Click here to close now.


Blog Feed Post

How To Protect Your Network: Microsoft ISA Firewall Server Best Practices

Microsoft Internet Security and Acceleration (ISA) ServerThis is the third article in our series “Protecting Your Network”. We previously discussed common firewall best practices and compared some of the most popular products to manage your network security. In this article we’ll focus on best practices specifically to Microsoft Internet Security and Acceleration (ISA) Server.

Let’s start looking at some recommendations to configure then Microsoft ISA firewall so it provides the best level of security, reliability and performance possible. There are too many items to describe all of them in this article, so we’ll focus on the most important items that you should pay attention to. The overview is not in any particular order so items higher in the list are not necessarily more important.

  1. ISA Server comes with a Firewall and Web Proxy client. You should deploy these clients to get superior performance over what a hardware firewall provides. The combination of ISA server and its clients provide an intelligent security solution, more so than an appliance without clients can offer.
  1. The ISA firewall should have only one DNS server configured on its interfaces, and that DNS server address must be configured on its internal interface (or whatever interface is closest to an internal DNS server that can resolve Internet host names). Never put an external DNS server on any of the ISA firewall’s interfaces, and never enter a DNS server address on more than one ISA firewall interface.
  1. When investigating a possible attack, use and do a Whois search on the IP address. This should be the first thing you do when you detect unusual activity in your firewall logs.
  1. Use DMZ networks connected to the ISA firewall to limit access to different security zones within your organization. Put ISA firewalls between different security zones to make sure you are protected against attacks sourcing from different security zones.
  1. Do not consolidate other server functions (file server, web server, etc) with the ISA server. The ISA firewall is a just that; a firewall.
  1. Harden the server using the ISA firewall hardening guides located at
  1. Typically there is no reason to enable NetBT on the external interface of the ISA firewall. If you don’t need it, disable it.
  1. There typically isn’t a reason to enable the Server service on the external interface of the ISA firewall, as it is used to enable access to shared resources on the ISA firewall. In general, the Server service should be disabled on all interfaces of the ISA firewall, but there can be side effects, such as being unable to access the Firewall client share on the ISA firewall if you installed it there. It is best to place the client installation files on a network share hosted by a file server. You shouldn’t run into any issues if the Server service is unbound only from the external interface.
  1. On Windows 2000, the Alerter and Messenger services should be disabled on the ISA firewall. Windows Server 2003 turns off these services by default, or they are turned off as part of running the Security Configuration Wizard on a Windows Server 2003 Service Pack 1 ISA firewall.
  1. Install Network monitor for troubleshooting issues. Microsoft Network Monitor comes with Windows, and you can install it Monitor either before or after the ISA firewall software is installed.
  1. The ISA firewall shouldn’t be used as a workstation; it is a network firewall representing an important component of your network security infrastructure. Don’t use client applications, such as Internet Explorer, on the ISA firewall and don’t disable the enhanced IE security configuration that is part of Windows Server 2003 Internet Explorer.
  1. If users complain about decreased performance of the Web, configure the clients as Web Proxy clients and configure the web browsers to use HTTP 1.1.
  1. Make sure to patch the base operating system before installing ISA. Innstall the base operating system on a protected network, so that you can safely install the operating system and then update the operating system before installing the ISA firewall software. Connect the ISA firewall device to the Internet only after the operating system is patched and the ISA firewall software is installed.
  1. You can rename the network interfaces installed on the ISA firewall from Local Area Connection 1 and Local Area Connection 2 to something more meaningful, such as WAN, LAN, and DMZ. This is helpful when you have a lot of interfaces installed on the ISA firewall device.
  1. The ISA firewall can mitigate worm and other automated attacks by enforcing connection limits. You can configure connection limits by going to the General node in the ISA firewall console and Define Connection Limits.

