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Tag Archives: firewall

Distributed Firewall ALG

In the last post, VMware NSX™ Distributed Firewall installation and operation was verified. In this entry, the FTP (file transfer protocol) ALG (Application Level Gateway) is tested for associating data connections with originating control connections – something a stateless ACL (access control list) can’t do.

An added benefit over stateless ACLs – most compliance standards more easily recognize a stateful inspection-based firewall for access control requirements. Continue reading

Getting Started with VMware NSX Distributed Firewall – Part 2

In Part 1, I covered traditional segmentation options. Here, I introduce VMware NSX Distributed Firewall for micro-segmentation, showing step-by-step how it can be deployed in an existing vSphere environment.

Now, I have always wanted a distributed firewall. Never understood why I had to allow any more access to my servers than was absolutely necessary. Why have we accepted just network segmentation for so long? I want to narrow down allowed ports and protocols as close to the source/destination as I can.

Which brings me to my new favorite tool – VMware NSX Distributed Firewall. Continue reading

Getting Started with VMware NSX Distributed Firewall – Part 1

Who saw it coming that segmentation would be a popular term in 2015?!? Gartner analyst StartGreg Young was almost apologetic when he kicked off the Network Segmentation Best Practices session at the last Gartner Security Summit.

As a professional with a long history in the enterprise firewall space, I know I found it odd at first. Segmentation is such a basic concept, dovetailing with how we secure networks – historically on network boundaries. Network segmentation is the basis for how we write traditional firewall rules – somehow get the traffic TO the firewall, and policy can be executed. How much more can we say about network segmentation? Continue reading

What is a Distributed Firewall?

In the post “What is Network Virtualization?” I described a model where the application’s complete L2-L7 virtual network is decoupled from hardware and moved into a software abstraction layer for the express purpose of automation and business agility. In this post I’ll focus on network security, and describe an imminent firewall form factor enabled by Network Virtualization — the Distributed Firewall.


If InfoSec ruled the world … well, OK, maybe not the world … if InfoSec ruled the data center network design, and if money was no object, we would probably have something like this. Every server in the data center directly connected to its own port on one massive firewall. Every packet sent from every server would be inspected against a stateful security policy before going anywhere. And every packet received by every server would pass one final policy check before hitting the server’s NIC receive buffer. The firewall wouldn’t care about the IP address of the servers, for the simple reason that it’s directly connected to every server. E.g. “The server on this port can talk to the server on that port, on TCP port X”. And if that wasn’t good enough, the firewall knows everything about the servers connected to it, and can create rules around a rich set of semantics. All of this with no performance penalty. That would be awesome, right? Continue reading