Dineshprabu S dineshsprabu

Building something you might find useful :)

dineshsprabu / check_mxrecord_nodejs.js

Created January 29, 2016 09:16

Check MX Record for domains

	/* npm install dns */
	var dns = require('dns');

	/* domain name to check for record */
	domain_name = '<domain-name>';

	/* dns.resolveMx can do the job for us */
	dns.resolveMx(domain_name, function(err, addresses){
	if(err){ return console.log(err.stack);}
	console.log(addresses);

dineshsprabu / first_letter_to_upper_case.js

Created February 2, 2016 09:50

Changing First Letter of a String to Upper Case in Javascript

	/* Changing first letter of string to uppercase */
	String.prototype.toFirstUpperCase = function(){
	return this.slice(0,1).toUpperCase()+this.slice(1);
	}

	/* Usage */
	"example".toFirstUpperCase(); //Example

dineshsprabu / iptable_rule_allow_ssh_deny_all.txt

Last active February 3, 2016 09:03

IPTable Rule for Allowing SSH and Denying all other ports

	/* iptable rule for droping connections through eth0 to all ports except 22(ssh) */

	>> iptables -A INPUT -i eth0 -p tcp ! --dport 22 -j DROP

	/* Check applied rule */

	>> iptables -L

	target prot opt source destination
	DROP tcp -- anywhere anywhere tcp dpt:!ssh

dineshsprabu / nginx_load_balancing_steps.txt

Created February 3, 2016 16:44

Configuring NGINX Load Balancing

	/* install nginx */
	>>sudo apt-get install nginx

	/* comment out other line and add configurations to the below file */
	>>sudo vi /etc/nginx/sites-available/default


	/* list of server to be added to upstream */
	upstream backend {
	server <IPADDRESS1>:<PORT>;

dineshsprabu / mysql_query_email_inside_angular_braces.txt

Last active February 5, 2016 08:08

MySQL query to extract email id inside angular braces < >

select replace(substring(`email_field`, LOCATE('<', `email_field`)+1),substring(`email_field`, LOCATE('>', `email_field`)),'') from table_name

dineshsprabu / solution_mongodb_cannot_read_property_undefined.txt

Created February 8, 2016 04:52

[Solution] "Cannot read property 'name' of undefined"

	/* installing below version of mongodb can fix the problem for now */

	npm install [email protected]

	/* for package.json, make an entry as below */

	"mongodb":"^1.4.x"

dineshsprabu / connect_mongodb_monk_nodejs.js

Created February 8, 2016 05:02

Connecting to MongoDB using Monk from NodeJS

	var mongo = require('mongodb');
	var monk = require('monk');

	var db_name = ''
	var db = monk('localhost:27017/'+db_name);

	var collection = db.get('collection_name');
	collection.find({}, function(err,docs){
	console.log(docs);
	db.close();

dineshsprabu / MySQL_query_adding_auto_increment_field.txt

Created February 8, 2016 12:42

[MySQL] Adding Auto Increment Field to an Existing Table Using SELECT

	/* This can be used if the table doesn't have an existing Primary Key */

	SELECT @s:=@s+1 as id, <table-name>.* from <table-name>, (SELECT @s:= 0) as s;

dineshsprabu / return_promise_from_function.js

Created February 11, 2016 13:17

[NodeJS] Return a promise from your own function

	var mongo = require('mongodb');
	var monk = require('monk');
	var Promise = require('bluebird');

	/* DB connection */
	var dbName = ''
	var db = monk('localhost:27017/'+dbName);

	/* replace <collection-name> with your collection*/
	var collection = db.get(<collection-name>);

dineshsprabu / iptable_mongo_allow_localhost_only.sh

Created February 13, 2016 02:27

[IPTable] Make Mongo Accessible only by localhost

	iptables -A INPUT -p tcp -s localhost --dport 27017 -j ACCEPT
	iptables -A INPUT -p tcp --dport 27017 -j REJECT