没有管理员用户的话就先建一个

# /usr/local/mongodb/bin/mongo --host localhost --port 27017

rs:PRIMARY> use admin
switched to db admin
rs:PRIMARY> db.createUser({
...    "user": "root", 
...    "pwd": "密码", 
...    "roles": [
...            {
...                    "role": "userAdminAnyDatabase", 
...                    "db": "admin"
...            }, 
...            {
...                    "role": "readWriteAnyDatabase", 
...                    "db": "admin"
...            }, 
...            {
...                    "role": "dbAdmin", 
...                    "db": "admin"
...            }, 
...            {
...                    "role": "root", 
...                    "db": "admin"
...            }
...    ]
... });

生成协同文件传输到集群每个节点

# openssl rand -base64 512 > /usr/local/mongodb/access.key
# chmod 0600 /usr/local/mongodb/access.key

修改配置文件

cat >> /usr/local/mongodb/mongod.conf << EOF
auth=true
keyFile=/usr/local/mongodb/access.key
EOF

重启MongoDB

root用户登录验证

# /usr/local/mongodb/bin/mongo localhost:27017/admin -u root -p

添加普通用户

rs:PRIMARY> use 库名
rs:PRIMARY> db.createUser({
...  user:"用户名",
...  pwd:"密码",
...  roles:[
...   {role:"readWrite",db:"库名"}
...  ]
... });