Network security is the collection of technological, administrative, and physical measures designed to protect the confidentiality, integrity, and availability of data transmitted over computer networks. These measures aim to protect the network against both internal and external threats. It requires taking precautions against attack types such as unauthorized access, data loss, identity fraud, and service disruption that may affect institutions, individuals, and systems. Network security ensures the safe operation not only of information technology infrastructure but also of economic, social, and administrative activities.

Assets to Be Protected

There are three fundamental assets to be protected in network security:

• Data: Information must be protected based on its confidentiality, integrity, and availability. For example, if a file is viewed by unauthorized persons (confidentiality breach), modified (integrity breach), or becomes inaccessible (availability breach), it poses a security problem. Data protection is critically important especially for public institutions, financial organizations, the healthcare sector, and educational institutions.
• Resources: The misuse of system components such as computers, servers, and network hardware also constitutes a security issue. Unauthorized access to these resources may affect system performance or cause data leaks. Physical resources such as memory, CPU power, and storage units can be hijacked by malicious users and used for various attacks.
• Reputation: The reputation of institutions or individuals may be damaged through attacks on their systems. Malicious use of compromised systems can undermine the trustworthiness of the institution. This is particularly significant for public service institutions and private companies that risk losing user confidence.

Types of Attacks

Attacks on networks are divided into two main categories:

• Passive Attacks: These involve monitoring data transmission without interference (e.g., traffic analysis, eavesdropping). They are difficult to detect and primarily violate confidentiality. Such attacks are commonly observed in environments with inadequate secure communication protocols.
• Active Attacks: These involve direct interference with data transmission, such as data modification, message spoofing, or denial-of-service (DoS) attacks. They primarily target system integrity and service continuity. Effective monitoring and anomaly detection are required.

Core Security Services

• Authentication: Verifies whether a user or system truly possesses the claimed identity. It is typically achieved through username-password combinations, biometric data, or digital certificates.
• Access Control: Determines who can access what, when, and how. Access control should be supported by physical, logical, and administrative mechanisms.
• Confidentiality: Ensures that data is accessible only to authorized individuals. This is achieved through methods such as encryption and access control.
• Integrity: Guarantees that data arrives unaltered after being sent. Hash algorithms and digital signatures play an essential role in this context.
• Non-repudiation: Ensures that neither the sender nor the receiver can deny their actions later. This assurance is critical for legal operations and the protection of sensitive records.

Security Measures and Tools

• Firewalls: The primary defense mechanism that filters traffic between internal and external networks. They operate using techniques such as packet filtering, application gateway, and stateful inspection. Available in both hardware and software forms.
• VPN (Virtual Private Network): Provides secure communication over public networks. It protects data transmission through encrypted tunnels.
• Intrusion Detection Systems (IDS): Detect suspicious activity on the network and provide alerts. They allow for analysis before and after an attack.
• Cryptography: Enables encrypted data transmission using symmetric and asymmetric algorithms. It is essential for ensuring data confidentiality and integrity.
• Antivirus and Antimalware Software: Protect systems from malicious software. They are regularly updated to defend against new threats.
• Social Engineering Precautions: Training and awareness are necessary to reduce human-induced risks. Measures are taken to prevent users from being deceived by phishing, fake emails, and fraudulent calls.

Security Policy and Risk Management

In addition to technical measures, network security must be supported by internal organizational policies. Rules such as authorization matrices, user access controls, password policies, and usage protocols should be clearly defined and enforced. Furthermore, risk analysis should be conducted to identify weak points in the system in advance and to implement necessary countermeasures. Risk analysis includes determining the value of assets, potential threats, vulnerabilities, and the possible damage in case these vulnerabilities are exploited.

Network security is a fundamental necessity for ensuring the safety of institutions and individuals in the information age. Effective network security is achievable not only through software and hardware but also through user awareness and institutional policy. Security is a dynamic process that requires continuous monitoring, updating, and auditing. In this context, security solutions must be approached holistically, and physical, technical, and administrative measures should be considered together.