A免密登陆B
A
cd /root/.ssh
ssh-keygen -t rsa
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
B
#将A的id_rsa.pub公钥文件写入B的authorized_keys
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
A
#需要A的known_hosts文件写入权限
#A可以免密登陆B，第一次登陆需要确认，并将连接B的信息写入known_hosts