[Windows 7] Your connection is not private NET::ERR_CERT_AUTHORITY_INVALID for all HTTPS sites

Recently, Windows 7 users reported an error that they could not access the websites "Your connection is not private", "NET::ERR_CERT_AUTHORITY_INVALID". This error is encountered in all browsers on the machine. And it is encountered only when accessing websites with https. In other cases, the website displays a blank page because the static content files cannot be loaded. This error is encountered because the customer's Windows 7 operating system is not fully updated with security patches.

SSL certificate error on all browsers, for all HTTPS sites

Solved

To fix this, If you are using windows 7, please install security update KB3004394 from Microsoft.

You can download the KB3004394 package from the official Microsoft website using the following link:

KB3004394 Update for Windows 7 X86 (32 Bit)

KB3004394 Update for Windows 7 X64 (64 Bit)

To install the update successfully, Windows must have the Windows Update feature enabled.

After installing the update above, please clear your browser's browsing history data and restart your computer. HTTPS sites can now be accessed normally.

In addition, you should also install all the latest updates for your windows 7 operating system through the Windows Update feature. This will help keep your computer safe and less prone to problems.

Done !

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[Tips] How to use Cloudflare Free SSL for Socket.io Server

Free SSL is a very interesting feature of Cloudflare. Cloudflare SSL has full support for WebSocket protocol. However, if you are using the web in conjunction with a socket.io server on the same server, you may encounter problems with the ssl port. Because the default port for ssl is always 443 but it is already used by the web server.

There are many ways to handle this problem, here I will guide you in a very simple way. That's how to configure Socket.io SSL through a proxy using Apache or Nginx.

Prepare:

NodeJs SocketIO server is listen on port 8088

Webserver (Apache or Nginx) is listen on port 80 and 443

Step 1: SocketServer config

Configure NodeJs SocketIO server to run in long polling mode without ssl on a certain port, eg port 8088.

Eg:

var app = require('express')(); //npm install express
var http = require('http').createServer(app);
var socketServer = require('socket.io')(http, { //npm install socketio
cors: {
origin: "*",
methods: ["GET", "POST"]
},
  transports: ['polling']
});
http.listen(8088, () => {
console.log('listening on port 8088');
});

Configure socket.io client to use 'polling' mode

Eg:

var socket = io('https://subdomain.yourdomain.com', { });
socket.on('connect', function () {
console.log('connected');
});

Step 2: Configure virtualhost proxy for Socket Server

Configure virtual host proxy to forward port 80 from cloudflare to the actual port of our Socket Server (I listen on port 80 because I am using Cloudflare flexible ssl, if you use Cloudflare full ssl or full strict ssl then listen on port 443 like your other virtualhost)

Apache:

<VirtualHost *:80>
    ServerAdmin admin@yourdomain.com
    ProxyPreserveHost On
    ServerName subdomain.yourdomain.com
    ProxyPass / http://127.0.0.1:8088/
    ProxyPassReverse / http://127.0.0.1:8088/
</VirtualHost>

Nginx:

server {
    listen 80;
    server_name subdomain.yourdomain.com;
    location / {
        proxy_set_header   X-Forwarded-For $remote_addr;
        proxy_set_header   Host $http_host;
        proxy_pass         http://127.0.0.1:8088;
    }
}

Done !

Remember to reload your web server 

Now your NodeJs Socket Server is working perfectly with free ssl from CLoudflare

 

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Git: How to fix Error Pulling is not possible because you have unmerged files

If you try to pull new code while some local files have been changed without commit, you will get this error.

Error Pulling is not possible because you have unmerged files.

or

Error: Your local changes to the following files would be overwritten by merge

To fix it you have 2 options:

* Method 1: Commit the changes, then pull the new code

- Add new files if available

git add filename1.xyz folder/filename2.xyz  

or (add all new file)

git add -A    

- Commit new changes

git commit -m "Add new file or something need to noted"

* Method 2: Remove all local changes to update new code

(We often encounter this situation on the server)

To do so, run the following command:

git reset --hard origin/master

- note: 'master' is the name of the branch you want to update new code from that.

