[openssl-users] s_client/s_server trouble

Viktor Dukhovni openssl-users at dukhovni.org
Thu May 19 16:19:42 UTC 2016

On Thu, May 19, 2016 at 05:58:11PM +0200, Jakob Bohm wrote:

> What kind (and size) of keys are in your certificates?
> That sounds like the most likely issue.

Perhaps that dhparam2049.pem does not actually contain a 2048-bit
prime.  I don't recall a floor on RSA key sizes in 1.0.1.

The CHANGES file lists for 1.0.1q:

  *) Reject DH handshakes with parameters shorter than 1024 bits.
     [Kurt Roeckx]

Otherwise, I don't see any enforcement of key size floors in 1.0.1.

> > >- I've set up a PKI with a ca.crt file and a server.crt/server.key
> > >  keypair

Not posting the certs makes it rather difficult to offer any help.

> > >- next , I run
> >>
> >>  ~/src/openssl-1.0.1t/apps/openssl s_server -CAfile ca.crt -cert
> >>server.crt -key server.key  -dhparam dh2048.pem

I don't see a "-accept 4433" in that command.

> >>- then, with s_client
> >>
> >>  ~/src/openssl-1.0.1t/apps/openssl s_client -CAfile ca.crt -connect
> >>

What's listening on "4433"?

> >>and I always end up with
> >>
> >>  Verify return code: 21 (unable to verify the first certificate)
> >>
> >>If I either change s_server *or* s_client to use openssl 0.9.8 then the
> >>above commands work!

With 0.9.8 s_client or s_server will be able to use the default
CApath that is probably hashed with the 0.9.8-compatible hash
algorithm, allowing either or both to construct a more complete

Likely the "ca.crt" you're using is not the (immediate?) issuer
of the server certificate.


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