nasty pasty nasty pasty - 1 year ago 111
Linux Question

Using openssl to get the certificate from a server

I am trying to get the certificate of a remote server, which I can then use to add to my keystore and use within my java application.

A senior dev (who is on holidays :( ) informed me I can run this:

openssl s_client -connect

To get a raw certificate dumped out, which I can then copy and export. I receive the following output:

depth=1 /C=NZ/ST=Test State or Province/O=Organization Name/OU=Organizational Unit Name/CN=Test CA
verify error:num=19:self signed certificate in certificate chain
verify return:0
23177:error:14094410:SSL routines:SSL3_READ_BYTES:sslv3 alert handshake failure:s3_pkt.c:1086:SSL alert number 40
23177:error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure:s23_lib.c:188:

I have also tried with this option


and this one (running on debian mind you)

-CApath /etc/ssl/certs/

But get the same error.

This source says I can use that CApath flag but it doesn't seem to help. I tried multiple paths to no avail.

Please let me know where I'm going wrong.

Answer Source

It turns out there is more complexity here: I needed to provide many more details to get this rolling. I think its something to do with the fact that its a connection that needs client authentication, and the hankshake needed more info to continue to the stage where the certificates were dumped.

Here is my working command:

openssl s_client -connect host:port -key our_private_key.pem -showcerts \
                 -cert our_server-signed_cert.pem

Hopefully this is a nudge in the right direction for anyone who could do with some more info.

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