TFTP Client ! Issues with firewall (WIN11)

Question

Hello all,

my problem may sounds trivial, but it was driving me crazy.

I have issues with TFTP communication within my PC (WIN11) & my virtual Win Server 2022.

Important:

• Firewalls are configured on both systems (in/out rules with allowing comm. for UDP & port 69).
• On server is also added allowance for the tftpd64.exe in the: " Control Panel\System and Security\Windows Defender Firewall\Allow an app or feature... ".
• Test results = if the firewall on the SERVER is ON & firewall on my PC OFF, its working.

So the question is: what kind of additional rules I have to add (on my PC I assume) to make it work?

Thanks a lot in advance!

Marek

Answer 1

Hello,

Thank you for posting in Q&A forum.
Please try the suggestions below:

1.Check for Conflicting Rules:

Open Windows Defender Firewall with Advanced Security.

Go to Inbound Rules and Outbound Rules. Look for any rules that might be blocking TFTP traffic and disable them temporarily to see if it resolves the issue.

2.Verify TFTP Client Installation:

Ensure the TFTP client is correctly installed. Open Command Prompt and type tftp to see if the command is recognized. If not, reinstall the TFTP client via Control Panel > Programs > Turn Windows features on or off.

3.Temporarily Disable Antivirus:

Sometimes, third-party antivirus software can interfere with TFTP traffic. Temporarily disable your antivirus software and test the TFTP connection.

4.Use a Different TFTP Client:

Try using a different TFTP client like Tftpd64 to see if the issue persists. This can help determine if the problem is with the client software.

I hope the information above is helpful.

If you have any questions or concerns, please feel free to let us know.

Best Regards,

Daisy Zhou

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Answer 2

Hello Daisy Zhou, thank you for your answer!

Unfortunately:

1. I do not have any blocking rules in the inbound and outbound sections.
2. The TFTP Client is installed as you described.
3. I have tried the test with turning off the Microsoft antivirus, but it didn’t help. Only turning off the whole firewall allows the communication, which means the issue is probably within the firewall.
4. I want to use PowerShell.

Luckily:

By coincidence, I have found the solution for this issue while writing this comment.

Solution:
1.
Missing allowance for the application "TFTP.EXE" in this section: Control Panel\System and Security\Windows Defender Firewall\Allowed apps

TFTP.EXE path: "C:\Windows\System32\TFTP.EXE"

Added through "Allow another app..."

2.

Allowance for the "C:\Windows\System32\TFTP.EXE" in the antivirus section.

This issue was not only about firewall rules and UDP 69, because this port (69) is used only for initialization of communication. Afterwards, another port is dynamically chosen from a wide range, which is not possible to securely allow through inbound/outbound rules. Allowing the app through is the answer then. I am new to these topics and issues with Windows, which is why I did not know that TFTP.EXE exists and corresponds with the MS native TFTP client feature.

Have a nice day.
Marek

Answer 3