mongodb分为管理员用户和普通用户，并且还有个验证库，建立用户时use到的库（验证库），信息就存储在admin数据库下。

在使用用户时，要加上验证库才能登录，对于管理员用户，必须在admin下创建，验证用户返回值为1即成功。

1、创建管理员用户

语法：
user：用户名
pwd：密码
roles：
    role：角色名
    db：作用对象

常用role：root、readWrite、read

> use admin
switched to db admin
> db.createUser({
... user:"root",
... pwd:"yy123456",
... roles:[{role:"root",db:"admin"}]
... }
... )
Successfully added user: {
    "user" : "root",
    "roles" : [
        {
            "role" : "root",
            "db" : "admin"
        }
    ]
}
> db.auth('root','yy123456')
1
> 

> db.createUser({user:"root",pwd:"yy123456",roles:[{role:"root",db:"admin"}]})

2、创建普通用户

> use test
switched to db test
> db.createUser({
... user:"test_1",
... pwd:"123456",
... roles:[{role:"readWrite",db:"test"}]
... })
Successfully added user: {
    "user" : "test_1",
    "roles" : [
        {
            "role" : "readWrite",
            "db" : "test"
        }
    ]
}

　> db.auth('test_1','123456')
　1
　>

3、登录

#本地登录
mongo -uroot -pyy123456 admin
mongo -utest_1 -p123456 test

#远程登录
mongo -uroot -pyy123456 ip+端口/admin
mongo -utest_1 -p123456 ip+端口/test

4、删除用户

　以root用户登录，删除后use到admin库，查看所用用户信息

> use test
switched to db test
> db.dropUser("test_1")
true
> db.auth('test_1','123456')
Error: Authentication failed.
0
> use admin
switched to db admin
> db.system.users.find().pretty()
{
    "_id" : "admin.root",
    "userId" : UUID("31cc514b-00b2-434b-8d78-2dcd450f3cf2"),
    "user" : "root",
    "db" : "admin",
    "credentials" : {
        "SCRAM-SHA-1" : {
            "iterationCount" : 10000,
            "salt" : "WVVZcAR1PnSjQLTAMolnYA==",
            "storedKey" : "m5P8eMDZ7NvmpjAYH8FGTO6+k9k=",
            "serverKey" : "B1mD3dfNpvlza7eO5g80MovmUaA="
        },
        "SCRAM-SHA-256" : {
            "iterationCount" : 15000,
            "salt" : "eivTZLkntjrnQllzhE8uUHCWtNdVpcvMT8Pysg==",
            "storedKey" : "9NjJIph+k4WOnC+Fa/Th1LIzRbItK/R33EOZX8DC3+0=",
            "serverKey" : "eF3eieOZvDEzQ0fMZlnOy1q0zXSwcD/5FeTzM7jIbFM="
        }
    },
    "roles" : [
        {
            "role" : "root",
            "db" : "admin"
        }
    ]
}
>

5、用户权限