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Certificates required - WAF for MS Exchange

Hi folks

Sorry if this sounds trivial, but this is the first time I've used the Web Application Firewall for a production system using proper certificates, and I want to make sure I'm not about to make an expensive mistake!

I've followed the Sophos document on how to configure the UTM 9.2 WAF for Exchange connectivity, and I've got it to work using private certificates. I now want to replace my home-brew certificates with one(s) from one of the major certificate authorities. My question is - what do I need?

I've got three virtual servers configured:
  autodiscover..com
  outlook..com
  webservices..com

1. Do I just need certificates to cover the above external names, or do I need to worry about the internal DNS names for the exchange server as well?

2. Three separate certificates (which is what I used while testing) or one SAN certificate? Does it matter?

3. If a SAN certificate, does it matter which name goes in the subject field? (as you can guess, I'm not too knowledgeable about SAN certificates...)

Any other problems or "gotcha"s that I should be aware of when buying certificates for use with Sophos UTM?

Thanks for any guidance anyone can give...
Ifor

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0 Ifor Davies over 10 years ago

Thanks mod2402 and vilic - I think I've got it now:

To get the reverse proxy/Exchange stuff working properly, I just need certificates (SAN or otherwise) that cover the external host names

However, if I use a SAN certificate that also includes the internal host names:
- On the plus side, the internal clients won't show certificate errors
- On the minus side, the internal host names will be on the Internet for all and sundry to see

Is this a fair summary?
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0 mod2402 over 10 years ago in reply to Ifor Davies

Thanks mod2402 and vilic - I think I've got it now:

To get the reverse proxy/Exchange stuff working properly, I just need certificates (SAN or otherwise) that cover the external host names

However, if I use a SAN certificate that also includes the internal host names:
- On the plus side, the internal clients won't show certificate errors
- On the minus side, the internal host names will be on the Internet for all and sundry to see

Is this a fair summary?

You don't need internal hostnames. Please read the kb article:

Outlook 2007 security warning: "The name of the security certificate is invalid or does not match the name of the site"

But, as I mentioned before...
Every Consultant has his own prefered solution.

My prefered solution is "never use internal names in external accessible certificates" [;)]
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0 mod2402 over 10 years ago in reply to Ifor Davies

Thanks mod2402 and vilic - I think I've got it now:

To get the reverse proxy/Exchange stuff working properly, I just need certificates (SAN or otherwise) that cover the external host names

However, if I use a SAN certificate that also includes the internal host names:
- On the plus side, the internal clients won't show certificate errors
- On the minus side, the internal host names will be on the Internet for all and sundry to see

Is this a fair summary?

You don't need internal hostnames. Please read the kb article:

Outlook 2007 security warning: "The name of the security certificate is invalid or does not match the name of the site"

But, as I mentioned before...
Every Consultant has his own prefered solution.

My prefered solution is "never use internal names in external accessible certificates" [;)]
Cancel
Vote Up 0 Vote Down

Cancel

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