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
document
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
finished.
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.
Additional Resources:
About the Author
Don Jones has more than a decade of professional experience in the IT industry. He's the author of more than 30 IT books, including Windows PowerShell: TFM; VBScript, WMI, and ADSI Unleashed; Managing Windows with VBScript and WMI; and many more. He's a top-rated and in-demand speaker at conferences such as Microsoft TechEd and TechMentor, and writes the monthly Windows PowerShell column for Microsoft TechNet Magazine. Don is a multiple-year recipient of Microsoft's "Most Valuable Professional" (MVP) Award with a specialization in Windows PowerShell. Don's broad IT experience includes work in the financial, telecommunications, software, manufacturing, consulting, training, and retail industries and he's one of the rare IT professionals who can not only "cross the line" between administration and software development, but also between IT workers and IT management.