Added Setup guide for Unifi using external mongodb database

Linux/Docs/Setup-Unifi-With-External-Database.md

@@ -0,0 +1,80 @@
+## Setup MongoDB server
+Install MongoDB the normal way
+[Official documentation](https://www.mongodb.com/docs/v4.4/tutorial/install-mongodb-on-debian/).
+
+
+**Create admin user for MongoDB**  
+Enter MongoDB shell using `mongo`  
+and use the following command 
+```
+use admin
+db.createUser(
+  {
+    user: "root",
+    pwd: passwordPrompt(),
+    roles: ["userAdminAnyDatabase", "dbAdminAnyDatabase", "readWriteAnyDatabase"],
+    authenticationRestrictions: [ { clientSource: [ "127.0.0.1" ] } ]
+  }
+)
+exit
+```
+**Stop MongoDB server**  
+```
+systemctl stop mongod
+```
+
+**Update mongod config**  
+update the following items in `/etc/mongod.conf`
+```
+net:
+  bindIp: 0.0.0.0
+
+security:
+  authorization: enabled
+  clusterIpSourceWhitelist:
+    - 127.0.0.1
+    - ::1
+```
+
+**Start MongoDB server**  
+```
+systemctl start mongod
+```
+
+**Add MongoDB user for Unifi DB**  
+
+Enter MongoDB shell using `mongo -u root`  
+and use the following command, make sure to update the ip before running the commmand
+```
+db.getSiblingDB("Unifi").createUser({user: "Unifi", pwd: passwordPrompt(), roles: [{role: "dbOwner", db: "Unifi"},{role: "dbOwner", db: "Unifi_stat"}],authenticationRestrictions: [ { clientSource: [ "<UnifiIP>" ] } ]});
+```
+
+## Setup Unifi server
+
+**Install dummy mongodb-server**  
+the dummy package is created as `.deb` with equivs,  
+and can be installed using dpkg
+
+Content of `mongodb-org-server.equivs`
+
+```
+Package: mongodb-org-server
+Version: 4.4.28
+Maintainer: PKG Builder <Mailer@localhost>
+Architecture: all
+Description: Dummy MongoDB database server
+ A dummy package so that Unifi will install without MongoDB locally installed
+
+```
+
+**Setup Unifi server**  
+Install Unfi the normal way
+[Official documentation](https://help.ui.com/hc/en-us/articles/220066768-Updating-and-Installing-Self-Hosted-UniFi-Network-Servers-Linux).
+
+Add the following to `/usr/lib/Unifi/data/system.properties`
+```
+db.mongo.local=false
+db.mongo.uri=mongodb://Unifi:<UnifiDBPassword>@27017:PORT/Unifi
+statdb.mongo.uri=mongodb://Unifi:<UnifiDBPassword>@27017:PORT/Unifi_stat
+Unifi.db.name=Unifi
+```