Network Segmentation

Protect your business by dividing your network into isolated segments, each controlled by its own firewall rules. Contain breaches, segregate high-risk areas, and maximise the security of your private network.

What is network segmentation?

Network segmentation is the physical division of a network into separate parts. A network segment can contain just one machine or many machines. Each network segment can have its own hub or switch. In most cases a contiguous range of IP addresses will be assigned to each segment. Using a FireRack firewall, each segment can be protected from the other segments using its own set of firewall rules. Any data moving between segments must pass through the firewall.

Why is network segmentation necessary?

If an attacker successfully compromises a single machine in a network segment, every machine in that segment is at risk. A single compromised machine which shares a hub with other machines can packet-sniff data going to the other machines. This data could contain logins, passwords or other sensitive information.

Although the use of a switch instead of a hub can minimise the impact of packet sniffing, switch security can also be circumvented. A compromised machine connected to a typical switch is able to send broadcast packets to all other machines connected to that switch. When all is said and done, switches are primarily designed to improve network performance, not to act as a firewall on a LAN.

Typically the attacker will have compromised a machine in the DMZ (DeMilitarised Zone) segment. By segmenting your network, you can contain that security breach to just the DMZ. Any attacker who has compromised a machine in the DMZ has still got to traverse the firewall to attack any additional segments, such as the private segment. A well-configured firewall will not allow machines in the DMZ to connect to arbitrary machines or ports in the private segment.

Our main objectives

Our overriding objectives in segmenting the network are:

  • Maximise the security of the private network segment
  • Damage Limitation — minimise the potential scope of a security breach
  • Segregate high risk areas

In most organisations, we do not wish to offer up data such as staff pay, personal staff data, internal reports and detailed accounts on our publicly accessible web site. If your web site and your confidential data reside in the same network segment, this just might happen. For this reason we pay special attention to the "Private" segment of the network. It is the network segment which should have zero exposure to the Internet.

Common segmentation scenarios

The way administrators segment their networks will vary widely depending on the way their company operates and interacts with the Internet. Whatever model of business you operate, you must always plan for the worst possible case.

1. Typical Small Business

The main use this small business makes of the Internet is to access information on the World Wide Web. This company also hosts its web site on its own web server and runs its own mail server.

  • Private Segment — All workstations and servers containing data not for public access. The firewall allows inbound mail to the internal mail server only via a mail relay in the DMZ.
  • DMZ Segment — The web and mail-relay servers. The web server cannot connect to machines on the private network. All email goes via the mail relay, which is permitted to connect to the internal mail server on port 25 (SMTP) only.

2. Internet Service Provider / Web Hosting Company

In addition to the needs of a Small Business, a Web Hosting Company has servers accessible for authoring and email retrieval from arbitrary external IP addresses. Web servers may allow authors to install their own CGI scripts, and email is retrieved using plain-text passwords that could be intercepted.

  • Private segment — Internal operations
  • Public Web Servers — Customer web sites
  • Mail Servers — Customer email processing
  • DNS Server — Primary DNS, the most sensitive resource
  • Corporate Web Server — Company web site linked to sensitive databases

3. Colocation Hosting Company

The most hostile environment of all. Customers do not know or trust one another, and the colocation company does not administer the servers. Each customer is responsible for securing their own server. The solution is to place each colocated machine in its own network segment using a MultiPort firewall such as the FireRack MultiPort, supporting up to 4096 separate segments.

4. Educational Institution

Schools and Colleges have multiple networks supporting different classes of workstation. A FireRack firewall allows a single Internet connection to be safely shared across segments, with each segment protected by its own Virtual Firewall. Control of different segments can be delegated to different departments.

How a "Transparent" Firewall helps

The transparency feature of the FireRack Firewall allows you to segment your network without segmenting your address space. This saves IP addresses, as multiple gateway, broadcast and network addresses will no longer be necessary.

The firewall is transparent to other machines on the network. No computers need to be reconfigured to use the firewall, and no address-space segmentation is necessary.

Protect Your Network with FireRack

Contact us to discuss how network segmentation can improve the security of your infrastructure.