Windows Tip Sheet
When the Firewall Burns
Troubleshoot your Windows Firewall with these key tips.
The Windows Firewall included in WinXP SP2 usually works fine...but when
it doesn't, troubleshooting can be a real pain. Microsoft offers a troubleshooting
in its Knowledge Base; here are some key tips from that doc
and my own experience:
- When possible, create firewall exceptions for applications, not ports. That
way the firewall can just allow applications to use whatever ports they need,
and you don't have to guess what those are.
- Use netstat –ano to identify ports in
use by running applications.
- Run tasklist > tasklist.txt and tasklist
/svc > services.txt to get a process and service inventory.
- Run firewall.cpl and, on the Advanced tab, modify
the security logging settings to create a firewall log. This is a great way
to see what the firewall is up to, but be sure to turn logging off when you're
By looking at the log and seeing what the firewall is doing, and by figuring
out exactly what exceptions need to be made for something to work, you'll
be able to configure the firewall accurately in less time, and with less trial-and-error.
Don Jones is a multiple-year recipient of Microsoft’s MVP Award, and is an Author/Evangelist for video training company Pluralsight. Don is also a co-founder and President of PowerShell.org, a community dedicated to Microsoft’s Windows PowerShell technology. Don has more than two decades of experience in the IT industry, and specializes in the Microsoft business technology platform. He’s the author of more than 50 technology books, an accomplished IT journalist, and a sought-after speaker and instructor at conferences worldwide. Reach Don on Twitter at @concentratedDon, or on Facebook at Facebook.com/ConcentratedDon.