Google Compute Engine does not allow outbound connections on ports 25, 465 and 587. These SMTP ports are blocked by default due to abuse.
For sending emails through the Google cloud compute instance Google recommends the following:
Relay emails through your G suite(formerly known as Google Apps) account
Relay using third party email service such as Sendgrid, Mailgun or Mailjet.
Connect your instance to your network via VPN and use your network to send email
With setting up the relay service we would need to configure and install Postfix. We won’t be installing and configuring Postfix on this tutorial. Instead we would be utilizing a WordPress WP Mail Plugin that would allow us to use a Gmail SMTP to send emails. I recommend setting up a new gmail account just for this purpose.
I’ve been doing a small bit of Google Cloud Compute(GCP) configurations to run this blog. I thought I’ll start sharing some of the steps I’ve gone through which could be useful to others out there. So I’ve setup a GCP instance and configured it with a WordPress Bitnami stack. I’ve got some videos of those in this playlist if you want to follow along.
But on this post I would be discussing about accessing phpMyAdmin on GCP via an SSH Tunnel on your Mac.
In order to access phpMyadmin on a WordPress Bitnami stack from Google Cloud Compute you need to do this using an SSH tunnel. On the WordPress Bitnami stack, phpMyAdmin is blocked from the public and only accessible from the localhost. This is where SSH tunnel comes in. Basically you access the localhost on a particular port on your computer that forwards that information to the remote server on an encrypted channel and then the remote server sends the content back to the local computer.
Here is an illustration on how that access is provided via the SSH tunnel.
Another example of using SSH tunnel is when a website is blocked from your company firewall or proxy filter, you can use SSH tunnel to bypass the proxy and connect to a remote computer that has no restriction and can access the blocked website.
With that said, lets connect via SSH tunnel on your Mac.
Open the terminal and change directory to where your private key is located
Type in following, replace the private key name, user and IP to match yours. Enter passphrase when prompted.