1. 查看curl版本
在phpinfo中，可以查看
curl
| cURL support | enabled |
| cURL Information | 7.35.0 |
| Age | 3 |
| Features | |
| AsynchDNS | Yes |
| Debug | No |
| GSS-Negotiate | Yes |
| IDN | No |
| IPv6 | Yes |
| Largefile | Yes |
| NTLM | Yes |
| SPNEGO | Yes |
| SSL | Yes |
| SSPI | Yes |
| krb4 | No |
| libz | Yes |
| CharConv | No |
| Protocols | dict, file, ftp, ftps, gopher, http, https, imap, imaps, ldap, pop3, pop3s, rtsp, scp, sftp, smtp, smtps, telnet, tftp |
| Host | i386-pc-win32 |
| SSL Version | OpenSSL/0.9.8{ |
| ZLib Version | 1.2.7 |
| libSSH Version | libssh2/1.4.2 |
1. ssl version对应的数字
CURL_SSLVERSION_DEFAULT (0)
CURL_SSLVERSION_TLSv1 (1)
CURL_SSLVERSION_SSLv2 (2)
CURL_SSLVERSION_SSLv3 (3)
CURL_SSLVERSION_TLSv1_0 (4)
CURL_SSLVERSION_TLSv1_1 (5)
CURL_SSLVERSION_TLSv1_2 (6)
2. 检测ssl兼容性的网站
https://www.ssllabs.com/ssltest/