Security Protection And Ddos Mitigation Strategies When Deploying Cn2 In Los Angeles, Usa

1.

overview and deployment goals

- goal: ensure that the business directly connected to china through cn2 on the los angeles node is stable and available.
- risk points: ddos (syn/udp/http flood), route hijacking, connectivity jitter.
- requirements: response delay ≤120ms (for users in eastern china), and can withstand common attack peaks ≥20gbps.
- constraints: bandwidth costs, compliance and port policies need to be coordinated with the isp (cn2).
- output: provide end-to-end protection architecture, system parameters and emergency procedures.

2.

network and topology design

- multi-line bgp: the main link is los angeles cn2 direct connection, and the backup link is aws/alibaba cloud multi-region.
- static/dynamic routing: bgp announces priority settings to avoid single-point loops.
- edge cleaning: deploy cleaning nodes at upstream access points (or cooperative isp cleaning centers).
- cdn front-end: use cdn for static content (enable caching and rate limiting).
- load balancing: l4/l7 load balancing is offloaded to the backend pool, combined with health checks.

3.

host and system configuration examples

- physical/vps example: cpu 8 cores, memory 32gb, disk nvme 500gb, bandwidth 500mbps without current limit.
- operating system: ubuntu 22.04 lts, kernel 5.15+ (supports bpf and better network stack).
- kernel tuning (example): net.core.somaxconn=65535; net.ipv4.tcp_syncookies=1; net.netfilter.nf_conntrack_max=2000000.
- firewall/process: use nftables/iptables + conntrack, enable fail2ban, syslog centralization.
- service software: nginx 1.22 (worker_processes auto), enable limit_req_zone and limit_conn.

4.

ddos mitigation strategies and rules

- upstream cleaning link: negotiate the cleaning level (such as 5gbps/20gbps/100gbps) with the isp and set the trigger threshold.
- application layer current limit: nginx limit_req (example: 10r/s), limit_conn (example: 200 concurrency).
- network layer filtering: iptables example rule (drop syns from a single source that exceed the threshold): -m connlimit/--connlimit-above.
- syn cookie and rate limiting: enable tcp_syncookies and use tc to shape udp traffic.
- cdn and waf: statically go to cdn, and dynamic api filters abnormal requests through waf (rule base + js/challenge).

5.

monitoring, alarm and emergency procedures

- indicator monitoring: traffic (gbps), number of connections, rps, packet loss rate, delay.
- alarm threshold: inbound traffic >500mbps or the number of connections increasing >300% triggers a secondary alarm.
- automated response: automatically enable upstream cleaning, switch to backup link, and limit unauthenticated traffic when triggered.
- manual handling: security engineers respond within 15 minutes and upgrade to isp cleaning/black hole routing.
- event review: retain pcap and netflow for attack feature extraction and rule implementation.

6.

real cases and effect data

- case background: during the double eleven period in 2025, a cross-border e-commerce company encountered a mixed traffic attack (udp+http) on its cn2 node in los angeles.
- initial impact: inbound peak traffic reached 18.6gbps, the number of connections instantly reached 1.2m, and user p99 latency soared to 780ms.
- disposal process: trigger automatic cleaning (cooperating with isp), and enable cdn challenge page and nginx current limiting at the same time.
- recovery effect: cleaning is in place within 5 minutes, and business availability is restored to 99.95%.
- learning point: defining cleaning slas and thresholds in advance, combined with application current limiting, can significantly shorten recovery time.

7.

performance and protection comparison data (example)

8.

conclusion and recommendations

- preconfiguration: it is recommended to sign the cleaning and bgp grayscale policies with cn2 in advance before deployment.
- multi-layer protection: combining cdn, waf, edge cleaning and host-level current limiting to form defense in depth.
- traffic drills: conduct regular drills to verify the effectiveness of cleaning slas and automation scripts.
- data retention: save attack traffic samples for signature database updates.
- continuous optimization: adjust thresholds, rules and routing strategies based on logs and netflow.