配置SSH免密

1. 生成公钥、私钥
   ssh-keygen
   会让你输出公钥和私钥的存储地址
   默认公钥在/root/.ssh/id_rsa.pub，私钥在/root/.ssh/id_rsa

2. 复制公钥到远程
   ssh-copy-id -i /root/.ssh/id_rsa.pub root@xxx.xxx.xxx.xxx
   这一行命令是把本端公钥放在追加到远程～/.ssh/authorized_keys文件内

3. 直接登录
   ssh -p 22 root@xxx.xxx.xxx.xxx

配置远程服务器别名

vi ~/.ssh/config
配置文件配置Host别名

#Use only the configured key
IdentitiesOnly=yes
# Add keys to the agent as required on first connection
AddKeysToAgent=yes
# Forward the agent credentials, which allows ssh'ing to nodes your job is running on
ForwardAgent=yes

Host unity
Hostname=unity.uri.edu
User=username_uri_edu
# 这里配置的路径是私钥
IdentityFile=~/.ssh/id_unity

Host andromeda
Hostname=ssh3.hac.uri.edu
User=username
IdentityFile=~/.ssh/id_rsa

配置免密失效的原因及解决方法

原因

• 客户端私钥文件路径未配置或配置错误
• 服务端配置错误
• 权限错误

/etc/ssh/sshd_config 文件配置错误

解决方法
检查客户端 ~/.ssh/config 文件，配置方法如前所述

在服务端修改权限

chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

配置 /etc/ssh/sshd_config 文件，修改以下内容，启用秘钥验证
PubkeyAuthentication yes

修改后重启 sshd 服务

service sshd restart

重启后须重新执行配置拷贝公钥操作

Ref:
https://its.uri.edu/research-computing/advanced-ssh-configuration/
https://blog.csdn.net/sculpta/article/details/108130992