Network security is a critical aspect of blockchain architecture, ensuring the integrity and confidentiality of the network and its data. Some measures to protect the network from attacks include:

1. _Firewalls_: Configuring firewalls to control incoming and outgoing network traffic.

2. _Encryption_: Using encryption algorithms like SSL/TLS, AES, and PGP to protect data in transit.

3. _Access Control_: Implementing access control mechanisms like multi-factor authentication, role-based access control, and least privilege access.

4. _Intrusion Detection and Prevention Systems (IDPS)_: Monitoring network traffic for suspicious activity and blocking potential threats.

5. _Node Validation_: Validating node identities and ensuring only authorized nodes participate in the network.

6. _Smart Contract Security_: Implementing secure coding practices, testing, and auditing for smart contracts.

7. _Regular Security Audits and Testing_: Performing frequent security assessments and penetration testing.

8. _Secure Key Management_: Managing and protecting private keys and cryptographic materials.

9. _Network Segmentation_: Dividing the network into smaller segments or sub-networks for improved security.

10. _Incident Response Planning_: Establishing procedures for responding to security incidents and breaches.

11. _User Education and Awareness_: Educating users about security best practices and the importance of security.

12. _Compliance with Regulations_: Adhering to relevant security standards and regulations, such as GDPR and HIPAA.

By implementing these measures, blockchain networks can protect against various threats and maintain the trust and integrity of the network.