Useful tasks done with SSL and OpenSSL.

Qualys SSL Labs'

• SSL Server Test.
• SSL/TLS Capabilities of Your Browser.

Incomplete trust chains might trigger issues in some clients (e.g., mobiles). This happens for example, with Gandi's standard SSL certificates. But http://wiki.gandi.net/en/hosting/using-linux/tutorials/ubuntu/sslthis is easily solved.

Gandi's intermediate CA certificate is needed:

$ wget https://www.gandi.net/static/CAs/GandiStandardSSLCA.pem

And Apache needs to be told to provide it

httpd.conf

  <VirtualHost *:443>
 
        ServerName www.example.net
        [...]
        SSLEngine on
        [...]
        SSLCertificateChainFile /PATH/TO/GandiStandardSSLCA.pem
        SSLVerifyClient None
  </VirtualHost>

Alternatively, the intermediate certificate can be concatenated with the server certificate, which is then served normally:

$ cat $SERVER.crt GandiStandardSSLCA.pem

httpd.conf

# Stop using SSLv2 and SSLv3 (POODLE)
SSLProtocol -SSLv2 -SSLv3
 
# Disable weak Cpihers
SSLCipherSuite ALL:!aNULL:!ADH:!eNULL:!LOW:!EXP:RC4+RSA:+HIGH:+MEDIUM

httpd.conf

SSLInsecureRenegotiation off

$ export SERVER=`hostname -f`
$ openssl genrsa -out /etc/ssl/private/$SERVER.key 4096

From (there).

In /etc/ssl/openssl-$SERVER.cnf (or the system's, but it's not as tidy):

[req]
...
req_extensions = v3_req

...

[ v3_req ]
# Extensions to add to a certificate request
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment

# Some CAs do not yet support subjectAltName in CSRs.
# Instead the additional names are form entries on web
# pages where one requests the certificate...
subjectAltName          = @alt_names

[alt_names]
DNS.1 = IPADDRESS
DNS.2 = SECONDNAME
DNS.3 = THIRDNAME
...

The certificate request is then generated as usual, but the custom configuration file is specified.

$ openssl req -config /etc/ssl/openssl-$SERVER.cnf -new -key /etc/ssl/private/$SERVER.key -out /etc/ssl/$SERVER.csr

$ openssl x509 -config /etc/ssl/openssl-$SERVER.cnf -req -days 1000 -in /etc/ssl/$SERVER.csr -signkey /etc/ssl/private/$SERVER.key -out /etc/ssl/$SERVER.crt

$ openssl x509 -inform der -in /etc/ssl/$SERVER.crt -out /etc/ssl/$SERVER.pem

Reference: How to generate self-signed SSL certificates

$ openssl rsa -in /etc/ssl/private/$SERVER.key -out /etc/ssl/private/$SERVER-newpass.key -passout "pass:PASS"

$ openssl req|x509|rsa -in /etc/ssl/$SERVER.crt -text

$ openssl s_client -connect www.narf.ssji.net:443
CONNECTED(00000003)
---
Certificate chain
 0 s:/CN=distant-sun.narf.ssji.net
   i:/O=CAcert Inc./OU=http://www.CAcert.org/CN=CAcert Class 3 Root
---
Server certificate
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----
subject=/CN=distant-sun.narf.ssji.net
issuer=/O=CAcert Inc./OU=http://www.CAcert.org/CN=CAcert Class 3 Root
---
No client certificate CA names sent
---
SSL handshake has read 2983 bytes and written 409 bytes
---
New, TLSv1/SSLv3, Cipher is DHE-RSA-AES256-SHA
Server public key is 2048 bit
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1
    Cipher    : DHE-RSA-AES256-SHA
    Session-ID: C68B84A9F17B7F2FB2B5E043272B41BC37C34AA826D6B6458C321DE103BD95FC
    Session-ID-ctx:
    Master-Key: E9BFE1B8E6E7B26895541B5E87CC76D7E9E5FD620DE9BB5BDA2B2CFC446F17323CE79717466F8EEC828C1FC2C9E8C770
    Key-Arg   : None
    PSK identity: None
    PSK identity hint: None
    TLS session ticket:
    0000 - 37 a3 3f ae ad 81 6d 0d-97 36 10 44 6f 58 ec 49   7.?...m..6.DoX.I
    0010 - d0 74 e0 c6 d5 e6 76 a5-44 a7 1b b6 55 51 f5 65   .t....v.D...UQ.e
    0020 - 75 b0 f1 57 29 01 80 24-a1 bd 67 bf b6 9c b8 50   u..W)..$..g....P
    0030 - 67 f4 87 31 25 d2 0e ac-53 ab 1f 39 97 65 3d 38   g..1%...S..9.e=8
    0040 - a8 87 85 5b f3 7e ec a9-9d bc 01 1b fd e7 dc 0b   ...[.~..........
    0050 - 4b ac 1e ea f9 8c 2f 6c-83 33 c3 45 ce 95 b2 7e   K...../l.3.E...~
    0060 - 9c 51 04 f0 14 9e 0d 03-fb f5 a8 ed 6d b1 90 f3   .Q..........m...
    0070 - 08 3f 47 3b a9 91 f9 d8-99 dc 73 1b a9 86 f6 b0   .?G;......s.....
    0080 - 13 38 30 ae f1 e3 b8 34-7c c2 64 3c 4c ea 8a 10   .80....4|.d<L...
    0090 - 6b e1 59 52 d8 89 f3 9f-6b 17 c7 6c 55 ed 86 0f   k.YR....k..lU...
    00a0 - 70 c6 50 94 21 44 f2 ac-28 f4 ee 59 c3 60 3f f3   p.P.!D..(..Y.`?.
    00b0 - fb f9 bd 54 89 62 44 c5-96 e9 d5 0e 4f be 17 4a   ...T.bD.....O..J

    Start Time: 1291767269
    Timeout   : 300 (sec)
    Verify return code: 21 (unable to verify the first certificate)
---
HEAD / HTTP/1.1
Host: www.narf.ssji.net

HTTP/1.1 200 OK
Date: Wed, 08 Dec 2010 00:15:08 GMT
Server: Apache
Content-Location: index.xhtml
Vary: negotiate
TCN: choice
Content-Type: application/xhtml+xml

It also works for TLS connections.

$ openssl s_client -connect SMTP:587 -starttls smtp
[... certificate details ...]
---
250 XRDST

$ echo | openssl s_client -connect HOST:PORT | sed '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/!d' > HOST.crt
verify error:num=19:self signed certificate in certificate chain
verify return:0
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE----
^D
DONE

The same can be done to get the fingerprint, with some more filtering:

$ echo | openssl s_client -connect HOST:PORT | sed '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/!d' | openssl x509 -fingerprint -noout
^D
verify error:num=19:self signed certificate in certificate chain
verify return:0
DONE
SHA1 Fingerprint=00:11:22:33:44:55:66:77:88:99:AA:BB:CC:DD:EE:FF:00:11:22:33

$ echo | openssl s_client -servername VIRTUALHOST -connect localhost:443 2>/dev/null | grep CN
 0 s:/CN=VIRTUALHOST
   i:/O=CAcert Inc./OU=http://www.CAcert.org/CN=CAcert Class 3 Root
subject=/CN=VIRTUALHOST
issuer=/O=CAcert Inc./OU=http://www.CAcert.org/CN=CAcert Class 3 Root