db.createUser({user:"taobao",pwd:"taobao123", roles:[{role:"readWrite", db:"taobao"}]})，创建了一个taobao库的用户，登录的时候 --authenticationDatabase admin 登录不上，换成--authenticationDatabase taobao就可以，老师的怎么admin就可以登录啊

mongo -u reader -p abc123 --authenticationDatabase admin 上面的命令中, 一定要加上 --authenticationDatabase admin 否则会导致 Authentication failed

老师新年好，身体健康 万事如意 ，，问个小白问题，如果黑客mongo连接进去然后创建个超级用户再登录这种情况怎么办。

这一节其实非常重要，安全是很多人都常常会忽略的一个主题，但又往往是实际工作中很薄弱的一个环节。

生产环境对读写权限分离是非常重要的，一旦有人误使用一些写操作，对生产会带来很大的损失。

唐老师，看了视频中 mongodb 基于证书认证部分，有个疑问：看了mongodb 官方文档也不是太理解，PEMKeyFile 参数官方解释是TLS/SSL证书和密钥PEM文件的路径，clusterFile 参数官方解释x.509成员资格证书和密钥PEM文件的路径。这个两个有什么不同，clusterFile 是指集群中所有节点使用同一个证书吗？如果是，是不是直接挑一个节点进行证书生成，然后拷贝到其他节点上？另外 PEMKeyFile 是不同节点各自的证书吗？

老师createRole失败，麻烦帮忙看一下 2020-03-23T10:45:05.120+0800 F REPL [repl writer worker 6] writer worker caught exception: NamespaceNotFound: Failed to apply operation: { ts: Timestamp(1584931505, 1), t: 34, h: -1891726699602646205, v: 2, op: "i", ns: "admin.system.roles", ui: UUID("591c696f-8201-4b4f-902b-d27447aa8b76"), wall: new Date(1584931505114), o: { _id: "admin.'restoreEx", role: "'restoreEx", db: "admin", privileges: [ { resource: { cluster: true }, actions: [ "addShard" ] }, { resource: { db: "config", collection: "" }, actions: [ "find", "insert", "remove", "update" ] } ], roles: [ { role: "restore", db: "admin" } ] } } :: caused by :: Unable to resolve 591c696f-8201-4b4f-902b-d27447aa8b76 on: { op: "i", ns: "admin.system.roles", ui: UUID("591c696f-8201-4b4f-902b-d27447aa8b76"), o: { _id: "admin.'restoreEx", role: "'restoreEx", db: "admin", privileges: [ { resource: { cluster: true }, actions: [ "addShard" ] }, { resource: { db: "config", collection: "" }, actions: [ "find", "insert", "remove", "update" ] } ], roles: [ { role: "restore", db: "admin" } ] }, ts: Timestamp(1584931505, 1), t: 34, h: -1891726699602646205, v: 2, wall: new Date(1584931505114) } 2020-03-23T10:45:05.120+0800 F - [rsSync-0] Fatal assertion 34437 NamespaceNotFound: Failed to apply operation: { ts: Timestamp(1584931505, 1), t: 34, h: -1891726699602646205, v: 2, op: "i", ns: "admin.system.roles", ui: UUID("591c696f-8201-4b4f-902b-d27447aa8b76"), wall: new Date(1584931505114), o: { _id: "admin.'restoreEx", role: "'restoreEx", db: "admin", privileges: [ { resource: { cluster: true }, actions: [ "addShard" ] }, { resource: { db: "config", collection: "" }, actions: [ "find", "insert", "remove", "update" ] } ], roles: [ { role: "restore", db: "admin" } ] } } :: caused by :: Unable to resolve 591c696f-8201-4b4f-902b-d27447aa8b76 at src/mongo/db/repl/sync_tail.cpp 1016 2020-03-23T10:45:05.120+0800 F - [rsSync-0] ***aborting after fassert() failure