さくらVPSのCentos7にMongoDBをインストールしてユーザー認証までしたい。

$systemctl start mongod.service
$mongo
>use admin
>db.createUser(...)

$systemctl stop mongod.service
$vim /etc/mongod.conf

#以下を変更しました。
#security:
↓
security:
    authorization: enabled

$systemctl start mongod.service
Job for mongod.service failed because the control process exited with error code. See "systemctl status mongod.service" and "journalctl -xe" for details.

$mongod --port 27017 --dbpath /var/lib/mongodb
{"t":{"$date":"2021-03-03T18:00:53.439+09:00"},"s":"I",  "c":"CONTROL",  "id":23285,   "ctx":"main","msg":"Automatically disabling TLS 1.0, to force-enable TLS 1.0 specify --sslDisabledProtocols 'none'"}
{"t":{"$date":"2021-03-03T18:00:53.445+09:00"},"s":"W",  "c":"ASIO",     "id":22601,   "ctx":"main","msg":"No TransportLayer configured during NetworkInterface startup"}
{"t":{"$date":"2021-03-03T18:00:53.445+09:00"},"s":"I",  "c":"NETWORK",  "id":4648601, "ctx":"main","msg":"Implicit TCP FastOpen unavailable. If TCP FastOpen is required, set tcpFastOpenServer, tcpFastOpenClient, and tcpFastOpenQueueSize."}
{"t":{"$date":"2021-03-03T18:00:53.446+09:00"},"s":"I",  "c":"STORAGE",  "id":4615611, "ctx":"initandlisten","msg":"MongoDB starting","attr":{"pid":1365,"port":27017,"dbPath":"/var/lib/mongodb","architecture":"64-bit","host":"os3-360-13185.vs.sakura.ne.jp"}}
{"t":{"$date":"2021-03-03T18:00:53.446+09:00"},"s":"I",  "c":"CONTROL",  "id":23403,   "ctx":"initandlisten","msg":"Build Info","attr":{"buildInfo":{"version":"4.4.4","gitVersion":"8db30a63db1a9d84bdcad0c83369623f708e0397","openSSLVersion":"OpenSSL 1.0.1e-fips 11 Feb 2013","modules":[],"allocator":"tcmalloc","environment":{"distmod":"rhel70","distarch":"x86_64","target_arch":"x86_64"}}}}
{"t":{"$date":"2021-03-03T18:00:53.446+09:00"},"s":"I",  "c":"CONTROL",  "id":51765,   "ctx":"initandlisten","msg":"Operating System","attr":{"os":{"name":"CentOS Linux release 7.8.2003 (Core)","version":"Kernel 3.10.0-1127.8.2.el7.x86_64"}}}
{"t":{"$date":"2021-03-03T18:00:53.446+09:00"},"s":"I",  "c":"CONTROL",  "id":21951,   "ctx":"initandlisten","msg":"Options set by command line","attr":{"options":{"net":{"port":27017},"storage":{"dbPath":"/var/lib/mongodb"}}}}
{"t":{"$date":"2021-03-03T18:00:53.447+09:00"},"s":"E",  "c":"STORAGE",  "id":20568,   "ctx":"initandlisten","msg":"Error setting up listener","attr":{"error":{"code":9001,"codeName":"SocketException","errmsg":"Address already in use"}}}
{"t":{"$date":"2021-03-03T18:00:53.447+09:00"},"s":"I",  "c":"REPL",     "id":4784900, "ctx":"initandlisten","msg":"Stepping down the ReplicationCoordinator for shutdown","attr":{"waitTimeMillis":10000}}
{"t":{"$date":"2021-03-03T18:00:53.447+09:00"},"s":"I",  "c":"COMMAND",  "id":4784901, "ctx":"initandlisten","msg":"Shutting down the MirrorMaestro"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"SHARDING", "id":4784902, "ctx":"initandlisten","msg":"Shutting down the WaitForMajorityService"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"NETWORK",  "id":4784905, "ctx":"initandlisten","msg":"Shutting down the global connection pool"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"NETWORK",  "id":4784918, "ctx":"initandlisten","msg":"Shutting down the ReplicaSetMonitor"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"SHARDING", "id":4784921, "ctx":"initandlisten","msg":"Shutting down the MigrationUtilExecutor"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"CONTROL",  "id":4784925, "ctx":"initandlisten","msg":"Shutting down free monitoring"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"STORAGE",  "id":4784927, "ctx":"initandlisten","msg":"Shutting down the HealthLog"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"STORAGE",  "id":4784929, "ctx":"initandlisten","msg":"Acquiring the global lock for shutdown"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"-",        "id":4784931, "ctx":"initandlisten","msg":"Dropping the scope cache for shutdown"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"FTDC",     "id":4784926, "ctx":"initandlisten","msg":"Shutting down full-time data capture"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"CONTROL",  "id":20565,   "ctx":"initandlisten","msg":"Now exiting"}
{"t":{"$date":"2021-03-03T18:00:53.448+09:00"},"s":"I",  "c":"CONTROL",  "id":23138,   "ctx":"initandlisten","msg":"Shutting down","attr":{"exitCode":48}}

$mongo
MongoDB shell version v4.4.4
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused :
connect@src/mongo/shell/mongo.js:374:17
@(connect):2:6
exception: connect failed
exiting with code 1