1.以非auth认证方式启动数据库：
[mongodb@hadoop1 ~]$ mongod --dbpath=/mongodb/data --logpath=/mongodb/log/trace.log --logappend  --port=27017 --fork
[mongodb@hadoop1 ~]$ mongo
MongoDB shell version: 3.2.4
connecting to: test
> show dbs
local  0.000GB      #当前只有一个local库，admin库是不存在的
> 2.在指定的数据库下创建用户
> use admin         #帐号是跟着库走的，所以要在指定库里创建用户，必须也在指定库里验证(auth)
switched to db admin
> db.createUser(
...    {
...  user: "dba",
...  pwd: "dba",
...  roles: [ { role: "userAdminAnyDatabase", db: "admin" } ]
...    }
... );
> user： 用户名
pwd：  密码
roles：指定用户的角色，可以用一个空数组给新用户设定空角色；在roles字段,可以指
定内置角色和用户定义的角色。 role里的角色 可以选：Built-In Roles（内置角色）：
1. 数据库用户角色：read、readWrite;
2. 数据库管理角色：dbAdmin、dbOwner、userAdmin；
3. 集群管理角色：clusterAdmin、clusterManager、clusterMonitor、hostManager；
4. 备份恢复角色：backup、restore；
5. 所有数据库角色：readAnyDatabase、readWriteAnyDatabase，userAdminAnyDatabase、dbAdminAnyDatabase
6. 超级用户角色：root
7. 内部角色：__system

[mongodb@hadoop1 ~]$ mongod --dbpath=/mongodb/data --logpath=/mongodb/log/trace.log --logappend  --auth --port=27017 --fork
[mongodb@hadoop1 ~]$ mongo
MongoDB shell version: 3.2.4
connecting to: test
> use admin               #因为是在admin下面添加的帐号，所以要到admin下面验证(连接)。
switched to db admin
> show dbs;
2016-03-27T10:44:27.039-0400 E QUERY    [thread1] Error: listDatabases failed:{"ok" : 0,"errmsg" : "not authorized on admin to execute command { listDatabases: 1.0 }","code" : 13
} > db.auth('dba','dba');   #相当于输入用户名/密码验证(连接)
1
> show dbs;
admin  0.000GB
local  0.000GB
>

> use admin
> db.auth('dba','dba');
> use test                #切换到test数据库，这两个用户是在test下创建的
switched to db test
> db.createUser(
...  {
...    user: "polestar",
...    pwd: "polestar",
...    roles: [{ role: "read", db: "test" }]
...  }
... )
> db.createUser(
...  {
...    user: "polestar_rw",
...    pwd: "polestar",
...    roles: [ { role: "readWrite", db: "test" }]
...  }
... );
> > show users;            #test数据库下只有两个用户
{"_id" : "test.polestar","user" : "polestar","db" : "test","roles" : [{"role" : "read","db" : "test"}]
}
{"_id" : "test.polestar_rw","user" : "polestar_rw","db" : "test","roles" : [{"role" : "readWrite","db" : "test"}]
}
>
> use admin;           #admin数据库下只有一个用户
switched to db admin
> show users;
{"_id" : "admin.dba","user" : "dba","db" : "admin","roles" : [{"role" : "userAdminAnyDatabase","db" : "admin"}]
}
>

> use admin;
switched to db admin
> db.auth('dba','dba')
1
> db.createUser(
...   {
... user: "root",
... pwd: "root",
... roles: [{ role: "root", db: "admin" }]
...   }
... )
> > db.auth('root','root')         #超级用户可以垮裤插入、查询
1
> use test
switched to db test
> db.abc.insert({"a":1,"b":2})
WriteResult({ "nInserted" : 1 })
> db.abc.find()
{ "_id" : ObjectId("56f7fa72a219e00610fe75cb"), "a" : 1, "b" : 2 }
> 

> use admin
switched to db admin
> db.createUser(
...   {
... user: "mgdb",
... pwd: "mgdb",
... roles: [{ role: "readWrite", db: "test" }]  #在admin库下创建test库的帐号
...   }
... )
>> show users;
{"_id" : "admin.dba","user" : "dba","db" : "admin","roles" : [{"role" : "userAdminAnyDatabase","db" : "admin"}]
}
{"_id" : "admin.root","user" : "root","db" : "admin","roles" : [{"role" : "root","db" : "admin"}]
}
{"_id" : "admin.mgdb","user" : "mgdb","db" : "admin","roles" : [{"role" : "readWrite","db" : "test"}]
}
> > use test
switched to db test
> db.auth('mgdb','mgdb');
Error: Authentication failed.    #在admin下创建的帐号，不能直接在其他库验证，
0
> use admin                      #只能在帐号创建库下认证，再去其他库进行操作
switched to db admin
> db.auth('mgdb','mgdb');
1
> use test
switched to db test
> db.abc.insert({"a":1111,"b":2222})
WriteResult({ "nInserted" : 1 })
>