Remote connection on GCP VM instances

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In this tutorial, we will configure a Linux Virtual Machine that is hosted on Google Cloud Platform (GCP) to accept remote connection through SSH using a public/private key. If you do not have a GCP Learn here how to create a Google Cloud Platform Account. For Windows users I recommend two steps before start:

Install the ConEmu. It is a Windows terminal with a lot of enhancement.
Install Hosts File Editor. It is a Editor for the Windows Host File.

Starting the VM Instance and configuring the Hostname

Go to the Google Cloud Platform (GCP) dashboard and start the VM Instance. (See this tutorial on how to create a VM Instance).
Copy the External IP and check if you can reach the remote machine with a ping command. Warning: This IP address can change when restarting the VM instance.

>ping 34.82.27.184

Open the software Host File Editor and configure the Hostname for this IP address. It this example I gave the name becloudnativedev. When the external UP address changes after a restart, update the host file with the new value. The software will edit the Windows host file, it is very similar to the Linux /etc/hosts file.
Perform a ping command to check whether you can reach re remote machine with the host name chosen.

> ping becloudnativedev

Pinging becloudnativedev [34.82.27.184] with 32 bytes of data:
Reply from 34.82.27.184: bytes=32 time=188ms TTL=52
Reply from 34.82.27.184: bytes=32 time=186ms TTL=52
Reply from 34.82.27.184: bytes=32 time=185ms TTL=52
Reply from 34.82.27.184: bytes=32 time=189ms TTL=52

Ping statistics for 34.82.27.184:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 185ms, Maximum = 189ms, Average = 187ms

Generating the Public/Private key to remove connection

Generate the public and private key files with the command ssh-keygen.

ssh-keygen -t rsa -b 4096 -f %USERPROFILE%/.ssh/becloudnativedev.key

When asked for the passphrase, keep blank and just type enter to confirm. The output will be similar to the following.

Generating public/private rsa key pair.
Created directory 'C:\Users\eduardo/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in C:\Users\eduardo/.ssh/becloudnativedev.key.
Your public key has been saved in C:\Users\eduardo/.ssh/becloudnativedev.key.pub.
The key fingerprint is:
SHA256:TsRNK0F7ybvCOC0mnzSpkBWDyiuvMVfu8i5mk5Yhs6E eduardo@notebook
The key's randomart image is:
+---[RSA 4096]----+
|       .o .      |
|   .   . * o     |
|  . o   = *      |
|..   o . o .     |
|..  o   S .      |
|+ o=   B   .     |
|=*++o O = .      |
|E=Xo * = .       |
|.=.*= o          |
+----[SHA256]-----+

Go to the %USERPROFILE%/.ssh folder and check the created files becloudnativedev.key and becloudnativedev.key.pub

C:\Users\eduardo\.ssh
λ ls -la
total 45
drwxr-xr-x 1 eduardo 197121    0 Sep 19 00:01 ./
drwxr-xr-x 1 eduardo 197121    0 Sep 18 23:46 ../
-rw-r--r-- 1 eduardo 197121 3243 Sep 19 21:32 becloudnativedev.key
-rw-r--r-- 1 eduardo 197121  743 Sep 19 21:32 becloudnativedev.key.pub
-rw-r--r-- 1 eduardo 197121  175 Sep 19 00:01 known_hosts

Generating a Public/Private Key using using PuttyGen

With the following steps, you can generate the keys using the software PuttyGen. You do not need to follow these steps if you followed the previous one.

Donwload and open PuttyGen
Click on Generate button and keep moving the mouse while the progress bar fill out.
Click on Conversions -> Export OpenSSH key and save this private key into a file named becloudnativedev.key.
Copy the text of the public key from the PuttyGen and save into a file becloudnativedev.key.pub .
When try to test the SSH command, If you get a Permission denied error due a Bad permission you will need restrict the permission of the becloudnativedev.key file . Check this thread on stackoverflow.

Generating a Public/Private Key on Linux

If you are on Linux you can generate the keys with the following steps. You do not need to follow these steps if you followed the previous one.

Go to .ssh folder cd ~/.ssh
Generate a public and private key ssh-keygen -t rsa -f ~/.ssh/becloudnativedev.key.
Two files will be created at ~/.ssh. becloudnativedev.key and becloudnativedev.key.pub
Change the permissions of the private key chmod 600 becloudnativedev.key

Configuration the VM Instance to accept remote connections

Lets configure the VM instance to allow SSH connections using our keys.

Go to VM Instances on GCP and click on the instance you created
Click on Edit button and scroll down to SSH Key section.
In the session Click on Show and edit and paste into the text box the content of the file becloudnativedev.key.pub
Scroll down and click on Save button.

Testing the remote connection

Now it´s time to confirm that everything works and connect on our remote machine.

Open the console go to the %USERPROFILE%/.ssh directory and connect remotely to the VM Instance using the command ssh -i becloudnativedev.key eduardo@becloudnativedev

  λ ssh -i becloudnativedev.key eduardo@becloudnative
  key_load_public: invalid format
  The authenticity of host 'becloudnative (35.199.170.231)' can't be established.
  ED25519 key fingerprint is SHA256:Zlbz3z6tObcWd3UQyCf+1giF4aJeZ11StwY4vMrPMmQ.
  Are you sure you want to continue connecting (yes/no)? yes
  Warning: Permanently added 'becloudnative' (ED25519) to the list of known hosts.
  educostabra@cloud-native ~ $

It´s done! The remote machine accepted the SSH connection and used the private key to authenticate without the need to ask you password. Keep you private key safe and do not forget of shutdown your VM Instance in case you will not use.

Watch the following video and see the previous steps being executed on practice: