How To Change MongoDB Default And Connect With MongoDB

The MongoDB protocol is a simple socket-based, request-response style protocol. Connection with the client and Database server happens through a regular TCP/IP socket.

MongoDB uses TCP as its transport layer protocol. The predefined default port for connection is 27017.

Connection URL:

List of default MongoDB ports

The following table lists the default TCP ports used by MongoDB

Checkout MongoDB Interview Questions

How to change MongoDB default port

You can also change the default MongoDB port from 27017 to any port of your choice (make sure that no other application is using that port).

Method 1

1. Start MongoDB server with – port argument
Open command prompt as administrator, navigate to MongoDB installation directory’s bin folder then type mongod --dbpath "C:Datadb" --port 20000
You will see waiting for a connection on port 20000

2. Open another instance of command prompt as administrator, navigate to MongoDB installation directory’s bin folder then type mongo --port 20000
The connection will be established.

Method 2

1. Create a configuration file “mongod.conf”. The configuration file is in YAML format.
2. Run with flag --config location to a configuration file. e.g. mongod --config /etc/mongod.conf

Example configuration file

systemLog:
 destination: file
  path: "/mongodb/log/mongod.log"
  logAppend: true
storage:
  journal:
     enabled: true
processManagement:
  fork: true
net:
  bindIp: 127.0.0.1
  port: 20000
setParameter:
  enableLocalhostAuthBypass: false

Notice that port number changed to 20000.

On mongo shell type db.runCommand({whatsmyuri : 1}). It will show the IP and port number the server is listening to.

Checkout MongoDB Tutorial

Connect to MongoDB

Please follow the steps to connect to the MongoDB.

1. Go to the MongoDB installation directory and navigate to the bin folder. Launch mongod.exe. You can also do this from a command prompt. This is the MongoDB server. You must have a Datadb directory defined for MongoDB.

2. Launch mongo.exe. This is the mongo client. You can do this from a command prompt but launch another instance. Please use run as administrator for both. Mongo.exe will open the MongoDB shell.

3. MongoDB also provides drivers for different programming languages.

Example 1 JavaScript

var mongo = require('mongodb');
var MongoClient = mongo.MongoClient;   
MongoClient.connect('mongodb://'dbusername':'dbpassword'@'dbhost':'dbport'/'dbname,function(err, db)
{ 
    if(err)
       console.log(err);
     else
     {
       console.log('Mongo Connected....');
     }
}

Checkout MongoDB Interview Questions

Example 2 C++

#include
#include
#include "mongo/client/dbclient.h"
void run() {
 mongo::DBClientConnection c;
 c.connect("localhost");
}
int main()
{
 try
{
   run();
   std::cout << "connected ok" << std::endl;
 } catch( const mongo::DBException &e )
{
   std::cout << "caught " << e.what() << std::endl;
 }
 return EXIT_SUCCESS;
}