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Exchange Certs after Oct 2015

Okay, I seem to be running into this a bit lately, but nobody seems to be able to answer this. When setting up an Exchange server 2007/2010 I used to get a UCC certificate that has the following names in them:
exchange.company.local
autodiscover.company.com
mail.company.com

These three entries would get me up an running in a single server Exchange setup. But, now if I request a certificate that is past Oct 2015, I'm being told I can't have the exchange.company.local included.

So how do I get my internal users to connect with Outlook, if I don't have a certificate with the internal name on it?

Cliff Galiher

For smaller deployments, Exchange does not, never has, and most importantly (for security reasons) SHOULD not have certificates with .local in them. You set your URLs to a public FQDN via powershell and you deploy split DNS if necessary

for very large deployments, you can have internal CAS servers with private FQDN certificates issued by your internal CA but you'd want to prevent any and all public traffic to those CAS servers to prevent any MITM attacks.

so, in short, refer to the exchange deployment guides and pick your URLs accordingly so you can get a legit public cert.

Mahesh Sharma

Have you deployed this certificate on all exchange servers or on your public facing security device.

If exchange servers are using only self signed certs then you can go for internal CA certs
Other thing you may try is to create a CName record for .local pointing to some certificate name

Computech

ASKER

Well, what I have been doing may not be best practice, but it got the job done! Anyways, so I still don't see a solution here.

Exchange 2010 doesn't support having 2 certificates on a single service, so I can't have an internal cert and a public cert installed, to cover both internal users and external users.

I cannot change my internal domain on my AD to match, or to something real.

How does everyone do this? I can't be the only guy to run into this?

Cliff Galiher

As I said, you don't need to use your internal domain name at all. Simply set your various directories (you can do this in the GUI or PowerShell) to use a public FQDN. Those URLs will be what exchange gives to outlook clients (even internal ones) so those are the only names you need on the cert.

And if you want internal clients to hit an internal IP instead of looping out and back in through a router, you can additionally set up split DNS. Does that make more sense?

Computech

ASKER

I think so!? Let me repeat it back to make sure I'm understanding correctly.

So, I should go into my virtual directories and change the internal URLs to the same thing externally. Then, go and create a new zone in my DNS for my external domain so I can internally resolve my URLs.

Is this the recommended way to do this? I don't mind doing this, but I just want to make sure I'm not going to run into anymore issues with these certificates, by doing this.

Cliff Galiher

Yep

Computech

ASKER

Okay, so I tried what you suggested and I'm still getting a certificate error saying, because its still looking at the internal name. Anything else that I need to change? We've opened and closed Outlook a few times to see if it was something that needed to be propagated, but no joy.

Cliff Galiher

Make sure you'd updated all URLs, including OA, offline address books, EWS, and auto discover. Outlook's connectivity tests are also helpful in troubleshooting

ASKER CERTIFIED SOLUTION

Simon Butler (Sembee)

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Computech

ASKER

Once I followed the prescribed steps, the error in Outlook went away.