Secure Enterprise Network Architecture

🔌 Secure Network Designs

Designing a secure network architecture begins with understanding the roles and functions of core devices:

Switches: Operate at OSI Layer 2, forwarding traffic based on MAC addresses. Use features like port security and VLANs for added control.
Routers: Work at Layer 3, directing packets across networks using IP addresses. Configure ACLs to control traffic flow.
Load Balancers: Distribute incoming traffic across multiple servers to improve performance and availability. Learn more about load balancing.
WAPs (Wireless Access Points): Extend network connectivity wirelessly. Use WPA3 and disable WPS for secure deployment.

Design with redundancy, separation of services, and secure administrative access in mind. Use layered defenses and avoid single points of failure.

Segmenting a network limits the spread of threats and isolates sensitive systems. Techniques include:

DMZ (Demilitarized Zone): Hosts public-facing services like web and email servers. Provides a buffer zone between internal and external networks. Learn more about DMZs on Wikipedia.
VLANs: Logically separate broadcast domains within switches. Used to isolate traffic by department, sensitivity, or access needs. Learn more about VLANs on Wikipedia.
Zoning: Group systems by security level or function and enforce access between them with firewalls or ACLs.

Monitor both north-south (in/out of network) and east-west (internal lateral) traffic for full visibility.

Placing devices correctly is critical to maintaining secure, efficient traffic flow:

Position IDS/IPS at network chokepoints to detect or block threats in real-time. Learn more about IDS and IPS.
Firewalls sit at network boundaries and between zones to enforce traffic policies. Learn more about firewalls on Wikipedia.
Place load balancers and proxies in the DMZ to offload web traffic and provide caching/filtering.
Use network access control (NAC) to restrict devices until they meet compliance. Learn more about NAC on Wikipedia.

Securing routing protocols prevents attackers from manipulating network paths:

Use OSPF with authentication to prevent rogue route advertisements.
RIP and BGP require protections against route poisoning and hijacking.
Enable DHCP snooping and Dynamic ARP Inspection (DAI) to stop spoofing and man-in-the-middle attacks.

Switches should use port security, disable unused ports, and implement VLANs with ACLs.

DNSSEC: Adds digital signatures to DNS queries to prevent spoofing. Learn more about DNSSEC on Wikipedia.
HTTPS: Encrypts HTTP traffic with TLS, used for secure web browsing. Learn more about HTTPS on Wikipedia.
SSH: Replaces insecure telnet for remote CLI access to devices. Learn more about SSH on Wikipedia.
FTPS/SFTP: Secure alternatives to FTP for encrypted file transfers.
LDAPS: Encrypts LDAP directory access to protect credentials.
IPsec: Offers encrypted tunnels (transport and tunnel mode) for site-to-site or remote access VPNs. Learn more about IPsec on Wikipedia.

Disable legacy and insecure protocols (e.g., Telnet, FTP, HTTP) wherever possible.

Reduce potential attack vectors by removing unnecessary services, patching regularly, and applying the principle of least privilege (PoLP):

Implement firewalls, IDS/IPS, antivirus, and endpoint detection & response (EDR).
Isolate critical assets via network zoning and segmentation.
Use defense-in-depth: layer protections across network, host, and application levels.
Conduct vulnerability scans and configuration audits regularly.

Remote access is essential but increases risk. Secure solutions include:

Full tunnel VPN: All traffic goes through the VPN gateway. Ensures policy enforcement.
Split tunnel VPN: Routes only specific traffic through VPN, improving speed but increasing risk.
Always-on VPN: Automatically connects at boot/login to enforce access control at all times.
Out-of-band (OOB) management: Dedicated physical channel for device recovery and management, separate from primary network.