Overseas server security is critical to maintaining business continuity and data integrity. Faced with an increasingly complex cyber threat landscape, systematic security hardening measures and attack protection solutions are necessary to build a multi-layered defense system.

System-level security hardening. Operating system security is the first line of defense for overseas servers. Keeping systems up-to-date is crucial; regularly install security patches and upgrade software versions. For Linux systems, configure automatic security updates:

apt-get install unattended-upgrades
dpkg-reconfigure -plow unattended-upgrades

Also, enable security subsystems such as SELinux or AppArmor to restrict service permissions. User account management should be strictly regulated, disabling remote root login, enforcing key authentication, and implementing a strong password policy:

PermitRootLogin no
PasswordAuthentication no

Network service exposure should be minimized. Use firewalls to strictly control port access, allowing only essential service ports to be accessible externally. Example iptables configuration:

iptables -A INPUT -p tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -j DROP

For web services, changing the default port and hiding version information can effectively reduce targeted attacks. Regularly perform vulnerability scanning and penetration testing to promptly identify and remediate security vulnerabilities.

Deploy a real-time intrusion detection system (IDS) such as Suricata or OSSEC to monitor abnormal network activity and file system changes. Configure centralized log management and use rsyslog or syslog-ng to transfer important logs to a dedicated overseas log server:

*.* @logserver:514

Set up real-time alerts to immediately notify administrators of critical events such as brute force attempts and unusual logins. Deploy integrity monitoring tools to monitor changes to critical system files and configurations.

Distributed denial of service attacks are a common network threat. At the network architecture level, use traffic scrubbing and blackhole routing technologies to mitigate large-scale traffic attacks. Deploy anti-DDoS devices or use cloud protection services, and set elastic bandwidth thresholds:

# Use iptables to limit the number of connections
iptables -A INPUT -p tcp --dport 80 -m limit --limit 100/min --limit-burst 200 -j ACCEPT

Application-layer DDoS protection requires special attention. Configure Web Application Firewall (WAF) rules to identify and block malicious requests. Implement rate limiting and human-machine authentication mechanisms to prevent resource exhaustion attacks.

Data transmission and storage require encryption. Enable TLS to encrypt all network communications, configure strong cipher suites, and regularly renew certificates. Database security requires special attention, implementing field-level encryption and access auditing:

# Configure SSL encryption for MySQL
require_secure_transport=ON

Backup data should also be stored encrypted, and backup integrity and recoverability should be regularly verified. Multi-factor authentication and privilege separation are recommended for critical data.

Develop a detailed security incident response process, clearly defining the steps and individuals responsible for handling various security incidents. Develop forensic analysis capabilities and preserve relevant logs and evidence. Conduct regular emergency drills to verify the effectiveness of the response plan and the team's response capabilities.

Establish a change management system, ensuring that all configuration changes are approved and documented. Implement the principle of least privilege, assigning appropriate access rights to different roles. Conduct regular security audits and risk assessments, and continuously optimize security policies.

The above multi-layered security measures can significantly enhance the security capabilities of overseas servers. However, it's important to note that security protection is an ongoing process, requiring regular evaluation and adjustment of security policies to adapt to the ever-changing threat landscape. Furthermore, strengthening security awareness training and improving the security capabilities of the entire team is crucial to building a truly effective security defense system.