Each zone on a network is separated based on organizational role or level of security.
For example:
Secure Zone - These are the most sensitive systems, with mission-critical data.
General Work Zone - These are standard workstations and servers, with typical business data and functionality.
Low Security Zone - These are computers, network segments, and systems that have no highly sensitive information, and the breach of these systems would have minimal impact.
Types:
DMZ - Demilitarized Zones
A network segment located between the protected (internal) and unprotected (public) networks.
Provides a buffer zone / defense-in-depth.
Usually set up using firewalls.
Contains hardened systems that need to reach each network segment.
email
web
DNS servers
Extranet
A private network that uses Internet tech and the public telecom system to securely share part of a business's info or operations with suppliers, vendors, partners, customers, or other businesses.
Intranet
Websites or apps that are only accessible within the org's network.
Wireless Segmentation
Separating wireless access on an internal network.
Creating a buffer between wireless and wired networks.
Separating guest wireless access from internal networks.
Controlled by 801.1x - Port based access control.
MAC filtering - restricting access based on the device's NIC address (MAC).
Guest
Security Device Placement
Where should security devices be on a corporate network?
Firewalls / UTM (border)
IDS / IPS (border or internal segments)
VPN
Proxies (external)
Load Balancers
SIEM - log collection / correlation
Correlation Engine - A software application that programmatically understands relationships.
Used in systems management tools to aggregate, normalize, and analyze event log data using predictive analytics and fuzzy logic to alert the systems admin when there is a problem.
Applications that examine relationships between entries in firewall logs to understand possible attacks.
The forwarding and routing function should be disabled on the firewall to ensure the network segregation.
Segregation, Segmentation, & Isolation
Dividing a network into zones based on business or security needs.
Example: Accounting on a different network segment from manufacturing.
Logical (VLAN)
A network of computers that behave as if they are connected to the same wire even though they may actually be physically located on different segments of a LAN.
Virtualization
Virtualized servers and workstations - easier to separate.
You should not allow internet browsing on a virtualization host.
This can present possible security breaches through the introduction of spyware or malware.
Air Gaps
Physical separation.
VPN / Tunneling
A private network connection through an unsecured, public network.
Use to connect LANs
Remote devices appear as if they are local.
Methods:
Site-to-Site - Connect LANs across the internet.
Remote Access - Connect users or devices to a corporate network.
Remote Access Server (RAS)
SDN - Software Defined Network
The entire network is virtualized.
Allows for easier network segmentation.
Allows admins to place virtualized security devices anywhere.
The SDN architecture is:
Directly Programmable
Agile
Centrally Managed
Programmatically Configured
Open Standards-Based and Vender-Neutral
Honeypots / Honeynets
Use:
Systems or networks exposed to capture malicious activity.