# Network Protection

***

## **1. Network Segmentation**

**Purpose**: To isolate critical systems and limit the spread of breaches within the network.

* **Why**: If a breach occurs, network segmentation ensures that attackers cannot easily move laterally across the network, thereby protecting sensitive or business-critical systems.
* **Technical Example**:
  * Use VLANs (Virtual Local Area Networks) to segment different parts of the network:

    ```bash
    vlan 10
    name CriticalSystems
    exit
    interface GigabitEthernet0/1
    switchport access vlan 10
    ```
  * Apply firewall rules to restrict traffic between segments:

    ```bash
    access-list 100 permit ip 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255
    ```

    * This rule allows only specific IP ranges to communicate, ensuring that connections are permitted only as required by the business.
* **Internal Resources and DMZ**:
  * Internal resources should not face the internet directly unless placed in a **DMZ (Demilitarized Zone)**. For example:
    * Place web servers or external-facing applications in the DMZ while keeping internal databases and critical systems behind an additional layer of security.
    * Configure firewall rules to allow only necessary traffic from the DMZ to internal networks:

      ```bash
      access-list 110 permit tcp 192.168.3.0 0.0.0.255 192.168.1.0 0.0.0.255 eq 80
      ```

***

## **2. IDS/IPS Systems with SSL/TLS Interception**

**Purpose**: To detect and block malicious traffic based on content rather than relying on IP reputation.

* **Why**: Traditional methods of detecting malicious traffic based on IP reputation are inefficient because attackers frequently change IPs. SSL/TLS interception allows IDS/IPS systems to inspect encrypted traffic for malicious payloads.
* **Technical Example**:
  * Deploy an IDS/IPS system like **Snort** or **Suricata** with SSL/TLS decryption capabilities:
    * Install the IDS/IPS appliance and configure it with a decryption certificate to intercept SSL/TLS traffic.
    * Define rules to detect malicious content:

      ```bash
      alert tcp any any -> any any (msg:"Malicious Payload Detected"; content:"evil_payload"; sid:1000001;)
      ```
    * Ensure that the IDS/IPS is configured to inspect decrypted traffic for known malicious patterns or behaviors.

***

## **3. Device Authentication with 802.1x**

**Purpose**: To ensure that only organization-approved devices can connect to the corporate network.

* **Why**: Unauthorized or personal devices (BYOD) can introduce vulnerabilities. **802.1x** provides network access control by authenticating devices before granting access.
* **Technical Example**:
  * Configure **802.1x** on network switches using RADIUS authentication:

    ```bash
    aaa new-model
    aaa authentication dot1x default group radius
    dot1x system-auth-control
    interface GigabitEthernet0/1
    dot1x port-control auto
    ```
  * Only devices with valid credentials (e.g., certificates or usernames/passwords) will be allowed to connect to the network.

***

## **4. Conditional Access Policies in Cloud Environments**

**Purpose**: To enforce device compliance and ensure that only company-managed devices can access organizational resources in cloud-only environments.

* **Why**: In cloud environments, traditional network perimeters do not exist. Conditional Access policies help enforce security by requiring devices to meet certain criteria (e.g., being managed by the organization) before accessing resources.
* **Technical Example**:
  * In **Azure AD**, create a Conditional Access policy to restrict access to resources:
    1. Navigate to **Azure Active Directory > Security > Conditional Access**.
    2. Create a new policy:
       * **Assignments**: Select users or groups that this policy applies to.
       * **Conditions**: Require the device to be marked as "compliant" or "domain-joined."
       * **Access Controls**: Block or grant access based on the conditions.
    3. Example Policy:
       * **Name**: "Restrict Access to Company-Managed Devices"
       * **Conditions**: Require the device to be compliant.
       * **Access Controls**: Block access if the device is not compliant.

***

## **Conclusion**

By implementing **network segmentation**, deploying **IDS/IPS systems with SSL/TLS interception**, enforcing **device authentication via 802.1x**, and leveraging **Conditional Access policies** in cloud environments, organizations can significantly enhance their network protection. These measures collectively reduce the attack surface, prevent unauthorized access, and ensure that even if a breach occurs, its impact is contained.

Each of these techniques provides a layer of defense that, when combined, creates a robust network security posture.
