Solved Port 445 Newly Blocked By Update Needed For Local Sharing

May 23, 2017 at 21:04:48
Specs: Windows 10 and 8.1, varies
It seems Win 10 update added a "Block 445" Rule to the Win Firewall, but I need it to share files locally with other computers on my home network. Question is: Is it OK to disable rule (I have a good router)? Also this rule may have been there already, not sure but disabling it fixes the sharing problem.

This rule is not present in the Windows 8.1 Firewall on 2 other computers, just on Windows 10 machines. I disable the rule and sharing works fine again.

My systems are mixed: Window 8.1 and Windows 10, all are up to date. All have more than 6gb of RAM. 5 PC's in Network.

Today is May 23, 2017 and the file sharing problem just occurred yesterday and there was a Win 10 update yesterday: 2017-05 Update for Windows 10 Version 1607 for x64-based Systems (KB3150513)

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May 24, 2017 at 03:32:19
On each PC in your network, make sure "File & Printer Sharing" is added as an exception in the Windows Firewall settings.

Your internal networking should then function okay.

message edited by phil22

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May 24, 2017 at 21:59:07
The first thing I did was to check that. All are turned on.I even turned them off, saved and back on. I had full access to all shared drives until the update, and it just seems to be disabling files sharing on the Win 10 machines, not the 8.1's. Mainly I'm wondering if having port 445 open is putting me at risk on those machines, as I'm guessing this change was implemented because of the new world virus threat we are experiencing... but that's just a guess.

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May 25, 2017 at 07:13:15
✔ Best Answer
If you're opening port 445 (or any port for that matter) only within your LAN, you're not risking much. Opening ports to external traffic (by that I mean, opening them on the router/firewall separating your LAN from the internet) can, and does expose you. So to answer your question, "Mainly I'm wondering if having port 445 open is putting me at risk on those machines" If you're only opening this port locally on the LAN, then you're not risking much.

Since your shares all seem good, you could try disabling the windows built in firewall altogether and then see if you can share with the disabled machine. If you can, then you know for sure it's the built in firewall. Then you would have to troubleshoot the issue on one PC until you figure out what's causing it. From the sounds of it, opening 445 on your firewall hasn't fixed the issue. If that's the case, then you need to keep looking for the root cause.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***

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May 27, 2017 at 06:58:40
Thank you both for the replies. I'll keep looking into it.

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