How to setup SSH Pentest Lab

Probing through every open port is practically the first step hackers take in order to prepare their attack. And in order to work one is required keep their port open but at the same time they are threatened by the fear of hackers. Therefore, one must learn to secure their ports even if they are open.

In this article we will secure SSH port so that even if it’s open no one will be able to exploit it. First of all let’s install SSH server using following command:

sudo apt-get install openssh-server

Once the server is installed start SSH service by typing :

service ssh start

To confirm the working of SSH, use the following command :

service ssh status

As the service of SSH is started, scan it in your kali’s terminal using nmap:

nmap -sV 192.168.1.17

Scanning will show that on port 22 is open with the service of SSH. Configure this port using PUTTY. For configuration in putty, give the IP address in host name along with port number and then select SSH and then finally click on Open.

Upon connecting, it will ask for password, give the said password and press enter.

How to Secure SSH Connection

Now that SSH has been configured. We can use our first measure of security i.e. port forwarding. In computer>etc>ssh you will find a file with the name of “sshd_config”.

Open this file and wherever it says port 22, change it to port 2222.

This way we have forwarded SSH service from port 22 to port 2222. Let’s check it on nmap to confirm.

nmap -sV 192.168.1.17

SSH Connection using PGP Keys

This way we have applied our first measure of security. Now for our second measure of security download and install PUTTY Key Generator. Open it and click on Generate button on low right side.

This will generate a public and private key. Out of these save the private key.

The private key will be saved as shown in following image. You can rename it at convenience as I have named it ssh login key.

Now open terminal of your server and type:

ssh-keygen

The above command will create a folder named .ssh and then create an empty text file with the name authorized_keys in the said folder.

 Copy the “ssh login key.ppk” file which are created previously into the .ssh folder.

In the terminal, move into .ssh folder and type the following command:

puttygen –L “ssh login key.ppk”

This command will generate a key. Copy this key in the empty file which we created earlier with the authorized_keys.

Then in putty configuration tab, go to data and give Auto-login username

The open SSH>Auth and give the path of SSH login key (private key that was generated). 

And then in session tab give the IP address and port number which is now 2222 due to our first measure of security.

And then click on open. It will open without asking for password as you have configured the key.

But this doesn’t mean it can’t be open using password. And still we are vulnerable to hackers. Therefore we are going to apply third measure of security i.e. to disable password completely. For this, go to computer>etc>sshd_config.

Here, change password authentication from yes (as shown the image above) to no and uncomment (as shown in image below).

 

And now that we have successfully applied three measures of security our port is safe from anyone and everyone. To this port the hacker will require physical access to you hardware which is impossible. And if you want to access SSH from another machine then just configure the same key in that PC too and it have access to it.