遇到ubuntu@localhost's password:， 不知道密码，很讨厌， 那就免密ssh搞起， 但搞了好几次， ssh免密一直失败，还是提醒ubuntu@localhost's password:， 最后发现是权限的问题， 来看看：
ubuntu@VM-0-15-ubuntu:~$ ssh localhost Warning: Permanently added 'localhost' (ECDSA) to the list of known hosts. ubuntu@localhost's password: Permission denied,please try again. ubuntu@localhost's password: Permission denied,please try again. ubuntu@localhost's password: Permission denied (publickey,password). // 要密码，不知道， 很蛋疼 ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ssh-keygen -t rsa // 一路enter按下去，不要停 Generating public/private rsa key pair. Enter file in which to save the key (/home/ubuntu/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/ubuntu/.ssh/id_rsa. Your public key has been saved in /home/ubuntu/.ssh/id_rsa.pub. The key fingerprint is: SHA256:HuAsdG85+vxn3RLn5QreR9k/CSclzJnimhRTXjPToi8 ubuntu@VM-0-15-ubuntu The key's randomart image is: +---[RSA 2048]----+ | . | | . * . | | . o o = B | | . + o + + * . | | . o S + o o o| | . + + E +.o=| | . o o o.+B+| | o o .oooo*| | o..o. o+.| +----[SHA256]-----+ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ cd .ssh ubuntu@VM-0-15-ubuntu:~/.ssh$ ls id_rsa id_rsa.pub ubuntu@VM-0-15-ubuntu:~/.ssh$ cat id_rsa.pub >> authorized_keys ubuntu@VM-0-15-ubuntu:~/.ssh$ ls authorized_keys id_rsa id_rsa.pub ubuntu@VM-0-15-ubuntu:~/.ssh$ ubuntu@VM-0-15-ubuntu:~/.ssh$ ubuntu@VM-0-15-ubuntu:~/.ssh$ ubuntu@VM-0-15-ubuntu:~/.ssh$ cd .. ubuntu@VM-0-15-ubuntu:~$ chmod 700 .ssh // 必须 ubuntu@VM-0-15-ubuntu:~$ chmod 600 .ssh/* // 必须 ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ssh localhost // 免密进入一层localhost Warning: Permanently added 'localhost' (ECDSA) to the list of known hosts. Welcome to Ubuntu 16.04.1 LTS (GNU/Linux 4.4.0-91-generic x86_64) * Documentation: https://help.ubuntu.com * Management: https://landscape.canonical.com * Support: https://ubuntu.com/advantage Last login: Sat Mar 3 08:51:40 2018 from 222.248.84.42 ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ssh localhost // 免密进入二层localhost Warning: Permanently added 'localhost' (ECDSA) to the list of known hosts. Welcome to Ubuntu 16.04.1 LTS (GNU/Linux 4.4.0-91-generic x86_64) * Documentation: https://help.ubuntu.com * Management: https://landscape.canonical.com * Support: https://ubuntu.com/advantage Last login: Sat Mar 3 08:56:32 2018 from 127.0.0.1 ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ ubuntu@VM-0-15-ubuntu:~$ exit // 退出二层localhost logout Connection to localhost closed. ubuntu@VM-0-15-ubuntu:~$ exit logout Connection to localhost closed. // 退出一层localhost,回归到原来的shell ubuntu@VM-0-15-ubuntu:~$
爬山去了， 多锻炼， 减减肥。
