设置ssh证书登录，禁止root登录，禁止su到root，sudo权限设置

useradd newuser
passwd newuser

vim /etc/ssh/sshd_config

PermitRootLogin no
RSAAuthentication yes
PubkeyAuthentication yes
PasswordAuthentication no
ClientAliveInterval 30
ClientAliveCountMax 5

二、禁止su

vim /etc/pam.d/su
auth            required        pam_wheel.so use_uid

vim /etc/login.defs
SU_WHEEL_ONLY yes

三、sudo权限设置

chmod 640 /etc/sudoers
vim /etc/sudoers
lity    ALL=(ALL)       ALL
chmod 440 /etc/sudoers