Block port on hyper-v host

Question

Hi,

I need a help on how to block port 25 for all hyper-v guests.

VMNetworkAdapterExtendedAcl is no use for me as all needs to be done manually.

Thank you

Answer 1

Hi,

As in the above screenshot, you can block the ports by setting new rules to it:
First you specify the certain type you want to set:

Then the detailed settings:

Then the action you want to take:

Then the applying range:

Hope this will help.
Best regards,
Danny

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Answer 2

Hi Danny,

The firewall rule is not working for hyper-v guests.

Answer 3

Hi,
I’ve done some research, but most recommendations that concerns port 25 is to configure firewall rules while the rest is not to block it. Here’s an issue similar to yours, please take a look:
https://community.spiceworks.com/topic/2319994-block-port-25-on-hyper-v-hosts?utm_campaign=item&utm_medium=rss&utm_source=channel
Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.

Would you check this and see if there’s any incorrect configuration?

Thanks for your understanding.
Best regards,
Danny

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Answer 4

The basic rule for this question is that, your firewall in host would only be involved if your VM guests are using NAT-mode for networking. If your guest is using virtual NIC then you can't block in on host as all traffics would be bypassing the firewall.

However this could be managed with port ACLs of Hyper-V management cmdlet.