Currently the different browsers, servers and CA´s all implement different and incompatible ways to use SSL certificates for several VHosts on the same server.
The VHost SSL Taskforce tries to find an agreement between those ways, and publish that as an RFC afterwards, so that all the software vendors can agree on one way.
1. Way: SubjectAltName
- This is the official way, according to the RFC 2818. This was my discussion with Eric Rescorla (the author of the RFC) on the topic:
> Hi Eric, > > I would like to know your position regarding Multiple SSL/TLS Vhosts on the > same machine with the same IP Adress. (Name-based). > > In RFC 2818 you have written: > > Matching is performed using the matching rules specified by > [RFC2459]. If more than one identity of a given type is present in > the certificate (e.g., more than one dNSName name, a match in any one > of the set is considered acceptable.) Names may contain the wildcard > character * which is considered to match any single domain name > component or component fragment. E.g., *.a.com matches foo.a.com but > not bar.foo.a.com. f*.com matches foo.com but not bar.com. > > I would interpret it as if the solution for the problem is to have several > identities (dNSName lines) in one certificate for the different DNS Names, > and that the Browser has to accept any of them: > > dNSName: www.customer1.at > dNSName: www.customer2.com > dNSName: www.customer3.de > > Is that a correct interpretation? That's certainly one possibility, and it's the only one that will work with Name Based Virtual Hosts without the domain name extension (not yet widely deployed)
How can I generate a certificate for that?
How can I generate such a certificate?
2. Way: Multiple CommonName´s in the same certificate
How can I generate a certificate for that?
How can I generate such a certificate?
3. Way: Regular Expressions as CommonName: (www|mail).futureware.at
4. Way: Multiple certificates in the certificate chain/graph
5. Way: TLS "server name indication".
- There is a TLS extension called "server name indication". It is currently not implemented by NSS . There are RFEs, you can search bugzilla. I'm not aware of any client or server that implements this extension at this time, but if you are, that might provide an incentive to add it to NSS .
Interoperability Test
Vendor/App |
Way 1 |
Way 2 |
Way3 |
Way 4 |
Way 5 |
CAcert |
Yes |
Yes |
No |
Yes |
Yes |