A large mobile telephony and data network operator has a data that houses network elements. These are essentially large computers running on Linux. The perimeter of the data center is secured with fir

Hardening each Linux-based network element with strong credentials, minimal user accounts, and regular security testing applies the principle of defense-in-depth. Perimeter firewalls and IPS systems protect the boundary but cannot stop threats that originate from within the network or from a compromised perimeter device, so host-level hardening is a required complementary control.

Physical access restrictions alone do not address logical attacks such as remote exploits, credential theft, or insider threats that can reach network elements through legitimate network paths.

Firewalls and IPS are perimeter controls and do not protect against threats already inside the network, misconfigurations on the host, or vulnerabilities in the OS and services running on the network elements themselves.

Assuming downtime is inevitable and relying solely on a backup site is a reactive continuity strategy, not a proactive security policy, and does not address the prevention of attacks or the hardening of assets.