root 用户无法登陆

修改/etc/ssh/sshd_config 中的PermitRootLogin yes

#PermitRootLogin prohibit-password
#PermitEmptyPasswords no
# the setting of "PermitRootLogin without-password".
PermitRootLogin yes
#PermitTTY yes
#PermitUserEnvironment no
#PermitTunnel no
#       PermitTTY no

保存后，然后重启ssh server
service sshd restart