When deploying CN2 servers in Japan, port configuration ensures reliable network connectivity and efficient data exchange. The CN2 backbone network, with its low latency, low packet loss, and QoS priority, offers inherent advantages for cross-border business, real-time communications, and high-concurrency access scenarios. However, improper port policy configuration can still lead to security vulnerabilities such as connection timeouts and bandwidth waste.
Service types and protocols should be categorized: Web services primarily rely on TCP 80 and 443; databases commonly use 3306 and 5432; SSH operations and maintenance default to 22; live streaming services often use high-performance UDP ports 16384 and above; internal ports such as APIs, message queues, and caches should also be considered. In principle, a "minimum available" strategy should be followed, opening only necessary ports and implementing granular source address control through firewall whitelists, ACLs, and security groups.
At the network level, backhaul optimization for CN2 servers is performed by the carrier by default, but administrators still need to manage the entry point. By configuring INPUT and OUTPUT chain rules using iptables or nftables, you can implement granular rate limiting, connection limit, and abnormal behavior drop for port traffic. For example, you can enable syn-flood protection on port 443 to limit the handshake rate for the same-source IP address. For port 22, add failed login blocking logic and dynamically update the blacklist with fail2ban to prevent brute force attacks. If your server hosts multiple tenants or microservices, you can use Linux namespaces or the control group-based net_cls module to assign different service ports to independent network spaces. This reduces the risk of port conflicts and allows for traffic statistics and dynamic bandwidth quota adjustments based on service levels.
For scenarios requiring large amounts of data exchange, such as file distribution, real-time streaming, or database replication, common bottlenecks are port queues and window sizes. You can adjust parameters such as net.core.somaxconn, net.ipv4.tcp_tw_reuse, and net.ipv4.tcp_rmem through sysctl to expand the queue buffer and reduce the accumulation of TIME_WAIT states. For UDP applications, pay attention to net.core.rmem_max and net.core.wmem_max to avoid packet loss at high bandwidth. The CN2 network inherently has low latency. Inefficient port handshake and ACK processing will weaken the line's advantages. Therefore, it is necessary to use a monitoring platform to monitor RTT, Retransmit, and Out-of-Order metrics in real time to adjust kernel stack parameters and application-layer threading modes in a timely manner.
SSL terminal mapping is a key method for CN2 servers to handle overseas clients. By enabling TLS 1.3 on port 443 and implementing multi-certificate traffic distribution at the Nginx or HAProxy layer, you can ensure efficient HTTPS access for multiple domains. To reduce handshake latency, you can enable 0-RTT or Session Resumption. For long-connection services like WebSocket and gRPC, the keepalive timeout should be relaxed to reduce port usage caused by frequent reconnections. The number of active channels in the connection pool should also be monitored to ensure port exhaustion is not triggered.
In containerized deployments, Kubernetes or Docker defaults to forwarding high-order ports to each pod/NAT server. This multi-level mapping can easily lead to random port allocation conflicts in high-concurrency scenarios. It is recommended to use hostNetwork or load balancing ingress fixed ports on CN2 servers to explicitly map external access to internal pod ports. Maintaining a unified access layer through a service mesh or LVS/IPVS reduces additional forwarding overhead.
For cross-border database synchronization, use bidirectional whitelisted ports 3306/5432 and enable SSL/TLS channels to prevent link snooping. CN2 lines have a higher MTU, which can appropriately increase the TCP MSS and window ratio, optimizing the transmission efficiency of large data blocks. When using rsync+ssh for backup channels, a dedicated QoS should be configured for port 22 to prevent scheduled backups from consuming bandwidth and impacting online transaction port throughput.
Security is crucial. DDoS attacks often exploit open ports for SYN or UDP floods. While the CN2 High Defense plan can clean traffic, local servers still need to be configured with SYN cookies, connection thresholds, and UDP fragment limits. Externally exposed services must have a WAF enabled, combined with ModSecurity or NAXSI to block malicious requests to ports 80 and 443 in real time. Internal management ports should use private networks, restricting access to only the designated operations and maintenance network segment. When connecting to vendor APIs, use mTLS or signature mechanisms to prevent key leaks that could lead to arbitrary port access spoofing.
Port monitoring on CN2 servers is also crucial. Use solutions such as Netdata, Prometheus + node_exporter, and ELK to generate real-time statistics on port connections, byte rates, and error codes. Use ipset's dynamic blacklist feature to automatically block abnormal scanning IPs, and use fail2ban's custom filters to block them. Send SMS or webhook alerts for abnormal connections to critical ports to ensure prompt intervention by the operations and maintenance team.
In the CN2 server environment in Japan, port research and management must consider both performance and security. We prioritized the minimum set of ports required for business needs and optimized the operating system kernel to improve concurrency efficiency. We also established firewall rules, implemented internal and external network separation strategies, and implemented continuous monitoring to minimize risk. We optimized the entire process, from port planning, kernel parameters, application-layer throttling, and defense systems, to unleash the advantages of CN2's low latency and high bandwidth.
