报的错误：
[root@localhost ~]# npm install -g cnpm --registry=https://registry.npm.taobao.org
npm ERR! code CERT_NOT_YET_VALID
npm ERR! errno CERT_NOT_YET_VALID
npm ERR! request to https://registry.npm.taobao.org/cnpm failed, reason: certificate is not yet valid
npm ERR! A complete log of this run can be found in:
npm ERR! /root/.npm/_logs/2006-01-23T01_49_05_762Z-debug.log
解决：
同步ntp:
ntpdate 172.16.2.26
