Mozilla、思科、Akamai、IdenTrust、EFF 和密歇根大学研究人员联合宣布了 Let’s Encrypt CA 项
目，计划为网站提供免费的基本 SSL 证书，以加速互联网从 HTTP 向 HTTPS 过渡。Let’s Encrypt CA 将由非赢利组织
Internet Security Research Group (ISRG) 运营，今天12月4日凌晨项目正式进入公测阶段，遂赶紧进行申请试用一下。
之前我申请证书都是用BS方式，这次是CS方式，感觉挺新鲜。
我的服务器环境 centos6.6
要安装python2.7，2.6在申请时会报错
下载地址 https://www.python.org/downloads/release/python-2710/
wget
tar zxf Python-2.7.10.tgz
cd Python-2.7.10
./configure
make && make install
#把系统python命令指到新版本
which python
/usr/local/bin/python
rm /usr/local/bin/python
ln -s /usr/local/bin/python2.7 /usr/local/bin/python
2.下载letsencrypt客户端
yum install -y git
git clone https://github.com/letsencrypt/letsencrypt.git
cd letsencrypt
./letsencrypt-auto --help
Updating letsencrypt and virtual environment dependencies.......
Running with virtualenv: /root/.local/share/letsencrypt/bin/letsencrypt --help
letsencrypt [SUBCOMMAND] [options] [-d domain] [-d domain] ...
The Let's Encrypt agent can obtain and install HTTPS/TLS/SSL certificates. By
default, it will attempt to use a webserver both for obtaining and installing
the cert. Major SUBCOMMANDS are:
(default) run Obtain & install a cert in your current webserver
certonly Obtain cert, but do not install it (aka "auth")
install Install a previously obtained cert in a server
revoke Revoke a previously obtained certificate
rollback Rollback server configuration changes made during install
config_changes Show changes made to server config during installation
plugins Display information about installed plugins
Choice of server plugins for obtaining and installing cert:
--apache Use the Apache plugin for authentication & installation
--standalone Run a standalone webserver for authentication
(nginx support is experimental, buggy, and not installed by default)
--webroot Place files in a server's webroot folder for authentication
OR use different plugins to obtain (authenticate) the cert and then install it:
--authenticator standalone --installer apache
More detailed help:
-h, --help [topic] print this message, or detailed help on a topic;
the available topics are:
all, automation, paths, security, testing, or any of the subcommands or
plugins (certonly, install, nginx, apache, standalone, webroot, etc)
3.客户端可以为你提供申请+全自动安装apache/nginx等一条龙服务，这里我选择DIY，只申请，不用麻烦客户端了，执行以下命令
./letsencrypt-auto certonly --manual
输入你的域名
提示是否同意他们记录你这次请求的ip地址，同意
这一步是验证域名所有权，很关键
这一步的意思是，客户端将访问http://www.example.com/.well-known/acme-challenge/xiDWA8FkdWeTua7MIXBpQ3PeLt8jVu5Eimi4-jPsTHs 看看输出是不是 xiDWA8FkdWeTua7MIXBpQ3PeLt8jVu5Eimi4-jPsTHs.MOcybE5RrQ_NsGgFybrHkVcTSohWn2z0JDfTtQkHKQE
我是提前装了nginx服务器，那么只需要在我的网站根目录下创建目录和对应内容的文件，在公网能访问得到就可以了。
cd /wwwroot/
mkdir -p ./.well-known/acme-challenge/
echo xiDWA8FkdWeTua7MIXBpQ3PeLt8jVu5Eimi4-jPsTHs.MOcybE5RrQ_NsGgFybrHkVcTSohWn2z0JDfTtQkHKQE>./.well-known/acme-challenge/xiDWA8FkdWeTua7MIXBpQ3PeLt8jVu5Eimi4-jPsTHs
试试获取一下输出正常了没
curl
若正常，按回车。（如果还没装web服务器的话可以按照提示执行#run only once per server下面的命令）
4.证书获取成功
IMPORTANT NOTES:
- Congratulations! Your certificate and chain have been saved at
/etc/letsencrypt/live/example.com/fullchain.pem. Your cert will
expire on 2016-03-03. To obtain a new version of the certificate in
the future, simply run Let's Encrypt again.
- If like Let's Encrypt, please consider supporting our work by:
Donating to ISRG / Let's Encrypt: https://letsencrypt.org/donate
Donating to EFF: https://eff.org/donate-le
后面再发一篇博文讲述如何使用这个证书。