curl:出现SSL错误提示

在上一篇博文中，升级ruby版本中，提示如下错误：

1） Error fetching https://mirrors.aliyun.com/rubygems/:

[root@web ~]# gem sources -a https://mirrors.aliyun.com/rubygems/
Error fetching https://mirrors.aliyun.com/rubygems/:
        SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed (https://mirrors.aliyun.com/rubygems/specs.4.8.gz)

2）curl: (60) Peer certificate cannot be authenticated with known CA certificates

[root@web ~]# \curl -sSL https://get.rvm.io | bash -s stable
curl: (60) Peer certificate cannot be authenticated with known CA certificates
More details here: http://curl.haxx.se/docs/sslcerts.html

curl performs SSL certificate verification by default, using a "bundle"
 of Certificate Authority (CA) public keys (CA certs). If the default
 bundle file isn't adequate, you can specify an alternate file
 using the --cacert option.
If this HTTPS server uses a certificate signed by a CA represented in
 the bundle, the certificate verification probably failed due to a
 problem with the certificate (it might be expired, or the name might
 not match the domain name in the URL).
If you'd like to turn off curl's verification of the certificate, use
 the -k (or --insecure) option.

上述错误是主机时间不对。更改过主机时间后，可避免上述错误。