Please check the free script written by the firm where one of the highly qualified folks at Security SE works: https://labs.portcullis.co.uk/tools/ssl-cipher-suite-enum/
ssl-cipher-suite-enum identifies the following common security issues relating to SSL: ...Support of key exchange algorithms that don’t support forward secrecy – or equivalently, cipher suites that allow sniffed traffic to be retrospectively decrypted if the private SSL key were to be compromised.
If you want to do it slowly and by hand, openssl
portmanteau toolset is very handy:
From https://community.qualys.com/thread/12193:
openssl s_client -starttls smtp -crlf -connect YOUR_SMTP_SERVER:25
If you see DHE (Diffie-Hellmann Ephemeral) in the cipher suite, it's PFS.
From this post at Security SE
TLS_DHE_DSS_WITH_DES_CBC_SHA DHE-DSS-CBC-SHA
TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA DHE-DSS-DES-CBC3-SHA
TLS_DHE_RSA_WITH_DES_CBC_SHA DHE-RSA-DES-CBC-SHA
TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA DHE-RSA-DES-CBC3-SHA
TLS_DHE_DSS_WITH_AES_128_CBC_SHA DHE-DSS-AES128-SHA
TLS_DHE_DSS_WITH_AES_256_CBC_SHA DHE-DSS-AES256-SHA
TLS_DHE_RSA_WITH_AES_128_CBC_SHA DHE-RSA-AES128-SHA
TLS_DHE_RSA_WITH_AES_256_CBC_SHA DHE-RSA-AES256-SHA
TLS_DHE_DSS_WITH_CAMELLIA_128_CBC_SHA DHE-DSS-CAMELLIA128-SHA
TLS_DHE_DSS_WITH_CAMELLIA_256_CBC_SHA DHE-DSS-CAMELLIA256-SHA
TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA DHE-RSA-CAMELLIA128-SHA
TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA DHE-RSA-CAMELLIA256-SHA
TLS_DHE_DSS_WITH_SEED_CBC_SHA DHE-DSS-SEED-SHA
TLS_DHE_RSA_WITH_SEED_CBC_SHA DHE-RSA-SEED-SHA
If we include the Elliptic Curve ciphers, the following also implement PFS:
TLS_ECDHE_RSA_WITH_NULL_SHA ECDHE-RSA-NULL-SHA
TLS_ECDHE_RSA_WITH_RC4_128_SHA ECDHE-RSA-RC4-SHA
TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA ECDHE-RSA-DES-CBC3-SHA
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA ECDHE-RSA-AES128-SHA
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA ECDHE-RSA-AES256-SHA
TLS_ECDHE_ECDSA_WITH_NULL_SHA ECDHE-ECDSA-NULL-SHA
TLS_ECDHE_ECDSA_WITH_RC4_128_SHA ECDHE-ECDSA-RC4-SHA
TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA ECDHE-ECDSA-DES-CBC3-SHA
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA ECDHE-ECDSA-AES128-SHA
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA ECDHE-ECDSA-AES256-SHA
If you also want to include TLS 1.2 (note that there are no TLS 1.1 specific suites) then you can expand the list to include:
TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 DHE-RSA-AES128-SHA256
TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 DHE-RSA-AES256-SHA256
TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 DHE-RSA-AES128-GCM-SHA256
TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 DHE-RSA-AES256-GCM-SHA384
TLS_DHE_DSS_WITH_AES_128_CBC_SHA256 DHE-DSS-AES128-SHA256
TLS_DHE_DSS_WITH_AES_256_CBC_SHA256 DHE-DSS-AES256-SHA256
TLS_DHE_DSS_WITH_AES_128_GCM_SHA256 DHE-DSS-AES128-GCM-SHA256
TLS_DHE_DSS_WITH_AES_256_GCM_SHA384 DHE-DSS-AES256-GCM-SHA384
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 ECDHE-RSA-AES128-SHA256
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 ECDHE-RSA-AES256-SHA384
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 ECDHE-RSA-AES128-GCM-SHA256
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 ECDHE-RSA-AES256-GCM-SHA384
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 ECDHE-ECDSA-AES128-SHA256
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 ECDHE-ECDSA-AES256-SHA384
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 ECDHE-ECDSA-AES128-GCM-SHA256
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 ECDHE-ECDSA-AES256-GCM-SHA384
TLS_ECDHE_ECDSA_WITH_CAMELLIA_128_CBC_SHA256 ECDHE-ECDSA-CAMELLIA128-SHA256
TLS_ECDHE_ECDSA_WITH_CAMELLIA_256_CBC_SHA384 ECDHE-ECDSA-CAMELLIA256-SHA384
TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256 ECDHE-RSA-CAMELLIA128-SHA256
TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384 ECDHE-RSA-CAMELLIA256-SHA384