不推荐的免费证书 SSL For Free

SSL For Free 可以免费给网站申请证书，时效是三个月。虽然浏览器可以正常认证该证书，但像 curl、wget 等并不能正常认证，百度蜘蛛也无法正常抓取。

所以，不推荐。可以考虑阿里云提供的免费证书。

SSL For Free 证书：

curl 会出现以下错误：

$ curl -v https://www.icedream.xyz/
*   Trying 23.105.197.234...
* Connected to www.icedream.xyz (23.105.197.234) port 443 (#0)
* found 148 certificates in /etc/ssl/certs/ca-certificates.crt
* found 592 certificates in /etc/ssl/certs
* ALPN, offering http/1.1
* SSL connection using TLS1.2 / ECDHE_RSA_AES_128_GCM_SHA256
* server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none
* Closing connection 0
curl: (60) server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none
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.

百度蜘蛛会出现以下错误：

以下是百度Spider抓取结果及页面信息：

提交网址：	http://192.168.3.115:9088
抓取网址：	http://192.168.3.115:9088
抓取UA：	Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)
抓取时间：	2020-01-05 10:11:04
网站IP：	23.***.***.234 报错
下载时长：	3.008秒
抓取异常信息：	socket 读写错误  查看帮助