The above list represents only some of the recommendation to configuring your ISA Firewall and certainly doesn’t cover all of the aspects. If you want to analyze your implementation of ISA Server it is a good idea to download the Microsoft Best Practice Analyzer Tool from the Microsoft website and run this against your ISA Server. The tool is compatible with ISA Server 2004, 2006, and Forefront TMG:

The Microsoft TechNet website is a great resource that offers a lot of information about how to configure your ISA server for your environment, performance best practices ( , and troubleshooting performance issues (

Recommended Metrics for Load and Security Monitoring

To maintain and manage the health of ISA Server, it is necessary to monitor its performance and watch for any possible anomalies. The following sections list resource counters and ISA Server counters that help troubleshoot ISA Server performance problems. It is recommended that these counters be samples on a regular basis at a rate of several samples per minute.

The performance counters that should be tracked can be grouped in the following categories:

Base subsystem metrics:

  • Processor Subsystem
  • Network Subsystem
  • Disk Subsystem

ISA Server specific metrics:

  • ISA Server Firewall Engine
  • ISA Server Firewall Service
  • ISA Server Web Proxy
  • ISA Server Cache

Between the Processor, Disk, and Network subsystems, as well as the ISA specific metrics, there are many counters that can be measured, but for the purpose of providing a general, yet effective monitor, we’ll focus on the most recommended performance counters only. For those interested, a complete overview of the subsystem metrics and all the ISA supported performance counters can be found in the article; Advanced ISA Monitoring.

Microsoft recommends that, to monitor the general performance of your ISA server, the following metrics should be monitored:

Load Monitoring

Performance Counter Description
ISA Server Firewall Engine Active Connections
ISA Server Firewall Service Active Sessions
ISA Server Web Proxy Requests/sec
ISA Server Firewall Engine Bytes/sec
Security Monitoring
Category Performance Counter Name
ISA Server Firewall Engine Dropped packets/sec
ISA Server Firewall Engine Packets/sec
ISA Server Firewall Engine Connections/sec
ISA Server Web Proxy Average Milliseconds/request

These metrics offer a generic insight in your ISA server’s performance. Like previously mentioned, ISA server offers a lot more performance counters that can be queried to get more detailed information about the Firewall Engine, Web Proxy, and ISA cache. These will be discussed in the article; Advanced ISA Monitoring. The basic performance metrics that we mentioned in this article are included in the Custom Monitis ISA Monitor that is available for download. You can find full details about this monitor in the article: “Monitoring ISA Server with Monitis”.

Share Now:del.icio.usDiggFacebookLinkedInBlinkListDZoneGoogle BookmarksRedditStumbleUponTwitterRSS

Read the original blog entry...

