Sharing Experience In Configuring Korean Native Ip Adapter Equipment And Common Network Environments

1. overview: why use korean native ip and the difficulties in adaptation

1) using korean native ip can improve local access speed, reduce cdn return delay and improve geolocation accuracy.
2) common difficulties include inconsistency between ip attribution and geoip, reverse dns/ptr not configured, and poor quality of interconnection with local isp.
3) devices (routers, load balancing, iot terminals) may need to adjust mtu, nat and routing policies to adapt to native ip.
4) regulations and compliance: when deploying services in south korea, you need to pay attention to regulations related to personal information and communications (example: local data backup policy).
5) goal: taking into account speed, availability and attack resistance, provide reproducible configuration examples for engineers to get started quickly.

2. ip allocation, bgp and dns strategies (practical points)

1) if you use your own asn or lease a korean segment ip, you should establish bgp peering with the local operator and set the local egress priority first.
2) the reverse dns (ptr) must be consistent with the domain name resolution so that the email service can avoid being marked as spam. example: ptr: mail.example.kr -> mail.example.kr.
3) geoip database update frequency: maxmind/ip2location is synchronized every month. it is recommended that operators regularly verify and submit correction requests.
4) dns settings: the primary dns is in south korea, the secondary dns is backed up off-site, and the ttl policy recommends that business records be recorded for 60-300 seconds for switching.
5) nat and source address retention: if you use a nat gateway, please note that source address retention (snat) will affect the return connection. if necessary, enable static nat or vip.

3. device and operating system network optimization (key parameters and command examples)

1) mtu/mss adjustment: some isps in south korea have restrictions on vpn/tunnel mtu. common commands: ip link set dev eth0 mtu 1500. if there are fragmentation problems, try 1460.
2) tcp optimization: adjust tcp_tw_recycle/tcp_tw_reuse (modern kernels recommend only tcp_tw_reuse), example sysctl setting: net.ipv4.tcp_fin_timeout=30.
3) connection tracking and concurrency: the conntrack table size should be calculated based on concurrency, example: net.netfilter.nf_conntrack_max=524288.
4) kernel parameters and i/o: net.core.somaxconn=1024, net.ipv4.tcp_max_syn_backlog=2048. use sysctl -p to load.
5) logging and debugging: use ss -tn state syn-recv to view syn flooding; tcpdump -i eth0 host xxxx for packet capture and location.

4. server/vps configuration examples and performance data (sample table)

1) the following are two typical host configuration examples for the korean market (for production environments, please press business expansion).
2) the example includes cpu, memory, disk, bandwidth and operating system information for quick reference and comparison.
3) actual measurement: using iperf3 from south korea to overseas nodes, the peak single tcp throughput is about 800mbps (1000mbps link) and the delay is 35ms.
4) nginx and keepalived implement vip high availability. example keepalived priority settings: master priority 150, backup 100.
5) table display (sample data, for reference only):

example	cpu	memory	disk	bandwidth	system/remarks
vps - small (example)	2 vcpus	4gb	50gb ssd	1 gbps share	ubuntu 22.04, suitable for lightweight api
physical - high availability (example)	8 corexeon	32gb	2 x 1tb nvme (raid1)	10 gbps dedicated link	centos/almalinux, recommended for high-concurrency services

5. cdn, domain name resolution and gslb strategy (acceleration and disaster recovery)

1) cdn selection: give priority to manufacturers with korean pops (for example, with seoul nodes), and enable anycast, http/2, and quic support to reduce rto.
2) back-to-origin strategy: use long connection back-to-origin for dynamic interfaces and enable cache layering (edge cache + origin cache-control) to reduce back-to-origin pressure.
3) gslb (global load balancing): configure traffic scheduling based on delay and health check, and set ttl low for switching (60 seconds).
4) domain name registration/registration: when providing services in south korea, ensure that the domain name information is consistent with whois and configure dnssec (if necessary).
5) example: using cloudflare + local korean node combination, static resources go through cdn, and api goes back to the local vip to ensure low latency.

6. ddos protection and real response cases (steps and configuration recommendations)

1) multi-layer protection: edge cdn resists small traffic/application layer attacks, backbone bandwidth and bgp black hole handle large traffic, server-side current limiting and waf protect the application layer.
2) blocking strategy: set ipset + nftables/iptables blacklist and combine with fail2ban to automatically block malicious ips. example: connlimit and limit rules.
3) monitoring and alarming: collect traffic (sflow/netflow), number of connections, cpu/memory, i/o and set threshold alarms (for example, triggered by traffic >500mbps).
4) real case: a korean e-commerce company suffered a burst traffic attack. it used cdn to absorb large traffic (peak value: 5.2gbps). at the same time, it enabled bgp blackhole on the backbone side and switched to the backup cloud back to the origin. the business was restored within 3 minutes.
5) drill suggestions: conduct failover and ddos drills regularly, and save traceback logs and pcaps for post-analysis and communication with operators.