primary function of reducing the organization’s attack surface by (1) enabling positive control policies from the network layer through the application layer, and (2) doing it across all 65,535 ports all the time?