More Stories By Hovhannes Avoyan

Hovhannes Avoyan is the CEO of PicsArt, Inc.,

Latest Stories
In his General Session at DevOps Summit, Asaf Yigal, Co-Founder & VP of Product at, explored the value of Kibana 4 for log analysis and provided a hands-on tutorial on how to set up Kibana 4 and get the most out of Apache log files. He examined three use cases: IT operations, business intelligence, and security and compliance. Asaf Yigal is co-founder and VP of Product at log analytics software company In the past, he was co-founder of social-trading platform Currensee, which...
The Internet of Things (IoT) is growing rapidly by extending current technologies, products and networks. By 2020, Cisco estimates there will be 50 billion connected devices. Gartner has forecast revenues of over $300 billion, just to IoT suppliers. Now is the time to figure out how you’ll make money – not just create innovative products. With hundreds of new products and companies jumping into the IoT fray every month, there’s no shortage of innovation. Despite this, McKinsey/VisionMobile data...
Culture is the most important ingredient of DevOps. The challenge for most organizations is defining and communicating a vision of beneficial DevOps culture for their organizations, and then facilitating the changes needed to achieve that. Often this comes down to an ability to provide true leadership. As a CIO, are your direct reports IT managers or are they IT leaders? The hard truth is that many IT managers have risen through the ranks based on their technical skills, not their leadership ab...
Just over a week ago I received a long and loud sustained applause for a presentation I delivered at this year’s Cloud Expo in Santa Clara. I was extremely pleased with the turnout and had some very good conversations with many of the attendees. Over the next few days I had many more meaningful conversations and was not only happy with the results but also learned a few new things. Here is everything I learned in those three days distilled into three short points.
DevOps is about increasing efficiency, but nothing is more inefficient than building the same application twice. However, this is a routine occurrence with enterprise applications that need both a rich desktop web interface and strong mobile support. With recent technological advances from Isomorphic Software and others, rich desktop and tuned mobile experiences can now be created with a single codebase – without compromising functionality, performance or usability. In his session at DevOps Su...
As organizations realize the scope of the Internet of Things, gaining key insights from Big Data, through the use of advanced analytics, becomes crucial. However, IoT also creates the need for petabyte scale storage of data from millions of devices. A new type of Storage is required which seamlessly integrates robust data analytics with massive scale. These storage systems will act as “smart systems” provide in-place analytics that speed discovery and enable businesses to quickly derive meaningf...
In his keynote at @ThingsExpo, Chris Matthieu, Director of IoT Engineering at Citrix and co-founder and CTO of Octoblu, focused on building an IoT platform and company. He provided a behind-the-scenes look at Octoblu’s platform, business, and pivots along the way (including the Citrix acquisition of Octoblu).
In his General Session at 17th Cloud Expo, Bruce Swann, Senior Product Marketing Manager for Adobe Campaign, explored the key ingredients of cross-channel marketing in a digital world. Learn how the Adobe Marketing Cloud can help marketers embrace opportunities for personalized, relevant and real-time customer engagement across offline (direct mail, point of sale, call center) and digital (email, website, SMS, mobile apps, social networks, connected objects).
The buzz continues for cloud, data analytics and the Internet of Things (IoT) and their collective impact across all industries. But a new conversation is emerging - how do companies use industry disruption and technology enablers to lead in markets undergoing change, uncertainty and ambiguity? Organizations of all sizes need to evolve and transform, often under massive pressure, as industry lines blur and merge and traditional business models are assaulted and turned upside down. In this new da...
In recent years, at least 40% of companies using cloud applications have experienced data loss. One of the best prevention against cloud data loss is backing up your cloud data. In his General Session at 17th Cloud Expo, Sam McIntyre, Partner Enablement Specialist at eFolder, presented how organizations can use eFolder Cloudfinder to automate backups of cloud application data. He also demonstrated how easy it is to search and restore cloud application data using Cloudfinder.
The Internet of Everything is re-shaping technology trends–moving away from “request/response” architecture to an “always-on” Streaming Web where data is in constant motion and secure, reliable communication is an absolute necessity. As more and more THINGS go online, the challenges that developers will need to address will only increase exponentially. In his session at @ThingsExpo, Todd Greene, Founder & CEO of PubNub, exploreed the current state of IoT connectivity and review key trends and t...
Two weeks ago (November 3-5), I attended the Cloud Expo Silicon Valley as a speaker, where I presented on the security and privacy due diligence requirements for cloud solutions. Cloud security is a topical issue for every CIO, CISO, and technology buyer. Decision-makers are always looking for insights on how to mitigate the security risks of implementing and using cloud solutions. Based on the presentation topics covered at the conference, as well as the general discussions heard between sessi...
We all know that data growth is exploding and storage budgets are shrinking. Instead of showing you charts on about how much data there is, in his General Session at 17th Cloud Expo, Scott Cleland, Senior Director of Product Marketing at HGST, showed how to capture all of your data in one place. After you have your data under control, you can then analyze it in one place, saving time and resources.
With all the incredible momentum behind the Internet of Things (IoT) industry, it is easy to forget that not a single CEO wakes up and wonders if “my IoT is broken.” What they wonder is if they are making the right decisions to do all they can to increase revenue, decrease costs, and improve customer experience – effectively the same challenges they have always had in growing their business. The exciting thing about the IoT industry is now these decisions can be better, faster, and smarter. Now ...
The cloud. Like a comic book superhero, there seems to be no problem it can’t fix or cost it can’t slash. Yet making the transition is not always easy and production environments are still largely on premise. Taking some practical and sensible steps to reduce risk can also help provide a basis for a successful cloud transition. A plethora of surveys from the likes of IDG and Gartner show that more than 70 percent of enterprises have deployed at least one or more cloud application or workload. Y...