Monday, June 8, 2009

[Exchange 2007] Renewing an SSL Certificate

While there are a number of great guides designed to teach a budding Exchange Administrator how to add a brand new SSL certificate to your Exchange system, there seems to be a severe lack of guides to renew said SSL cert. As most of us administrators will spend more time renewing these pesky annual certificates rather than doing the first install I figured I needed to save this little gem so I can easily refer back to it year after year...


Some items of note before we get started.

I've only tested this on my configuration, your systems may vary. This was tested on a fairly standard Exchange 2007 SP1 system running on Windows 2003 R2. Also this is not for the self-signed internal Exchange certificate (that process can be found here), this process is for your external facing SSL certificate (which I would assume is a purchased valid certificate from a 3rd Party root CA such as Verisign, Thwate, or even say GoDaddy if you are seeking a discount wildcard SSL cert).

So without further delay away we go.



Administrators familiar with say IIS based renewals will likely be tripped up by the very first step, to begin the renewal process in Exchange 2007 you actually don't do a "renewal" per-say instead you'll want to issue a new certificate request - there are two options here - both are launched from the Exchange Management Shell:

Option 1: Issue a SAN (Subject Alternative Names) Certificate - also called a wildcard certificate. These certs are very helpful for exchange environments as it can be used to replace the self-signed Exchange certificate as well as work for the multiple exchange sites such as autodiscover, owa.company.com, mail.company.com, etc.



New-Exchangecertificate -domainname mail.company.com, company.com, company.local, autodiscover.company.com, autodiscover.company.local, servername01.company.local, servername01 -Friendlyname companyExchCrt -generaterequest:$true -keysize 1024 -path c:\cerReq.csr -privatekeyexportable:$true -subjectname "c=US, s=Texas, l=Dallas, o=Company Name, ou=IT, cn=mail.company.com"




Option 2: Issue a Standard single domain certificate - useful for OWA only or environments that want to keep the self-signed exchange certificate - also MUCH cheaper.

New-ExchangeCertificate -GenerateRequest:$true -keysize 1024 -path c:\cerReq.csr -privatekeyexportable:$true -SubjectName "c=US, s=Texas, l=Dallas, o=Company Name, ou=IT, cn=mail.company.com"





Under SubjectName you'll want to fill your values in appropriately.

c= Your 2 digit Country
s= Your State (I tend to spell it out, though some just use the standard 2 character state code)
l= Your Locality (City, Region, it's up to you)

o= Your company name
ou= Your Organizational Unit (common here is IT/IS Department or just omit if not required)
cn= the common name of the certificate. This is important as it is the name the certificate will be issued on - if you are using this Certificate for OWA or even secure SMTP/POP access you will want this to match your MX DNS record (such as mail.company.com or owa.company.com - not as critical with a SAN cert).




Now the fun begins, you go to your certificate provider and go though the renewal process, when prompted attach or copy the text from your CSR file (c:\cerReq.csr if you followed the example above) and wait for your new certificate to be emailed back to you (or retrieved from the company's website).

Save this new certificate in a file called exchcert.cer on the root of your c:\

Note: if you get it from a web page you may need to copy everything from:
-----BEGIN CERTIFICATE-----
to
-----END CERTIFICATE-----
into a text file (using notepad) and save it as c:\exchcert.cer




Open the Exchange Management Shell

Issue the following command



Get-ExchangeCertificate | fl | out-file -filePath c:\CurrentCerts.txt




This will export all the certificates on the server to a text file, when opened it looks like this:


AccessRules : {System.Security.AccessControl.CryptoKeyAccessRule, System.Security.AccessControl.CryptoKeyAccessRule, System.Security.AccessControl.CryptoKeyAccessRule}
CertificateDomains : {mail.company.com}
HasPrivateKey : True
IsSelfSigned : False
Issuer : OU=www.verisign.com/CPS Incorp.by Ref. LIABILITY LTD.(c)97
VeriSign, OU=VeriSign International Server CA - Class 3,
OU="VeriSign, Inc.", O=VeriSign Trust Network
NotAfter : 4/18/2009 6:59:59 PM
NotBefore : 3/26/2008 7:00:00 PM
PublicKeySize : 1024
RootCAType : ThirdParty
SerialNumber : 29BBFFD5AAAB541AB9BB2A73139AG335
Services : IMAP, POP, IIS, SMTP
Status : Valid
Subject : CN=mail.company.com, OU=Terms of use at verisign.com/rpa (c)05, OU=IT, o=company name, L=Dallas, S=Texas, C=US
Thumbprint : C21DE04E3123210AD28E430742C21D0194F46421




Two things to note here,
Services: - these two are important to the next step - depending on what you use the current certificate for you will want to make sure the renewal cert does the same thing (in the example above this certificate does IMAP, POP, IIS, and SMTP)

Thumbprint: - this is used to delete the old certificate which is our next step.


Remove-ExchangeCertificate -thumbprint [old certificate thumbprint]





from the example above:

Remove-ExchangeCertificate -thumbprint C21DE04E3123210AD28E430742C21D0194F46421




You will get a confirmation to remove the old certificate, you'll want to type Y to remove it.

Now you are almost done, we just need to add the newly renewed certificate back into the system.



Import-ExchangeCertificate -path c:\exchcert.cer | Enable-
ExchangeCertificate -Services [your services from above]




Using our example you will want to do the following to get the certificate working on all services (except Unified Messaging - UM).


Import-ExchangeCertificate -path c:\exchcert.cer | Enable-
ExchangeCertificate -Services IMAP, POP, IIS, SMTP




Now just to confirm all is working as expected, you will want to issue the following command


Get-ExchangeCertificate




This will display something similar to this:


Thumbprint Services Subject
---------- -------- -------
C32DE24E1214210AD28E030742C21D0194F060D1 IP.WS CN=mail.company.com





This shows you the new cert (with it's new thumbprint) is active on I (IMAP), P (POP), . (not U for Unified Messaging), W (Web or IIS), S (SMTP)

That's it you are all done and renewed! Happy mailing!

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