SSH certificates - restricting to host groups

[Michael Ströder]

On 1/31/20 3:52 PM, Brian Candler wrote:
> On 31/01/2020 14:29, Michael Ströder wrote:
>> Hmm, personally I'd recommend not to issue user certs for generic user
>> names (e.g. "www"). While some cert information is logged by sshd it
>> requires keeping track of all issued certs in searchable data store to
>> be able to properly map logins to personal user accounts during an audit.
> 
> I thought that was the point of the certificate "identity" (-I) in
> addition to the "principals" (-n).  The login shows the certificate
> identity:
> 
> Jan 30 11:50:49 test1 sshd[4757]: Accepted publickey for alice from
> 2001_db8::2009 port 56943 ssh2: RSA-CERT ID brian (serial 1) CA RSA
> SHA256:fofx2XMj+RqnLlui09aDIuV9fWqPiU54oWStDzYr/p0
> 
> In this case, the cert identity was "brian"; cert principals were
> "alice" and "www"; ssh login was as user "alice".

Ah, ok. Description of semantics in ssh-keygen(1) is not really clear so
currently I've just set a UUID for each new key pair. But I could prefix
this with a user name.

> It's still a good idea to keep track of all issued certs though, in case
> you need to revoke one.

Or better get rid of the revocation requirement. ;-)

Ciao, Michael.