如何获取自己的公网IP呢？
1. dig查google dns
dig TXT +short o-o.myaddr.l.google.com @ns1.google.com
#或
dig +short myip.opendns.com @resolver1.opendns.com
2. curl查IP网站
curl icanhazip.com
curl ifconfig.me
curl icanhazip.com
curl ipecho.net/plain
curl ifconfig.co
3. 参考
http://www.chenshake.com/page/2/
https://www.cyberciti.biz/faq/how-to-find-my-public-ip-address-from-command-line-on-a-linux/