[Freeipa-users] how to overcome same serial number in cert issue on different master servers?

[Fraser Tweedale]

On Tue, Nov 11, 2014 at 04:17:37AM +0000, Les Stott wrote:
> > -----Original Message-----
> > From: Fraser Tweedale [mailto:ftweedal at redhat.com]
> > Sent: Tuesday, 11 November 2014 1:59 PM
> > To: Les Stott
> > Cc: freeipa-users at redhat.com
> > Subject: Re: [Freeipa-users] how to overcome same serial number in cert
> > issue on different master servers?
> > 
> > On Tue, Nov 11, 2014 at 02:11:55AM +0000, Les Stott wrote:
> > > > -----Original Message-----
> > > > From: Fraser Tweedale [mailto:ftweedal at redhat.com]
> > > > Sent: Tuesday, 11 November 2014 12:51 PM
> > > > To: Les Stott
> > > > Cc: freeipa-users at redhat.com
> > > > Subject: Re: [Freeipa-users] how to overcome same serial number in
> > > > cert issue on different master servers?
> > > >
> > > > On Tue, Nov 11, 2014 at 01:40:50AM +0000, Les Stott wrote:
> > > > > Hi,
> > > > >
> > > > > I have a standard rhel6 deployment for FreeIPA in two environments.
> > > > >
> > > > > One environment is in our Production Data Center, The Other in our
> > > > > DR
> > > > Data Center.
> > > > >
> > > > > Both environments are setup with the same domain (mydomain.com)
> > > > > for
> > > > FreeIPA. This is to support dr/failover etc.
> > > > >
> > > > > In each environment, there is a master. In Prod its
> > > > > serverA.mydomain.com,
> > > > In DR its serverB.mydomain.com.
> > > > >
> > > > > The master in each environment gets a generated certificate by
> > > > > IPA. This
> > > > certificate shows a Serial Number of "0A"
> > > > >
> > > > > My problem is that because the certificates have the same
> > > > > Organization,
> > > > OU and Serial Number, I can only browse to one of them (using Firefox).
> > > > >
> > > > > If I browse to https://serverA.mydomain.com/ipa/ui/ and accept the
> > > > certificate it works fine.
> > > > > If I then try to browse to https://serverB.mydomain.com/ipa/ui/ it
> > > > > comes
> > > > up with the following error:
> > > > >
> > > > > "Your certificate contains the same serial number as another
> > > > > certificate
> > > > issued by the certificate authority. Please get a new certificate
> > > > containing a unique serial number. (Error code:
> > sec_error_reused_issuer_and_serial)"
> > > > >
> > > > > If I remove the stored browser certificate for serverA, then
> > > > > browse to
> > > > serverB, and accept the certificate, it works, but then the "same
> > > > serial number" error pops up for browsing serverA.
> > > > >
> > > > > Note: both environments were built separately and are not linked
> > > > > in
> > > > anyway (no replication between prod/dr).
> > > > >
> > > > > Is there a way to generate unique serial numbers for the masters?
> > > > >
> > > > > Thanks in advance,
> > > > >
> > > > > Les
> > > > >
> > > > >
> > > > >
> > > > Hi Les,
> > > >
> > > > Ideally, you should prevent this situation by using different common
> > > > names
> > > > (CN) for your CAs and server certifications across the different
> > > > environments.  If this is not possible, you can configure the Dogtag
> > > > CA to use random serial numbers:
> > > >
> > > >
> > http://dogtagpki.org/wiki/Random_Certificate_Serial_Numbers#How_to_U
> > > > se_Random_Certificate_Serial_Numbers
> > > >
> > > > This does not guarantee that you will not get serial number
> > > > collisions, but reduces the likelihood.
> > > >
> > >
> > > Thanks for the quick reply.
> > >
> > > In this case the common name is different between both environments.
> > > In prod the master was serverA, in DR the master was serverB. It just
> > > happened that way. So having a different CommonName doesn't help.
> > >
> > Do the CA certificates bear the same commonName?  This is probably what
> > Firefox uses to determine if there are serial number collisions.
> > 
> 
> It appears so.
> 
> The certificate for the CA on the master serverA shows:
> 
> Issued To
> Common Name (CN) serverA.mydomain.com
> Organization (O) mydomain.com
> Organizational Unit (OU) <Not part of certificate>
> Serial Number 0A
> Issued By:
> Common Name (CN) Certificate Authority
> Organization (O) mydomain.com
> Organizational Unit (OU) <Not part of certificate>
> 
> The certificate for the CA on the master serverB shows:
> 
> Issued To
> Common Name (CN) serverB.mydomain.com
> Organization (O) mydomain.com
> Organizational Unit (OU) <Not part of certificate>
> Serial Number 0A
> Issued By:
> Common Name (CN) Certificate Authority
> Organization (O) mydomain.com
> Organizational Unit (OU) <Not part of certificate>
> 
> 
> Shouldn't the Common Name of the CA be different? Or is it the same in order to make CA replication easier?
> 
Both environments were probably set up with the same CN for the CA
(perhaps a default name).  I don't think this has anything to do
with replication.

> Is there a way to re-issue certificates for the masters so they get unique serial numbers (without making the systems blow up)?
> 
You can manually renew a certificate using Certmonger:

    http://www.freeipa.org/page/Certmonger#Manually_renew_a_certificate

You should enable random serial numbers before doing this.

> Thanks,
> 
> Les
> 
> 
> 
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