Windows firewall is not allowing inbound communications

P Mowleeswaran 20 Reputation points
2024-10-22T05:34:00.69+00:00

Hello Team,

I have 3 machines with different network CIDR and i have enabled windows defender firewall for all machines from the GPO and rules also applied from GPO. i have created a Inbound rule for port 445 for workstation GPO (Local Address 10.4.100.10, Remote Address 10.4.30.3) and applied for workstation.

But when i do the Test-netconnection -computername 10.4.100.10 -port 445 is failing from source machine 10.4.30.3

But when configure the same Inbound rule for entire subnet (Local Address 10.4.100.0/28, Remote Address 10.4.30.0/27), Test-netconnection is passing from the source machine 10.4.30.3

Could you please help me to understand this issue and how i can fix this.

Note: machines are connected to the network without any problem (able to ping and join to the domain),Rules enabled for all profiles for all the machines and Inbound connections Block (Default) & Outbound Connections Allow (Default) configured as per Microsoft recommendation (PFA), there is no blocking rule for any port on both source and destination for inbound and outbound. There is no physical firewall in between the source and destination.

All the machines configured with static ip address.

Domain Controller (Windows 2022 Core):

Network: 10.4.20.0/27

Ip Address: 10.4.20.3

Subnet mask : 255.255.255.224

Gateway: 10.4.20.1

Windows Server(Windows 2022 GUI):

Network: 10.4.30.0/27

Ip Address: 10.4.30.3

Subnet mask : 255.255.255.224

Gateway: 10.4.30.1

Workstation (Windows 11):

Network: 10.4.100.0/28

Ip Address: 10.4.100.10

Subnet mask : 255.255.255.240

Gateway: 10.4.100.1

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  1. Daisy Zhou 24,981 Reputation points Microsoft Vendor
    2024-10-23T07:16:57.4266667+00:00

    Hello P Mowleeswaran,

    Thank you for posting in Q&A forum.

     It sounds like you have checked some possible reasons. There are also 2 steps you could try:

    1. Check the Event Viewer for any logs related to firewall rule application. This can provide insights into why a specific rule might not be working as expected.
    2. Use Network monitor to compare what’s the difference between 2 GPO applied.

    Reference:

    Collect data using Network Monitor - Windows Client | Microsoft Learn

    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

    ============================================

    If the Answer is helpful, please click "Accept Answer" and upvote it.

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