Why Are Firewalls So Important to a Cloud Migration?

What is the essence of a cloud migration? What major function does cloud migration provide?
Simply stated, the general purpose of a cloud migration is to move resources in the datacenter to a cloud provider (such as Microsoft Azure cloud). These resources can include, but are not limited to:

• general-purpose servers
• routers
• switches
• circuits
• databases/data warehouses
• applications
• file shares/file servers
• client computers (using technologies such as Azure VDI or Windows 365)
• email and productivity software access (using technologies such as M365 [formerly Office 365])

And so much more.

Recently, I discussed two primary reasons companies are moving to the cloud. Please view my previous post on why companies migrate to Azure if you would like that information about the process.
Now, let’s look at the total migration objectively.

We are taking both data and data processing structures from our SECURE data centers that have gained our trust over the last years (even decades, at some Enterprises), and we are moving them to a new location. Even if this location was a vault in the FBI, there would be an element of concern about the overall effectiveness of the new location’s security process.

This security concern is one of the most important challenges to overcome with any Azure cloud migration. Specifically, the client or company’s concern that even with a super-secure company like Microsoft, the design of the new environment — or more specifically, the process used to migrate and position the resources — will not be as secure as what is already in the current ‘legacy’ datacenter.
This is where the firewall comes into play.

The firewall is key and very important to the migration process to help reduce concerns like this, both logically and practically. In short, firewalls are resources that function as guards at the gate; they either allow data to pass along or reject it.

Typically, a Network Engineer will program a process/algorithm that will instruct the firewall what data to accept. The standard practice in Network Engineering is to list everything that will be accepted. The last step is to essentially ‘deny anything that does not fit what I have already allowed.’ In Network Engineering lingo, this is called the ‘deny all’ statement.

The usual configurations for a firewall include a name or label for each rule, the source IP address, the destination IP address, the ports that should be allowed, and the protocols that should be allowed. I have added an example below this statement:

Name: NEW_RDP_PORTS_CR19521958
Protocol: TCP
Source Addresses:
Destination IP Adresses:
Destination Ports: 81052

Do you notice the part of the name that’s written as “CR19521958” in the above example? It is added to define the Change Management request that approved placing this new rule into the infrastructure.

Now that we have all of that out of the way, let’s quickly answer the question at hand:

Why are firewalls so important to a cloud migration?

The simple answer is that they are a key line of defense against data hacks — infrastructure security.

Basically, a firewall (or many of them) is the first device that all data is filtered through as soon as it is out of the WAN cloud (think internet traffic; coming and going). This super-specific filtering process adds major security to any environment — and that makes your Cyber Security team VERY HAPPY!