Making a Local Dev Server accessible via Public Domain using Cloudflare Tunnel

Hi all,

Today, we are going to discuss how you can publicly access the local running server with a domain and Cloudflare tunnel.

Pre-requisites

1. Domain
2. DNS on Cloudflare
3. Cloudflare One account access
4. Local server

Set up the environment

Application

Make sure your application runs locally on a port like 8000,9000 etc.

Cloudflare Tunnel

1. Log in to your Cloudflare One account.
2. Go to "Zero Trust".
3. Expand Networks and select Connectors.
4. Click on “Create a tunnel”.
5. Select “Cloudflared”.
6. Give a name to your tunnel.
7. Click on “Save”.
8. In the "Choose your environment" section, select the environment where the server is running.
9. Follow the instructions to install and run a connector.
10. Here, you need to move to your server machine.
11. Open the terminal and perform the instructions to install the "cloudflared" tool.
12. Run using the token (part of the command).
13. Once the installation is completed. Click on Save.

Add IP/CIDR

1. Edit the tunnel to add the IP/CIDR.
2. Choose based on your local DHCP.

Published application routes

1. Click on “Add a published application route”.
2. Give an optional subdomain.
3. Select the domain from the dropdown.
1. You need to have your domain managed by Cloudflare (DNS).
4. An optional path to make sure you have a frontend and a backend that work together.
5. Under service, select Type as HTTP, and your local machine server port.
6. Select the URL of the server application, including the localport.
1. localhost:9000
7. Click on “Save”.

Note: If you have a frontend and a backend, then you need to add one more application route.

In my scenario, the frontend path is * with localhost:9001, and the backend path is api/* with localhost:8000.

Run the tunnel

1. Make sure your local web server is running
2. Log in to cloudflared

• cloudflared tunnel login

• Authorize the tunnel on the web browser post login
3. List the tunnels

• cloudflared tunnel list

4. Get the tunnel token from the tunnel you created in Cloudflare connectors
5. Run the command on the local terminal

• cloudflared tunnel run --token eyJhIjoiM2...

6. Now, you should be able to browse your configured subdomain with your local web server content. 

Troubleshooted issue

If the frontend with path "/*" is above the backend route, then your backend APIs will never be reached.

So, "move up" the backend with "/api/*" path above the frontend to serve the requests.

Feel free to reach out to me if you have any doubts and clarifications needed at my email psrdotcom@gmail.com

Generate Free SSL HTTPS Certificates with 90 days validity using letsencrypt

 Hi all,

As discussed in my earlier blog, Generate Free SSL Certificate using ZeroSSL where the limitation of one free certificate on ZeroSSL can be eliminated using Get HTTPS for free!

This process includes the following prerequisites and procedures.

Note: This process is not for beginners or production usage scenarios. Use this process if you are knowledgeable about certificate generation.

Prerequisites

• OpenSSL command line
• [Li]nix / Mac OS

Procedure

• Open the URL https://gethttpsforfree.com
• It has 5 steps
• Account Info
• Certificate Signing Request
• Sign API Requests
• Verify Ownership
• Install Certificate
• In each step, some commands or processes need to be followed to get the free SSL certificate.

1. Account Info
1. In this step, we will be providing the email and public key.
2. Keep the generated private key security in your system.

• Note: If you are unsure about the public key generation commands, click on the "how do I generate this?" link, which is available over the public key input textbox.

2. Certificate Signing Request (CSR)
1. Generate the CSR for the required domains

• Note: You can generate the CSR for wildcard certificates and www subdomain with the same command

2. Try to follow the same format, including the line feeds mentioned below.

#change "/etc/ssl/openssl.cnf" as needed:
    #  Debian: /etc/ssl/openssl.cnf
    #  RHEL and CentOS: /etc/pki/tls/openssl.cnf
    #  Mac OSX: /System/Library/OpenSSL/openssl.cnf

    openssl req -new -sha256 -key domain.key -subj "/" \
      -reqexts SAN -config <(cat /etc/ssl/openssl.cnf \
      <(printf "\n[SAN]\nsubjectAltName=DNS:foo.com,DNS:www.foo.com")) 

3.  Sign API Requests
1. Sign all the requests with the private key

• Note: You need to copy the command and execute it on your PC/Mac terminal, and the result needs to be pasted on the web page.

4. Verify Ownership
1. In this step, you need to prove your domain ownership
2. You will be given 3 options
1. Python server
2. file-based
3. DNS record (I've used this option)
1. Update the DNS records with new TXT entries, and use the online dig tool to make sure the records are visible.
2. After we verify the availability of the records, you need to click on the respective buttons on the web page.
3. Repeat the same steps for each domain on CSR (www and any sub-domains).
5. Install Certificate
1. You will be able to receive your certificate in "chained.pem" format
2. Copy and paste the first certificate section (e.g. the first "-----BEGIN CERTIFICATE-----" section) into a text file named "domain.crt".
3. Copy and paste the second certificate section (e.g. the second "-----BEGIN CERTIFICATE-----" section) into a text file named "intermediate.pem".

• Note: Expand the "how do I install this?" link for quick help.

