Linux – Easy Way to Check SSL Cipher Preference from Command-Line

centoslinuxSecurityssl

CentOS 5.x

I want to confirm which SSL ciphers are supported and preferred on my web server. Is there an easy way to do this WITHOUT using third-party audit software/equipment? I was hoping for something in openssl. Unfortunately, the web server is locked down so other third-party online tools like Qualys SSL Test won't work.

Best Answer

Currently, I believe the only way to do this is to manually check the different ciphers with openssl s_client.

Preferred ciphers are easy enough, just connect with no -cipher option and the cipher that's used is likely the server's preferred (as long as it's in openssl's default cipher list).

Auditing what ciphers are supported is more legwork, as you'll need to manually specify each cipher that you want to test with the -cipher option (openssl ciphers will show you your options) and see if you can connect. There is an outstanding feature request against OpenSSL to add cipher discovery for this purpose, but that's of no help at the moment.

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