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Using Windows Firewall On SBS2011 To Only Accept Port 25 Access For Certain IPs

Posted on 2014-11-19
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Last Modified: 2014-11-20
Hello, I run SBS 2011 which uses Server 2008 R2 and Exchange 2010.

I am using Exchange Online Protection to protect spam from getting to our network.

As is expected spam is getting through still since spammers can send directly to our server using port 25.

So I am trying to figure out how to deny access to this port for all addresses except the following ones:

http://technet.microsoft.com/library/dn163583(v=exchg.150).aspx

I can not find the SMTP port under "Windows Firewall with Advanced Security" so I'm not sure how Exchange configured the firewall there.

However, I did try to change the IP ranges in the network tab under the receive connector in the hub transport role of the server configuration. This broke everything, I could no longer get email, I got the following error:

#5.7.1 smtp;530 5.7.1 Client was not authenticated> #SMTP#

I am attaching the file "network_cap_1.JPG" to show what I have before I change anything. "network_cap_2.JPG" shows the EOP IP ranges added and when I add those I get the above error.

I checked the IP that EOP is using to deliver mail to me and that IP currently is  207.46.163.210, so that should be covered by the 207.46.163.0/24 scope, shouldn't it?

Also since I am leaving the default 10.1.1.0-10.1.1.0 & 10.1.1.2-10.1.1.255 entries alone I'm not understanding two things:

1) Why does adding the EOP IPs break everything
2) Why is any email coming in since those IP ranges are local and not external.

Help would be greatly appreciated.

Thanks.
network-cap-1.JPG
network-cap-2.JPG
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Question by:Pawel_Kowalski
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by:Asif Bacchus
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I have not used EOP before, but it sounds like you may not have the correct settings on the receive connector's Authentication and Permission Groups tabs.  What do you have selected on those tabs? IIRC, the firewall is setup by default to allow Exchange full access and the address/ports/IPs, etc. that is uses are controlled via Exchange itself using either the EMC or the EMS depending on your preferences.
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Did you make these changes on the Default <Server Name> receive connector or the Windows SBS Internet Receive <Server Name> receive connector?

You should be making these changes on the Windows SBS Internet Receive <Server Name> connector as this connector is configured by default for external emails.
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by:Gareth Gudger
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Personally I never make these lock downs on my Exchange Server but rather on my perimeter firewall. If you do want to make these on Exchange versus a perimeter firewall I would follow VB ITS instructions.
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by:Asif Bacchus
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@Gareth, I totally agree.  I usually do this on my firewall also.  
@OP, I was not sure if you were using a separate firewall and was under the impression you were just using the Windows firewall.  Could you post-back with that information?  Thanks.
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by:Pawel_Kowalski
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Thanks! That was the exact problem.

In regards to a perimeter firewall this location doesn't have one, very small office and essentially the SOHO router serves as the firewall (only ports 25 and 443 are forwarded). Doesn't have anything fancy like allowable IP for certain ports. Probably not the most secure method but the budget isn't there to do anything about it.

Thanks again.
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