Hope this will help you to generate free SSL for your websites.

Request you to send your valuable feedback and comments to psrdotcom@gmail.com

Calculate the private key of RSA algorithm

 Hi folks,

Today we are going to see how we can calculate the private key of RSA.

Inputs

Random prime numbers p and q

Public key (n, e)

Procedure

1. Compute n (Random modulus)

n = p * q

2. Compute e (Derived Number)

e = (p - 1) * (q - 1)

3. Form the public key

GCD(pubkey, e) should be 1

pubkey = 1 mod e

4. Private key

prikey = (1 + k * e) / pubkey

0 < k < e - Iterate until we get a number without fraction

Real example

Inputs

p = 7, q = 17, pubkey = 11

1. n = 7 * 17 = 119

2. e = (7-1) * (17-1) = 96

3. pubkey = 11 

    GCD (11, 96) = 1

4. prikey computation

k=0, (1 + 0 * 96) / 11 = 0.09

k=1, (1 + 1 * 96) / 11 = 8.81

k=2, (1 + 2 * 96) / 11 = 17.5

k=3, (1 + 3 * 96) / 11 = 26.27

k=4, (1 + 4 * 96) / 11 = 35

prikey = 35

Hoping that this blog will be useful in understanding the RSA private key computation.

Send your valuable feedback and comments to psrdotcom@gmail.com

Generate or Create ECDSA - Elliptic Curve Digital Signature Algorithm Keys using OpenSSL in Windows

 Hi folks,

Today we will see how we can create ECDSA (Elliptic Curve Digital Signature Algorithm) Keys

Pre-requisites

OpenSSL

Add openssl bin directory to the environment PATH variable 

Generate Keys

Open Powershell and execute the following commands

1. Get the ECC curves list

openssl ecparam -list_curves

2. Generate a private key using your chosen curve

openssl ecparam -name prime256v1 -genkey -noout -out private-key.pem

3. Generate public key from the private key

openssl ec -in private-key.pem -pubout -out public-key.pem

4. Create a self-signed certificate with 1 year validity

openssl req -new -x509 -config "<opensslDirPath>/share/openssl.cnf" -key private-key.pem -out cert.pem -days 360

5. Convert pem to pfx

get-content private-key.pem, cert.pem | out-file cert-with-private-key

openssl pkcs12 -export -inkey private-key.pem -in cert-with-private-key -out cert.pfx

 Note: Enter the password when prompted (Optional)

Now, you can install the PFX file and check the certificate properties and make use of it.

Send your valuable feedback and comments to psrdotcom@gmail.com

Truecrypt Mount and Unmount in Windows

Hi friends,

I would like to share the information of mounting and unmounting truecrypt in windows

Please find the batch file here

https://gist.github.com/psrdotcom/8350f1469a7a396a886e86b3f29ef38a#file-truecryptmountunmount-bat

With the above batch file, you should be able to do following functionalities

1. Mount a folder as drive
2. Unmount the drive

Hope, this information is useful to you.

Please send your comments and feedback to psrdotcom@gmail.com

Andhra Pradesh Public Service Commision (APPSC) Government Jobs Apllication Challan and Submit Application Online for various posts using APOnline Services

Dear friends,

Very useful information for those who wants to apply various posts in the Andhra Pradesh Public Service Commision (APPSC).

Procedure:

1. Visit the APPSC website http://apspsc.gov.in/
2. Browse the "Online Application Submission" section
3. For any post, you need to fill the challan by clicking "Get Challan"
4. Upon successfully filling the challan form, you will get the challan in PDF format.
5. According to instructions, either you need to visit near SBI branch or APOnline center.
6. But, you can pay the challan online using APOnline services.
7. Just click on the link http://aponline.gov.in/apportal/index.asp
8. Click on the "Citizen Login" on left side of the page
9. Register/Sign in with your details.
10. Click on "Adhoc Services"
11. In the section of "Challan payments", choose "APPSC Challan Payment"
12. Enter your challan number
13. Your details gets appeared; Your name and other details.
14. Click on "Submit"
15. Now it will ask you to pay using any one of the bankers (SBI, HDFC, AXIS, IndianBank)
16. After the payment, you will get the transaction acknowledgement along with your "Journal" number.
17. Make a note of "Journal Number"
18. The next day after 2:00 PM, visit APPSC website http://apspsc.gov.in/
19. Click on the "Submit Application"
20. Before you submitting the application, you need to have your scanned photograph and scanned signature.
21. The dimensions of the photograph should be 3.5cm(Width) x 4.5cm(Height) [Around 276px * 354px]
22. The dimensions of the signature should be 3.5cm(Width) x 1.5cm(Height) [Around 276px * 118px]
23. Using any of the photo editors you can combine both the photograph and signature into one .jpeg image with the dimensions 3.5cm(Width) x 6cm(Height) [276cm * 472px]
24. The image size must be less than 50KB
25. Upload the image by clicking on browse option
26. Click on "Preview" button
27. Verify the photograph and signature in the page
28. Click on "Submit" button
29. You can download the submitted application form

All the very best for you exam.

For any queries, mail to psrdotcom@gmail.com