Done ! Now we can update new code by git pull command.

git pull

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MySQL: Allowed to remote connect to MySQL server

MySQL Error : Host 'xxx.xx.xxx.xxx' is not allowed to connect to this MySQL server

How to fix it ?

STEP 1: Change mysql config :

vi /etc/mysql/my.cnf

Comment out following lines or edit to your client ip :

#bind-address           = 127.0.0.1
#skip-networking

Restart mysql server:

service mysql restart

STEP 2: Change GRANT privilege :

Login MySQL using command line .
Then run a command like below to grant access for user. Replace 'username' and 'password' with your username and password.

CREATE USER 'username'@'%' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON *.* TO 'username'@'%' WITH GRANT OPTION;

* '%' mean you can remote access from any ip address, You can replace it with a specified ip address.

Then flush MySQL :

FLUSH PRIVILEGES;

If it's still not working. Let's check your server firewall (iptables ...) and client firewall (windows firewall, antivirus software)

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PHP: Create big unique ID like Facebook or MongoDB

Most of web application using a relational database management system (MSQL, SQL ..etc) to store data as records. We need an unique id to use as a key Primary.
How to do it ?
* SQL AUTO INCREMENT a Field :
--> 1,2,3,4,5..... #anyone can count the number of your records and more

* PHP uniqid :
--> 541cf7f7d685e, 541cf7f7d685e, 541cf7f7d685e .....  #somewhat similar?

* Or use a custom function like this :

function gen_id() {
    return sprintf( '%04x%04x%04x%04x%04x%04x%04x%04x',
        // 32 bits for "time_low"
        mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ),

        // 16 bits for "time_mid"
        mt_rand( 0, 0xffff ),

        // 16 bits for "time_hi_and_version",
        // four most significant bits holds version number 4
        mt_rand( 0, 0x0fff ) | 0x4000,

        // 16 bits, 8 bits for "clk_seq_hi_res",
        // 8 bits for "clk_seq_low",
        // two most significant bits holds zero and one for variant DCE1.1
        mt_rand( 0, 0x3fff ) | 0x8000,

        // 48 bits for "node"
        mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff )
    );
}

Result : 6800cd499f25434aac48c0bb51f46307, caa02c4831194690ad8458c3a4e07a0c, 7488a4c459d64f8dbacd2b79f44ed4bf ......

- differences
- professional (like facebook, google, MongoDB ...)
- high performance
- unrestricted

Reference : PHP uuid lib

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Excel: How to remove VBA password from excel file

If you want to remove VBA password protect excel file without password, please follow the following guidelines.

Step by step :

1. Download a HEX editor (HxD Hex Editor)
2. Open xls/xlsx file and Save As xls. Do this even if the file is xls, just to be sure
3. Open xls file with a hex editor
4. Search for DPB
5. Replace DPB to DPx (Note: the editor overrides, not inserts. So pay attention)
6. Save file
7. Open file in Excel
8. Click "Yes" if you get any message box. There will be a few
9. Click Alt + F11
10. Click Tools -> [Project Name] Properties
11. Click Protection
12. Enter a new password twice
13. Save
14. Close and open the file again
15. Type your new password to get to the required information.

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Linux-vsftpd : restrict user to root directory

To avoid security issues or restrict user to root directory you have to limit users of vsftp to only their home directory. So how to do it ? 

Open vsftpd configuration file - /etc/vsftpd/vsftpd.conf :

Make sure following line exists and uncommented (add if not exists):

chroot_local_user=YES 

Save and close the file. Restart vsftpd service.

/etc/init.d/vsftpd restart 

 Done. Using a ftp client to check with some acccount.

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CSS: Position fixed not working in IE

* IE 6 does not support position: fixed
* Other versions of IE (7,8,9) don't support position: fixed in quirks mode when you missing Doctype.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

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QuickTip: Check number of facebook share url

The easiest way to see number of people that share an url :

http://graph.facebook.com/http://zero-exception.blogspot.com

Result :

{
   "id": "http://zero-exception.blogspot.com",
   "shares": 528,
   "comments": 39
}

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