SSL Handshake Explained

The setting up of a Secure SSL/TLS connection is known as the SSL handshake process. This will be performed for all the websites starts with https://.
The SSL handshake process can be explained in 6 different steps.

1.    Client Web Request - Client Hello
2.    Server Responds - Server Hello.
3.    Client validates the Certificate
4.    Client generate and encrypt the session key
5.    Server decrypts the session key
6.    Encrypted data exchange takes place.

1. Client Web Request - Client Hello
This is the initiation of the SSL/TLS communication. Client Sends a "Hello" message to the Server.
Basically, this Hello means, Hello, i want to set up a secure connection with you but before that let me introduce myself. I supports this version of SSL/TLS , These are the cipher Suit/protocols i support and these are the data compression methods i support.

2. Server Responds - Server Hello.
Then the Server respond to the Client with a Server Hello. So the Server telling to the Client that, Hello, i can also understand different cipher protocols, but i will select one Cipher suite that we both can understand. Also selecting a common data compression method.
Additionally, i am sharing my certificate/public key with you.

3. Client validates the Certificate
The Client validates the certificate with its CA and proceeds to the next step.

4. Client generate and encrypt the session key
By using the data learned, the client generates a secret key knows as a "Session Key" and encrypts it with the Server's Public key.
The Encrypted message (key) is then send to the Server. Only the server can decrypt the message to get the Session key.

5. Server decrypts the session key
The Server ,by using its Private key decrypts the message and gets the session key.
Server also informs the client that ,for all the future communication between us for this particular session ,we will be using this session key and the SSL handshake is completed.

6. Encrypted data exchange takes place.
The SSL handshake is now complete and the session begins.
The client and the server will now use the session key to encrypt and decrypt the data they send to each other and to validate its integrity.

Download Microsoft Office 2019 offline installer.

When you do malware analysis of documents or office files, it is important to have Microsoft Office installed in your Lab machine. I am using flare VM and it doesn't comes with MS Office. Since Microsoft is promoting Microsoft 365 over the offline version, finding the offline installer is not that easy. Here is the list of genuine Microsoft links to download the office .img files. Download Microsoft Office 2019 Professional Plus : https://officecdn.microsoft.com/db/492350F6-3A01-4F97-B9C0-C7C6DDF67D60/media/en-US/ProPlus2019Retail.img Download Microsoft Office 2019 Professional : https://officecdn.microsoft.com/db/492350F6-3A01-4F97-B9C0-C7C6DDF67D60/media/en-US/Professional2019Retail.img Download Microsoft Office 2019 Home and Business : https://officecdn.microsoft.com/db/492350F6-3A01-4F97-B9C0-C7C6DDF67D60/media/en-US/HomeBusiness2019Retail.img Download Microsoft Office 2019 Home and Student : https://officecdn.microsoft.com/db/492350F6-3A01-4F97-B9C0-C7C6DDF67D60/media/en-U...

RUST error: linker `link.exe` not found

While compiling Rust program in a windows environment, you may encounter the error : linker `link.exe` not found. This is because of the absence of the C++ build tools in your machine. For compiling Rust programs successfully, one of the prerequisites is the installation of the Build Tools for Visual Studio 2019. Download the Visual Studio 2019 Build tools from the Microsoft website. After the download, while installing the Build tools, make sure that you install the required components (highlighted in Yellow) This will download around 1.2GB of required files. Once everything is successfully installed, reboot and re-run your rust program and it will compile successfully. Read More on RUST Hello World Rust Program : Code explained RUST Cargo Package Manager Explained Data Representation in Rust.

Cisco ASA: Disable SSLv3 and configure TLSv1.2.

For configuring TLS v1.2, the ASA should run software version 9.3(2) or later. In earlier versions of ASA, TLS 1.2 is not supported.If you are running the old version, it's time to upgrade. But before that i will show you the config prior to the change. I am running ASA version 9.6.1 Now ,set the server-version to tlsv1.2, though ASA supports version tlsv1.1, its always better to configure the connection to more secure. Server here in the sense, the ASA will be act as the server and the client will connect to the ASA. #ssl server-version tlsv1.2 set the client-version to tlsv1.2, if required. #ssl client-version tlsv1.2 ssl cipher command in ASA offers 5 predefined security levels and an additional custom level. #ssl cipher tlsv1.2 high we can see the setting of each cipher levels using #show ssl cipher command. Now set the DH group to 24, which is the strongest offered as of now in the AS...

How to Install Netmiko on Windows?

Netmiko, developed by kirk Byers is an open source python library based on Paramiko which simplifies SSH management to network devices and is primarily used for network automation tasks. Installing Netmiko in linux is a matter o f one single command but if you need to use Netmiko in your Windows PC, follow this process. 1) Install the latest version of Python. 2) Install Anaconda, which is an opensource distribution platform that you can install in Windows and other OS's (https://www.anaconda.com/download/) 3) From the Anaconda Shell, run “ conda install paramiko ”. 4) From the Anaconda Shell, run “ pip install scp ”. 5) Now Install the Git for Windows. (https://www.git-scm.com/downloads) . Git is required for downloading and cloning all the Netmiko library files from Github. 6) From Git Bash window, Clone Netmiko using the following command git clone https://github.com/ktbyers/netmiko&#8221 7) Onc...

Recovery Procedure: Alcatel-Lucent Omni-Switch not booting AOS: Going to Mini-boot prompt.

Problem: Switch not booting AOS; Going to Mini-boot prompt. Model: Alcatel-Lucent OS6850 [Note:The same procedure might be applicable for different models of Omni-Switches, However, for this illustration, i have used OS-6850 ] Reason: This problem may occurs due to corrupt AOS image files or misconfigured boot parameters. Hence switch cannot boot the images properly and will go to Mini-boot prompt. Work Around: [Note: This zmodem procedure consumes a lot to time to finish the process.] 1.) Power off your OS6850 2.) When you switched it back on, stop it before the Miniboot (there is some counter counting down from 4). Press Enter to break. 3.) You will have the following prompt " => " 4.) Enter " setenv baudrate 115200 ”. Increasing baudrate helps to increase the data transfer speed using zmodem. 5.) Enter " saveenv " 6.) Enter " boot " 7.) The switch should run now in baud rate 115200 (so you have to change your clients ter...

[FIX] yt_dlp.utils.DownloadError: ERROR: You have requested merging of multiple formats but ffmpeg is not installed

[ISSUE] While running your python code or while executing a job : yt_dlp.utils.DownloadError: ERROR: You have requested merging of multiple formats but ffmpeg is not installed [CAUSE] Your code is unable to find ffmpeg installed in your system. [FIX] Install ffmpeg in your system. 1) Download ffmpeg package from Git or already compiled executable from the official website . 2) Once downloaded, extract the zip file and place it in your desired location. eg: C:\ 3) Now add the ffmpeg bin directory location in the user environment variable path. In the User variables section. Select Path and click on New. Click on New and add the path. Now compile your code and it should work. For the python code to download YouTube playlist, visit https://github.com/jaacostan/YTDL

[FIX] Can't locate Net/SNMP.pm in @INC (you may need to install the Net::SNMP module)

I was trying to use the snmpenum.pl in my lab and encountered this error. Can't locate Net/SNMP.pm in @INC (you may need to install the Net::SNMP module) I searched over the internet for the fix , but couldn't able to find something direct. However, going through some of the stackoverflow pages, i fixed it and is explained below. 1) First install the required packages related to snmp utilities. sudo apt-get install libsnmp-perl 2) Install the SNMP module for perl. perl -MCPAN -e 'install Net::SNMP' That's it. And i was able to run the script.