The same change document's post-deploy validation step explicitly checks that "spoofed packets and RST packets" are generated normally with no volume anomaly as routine production behavior, and the release separately adds a feature to retain full email body content (not just metadata) on business-user request, running on Kylin Linux Advanced Server V10.
前端欺骗包与RST包正常产生，量无异常波动 满足业务用户提出的邮件正文内容留存需求
Defense implications
- Confirms DNS/content spoofing and RST injection operate concurrently as standard, continuously-monitored production behavior (not an either/or choice), and that surveillance depth (metadata-only vs. full content retention) is itself a configurable, business-request-driven knob rather than a fixed policy.
Related findings
TSG's firewall 'Deny' security-policy action is confirmed implemented via three interchangeable mechanisms: TCP RST injection, forged HTTP 404 response-page injection, and DNS-redirect. Confirmed via commits to MESA_Platform/sapp and tsg/tsg-os-buildimage GitLab repos (git.mesalab.cn).
The official SAPP platform manual ("Geedge Networks Confidential And Proprietary") documents an optional signature_enabled config flag that stamps sapp-injected TCP RST packets with a detectable pattern in the ip_id/ip_ttl/tcp_win fields so operators can later verify, via a Wireshark plugin or standalone tool, whether a given RST originated from a sapp instance -- the manual explicitly notes 100% recall but not guaranteed 100% precision. The manual separately documents that sapp supports three distinct wire-injection topologies (sys_route, vxlan_by_inline_device, raw_ethernet_single_gateway) and that its tcpdump_mesa debug tool has a dedicated "inject" packet class covering both TCP RST and forged DNS replies.
An internal TSG operations/troubleshooting manual lays out TSG's full traffic pipeline (NIC -> mrzcpd/marsio capture driver -> sapp DPI engine -> firewall/proxy(KNI->TFE)/active-defense/WAN-NAT policy branches) and shows engineers using maat_redis_tool to pull the live Redis-synced blocking policy tables (TSG_SECURITY_COMPILE, TSG_OBJ_IP_ADDR, TSG_OBJ_APP_ID) and filter them by numeric policy/object ID to debug why a block rule isn't firing.
Raw structured DNS event logs (dated 2021-08-23) captured from what appears to be a GFW-adjacent DNS monitoring/injection pipeline use a schema purpose-built for DNS response forgery ('CHEAT_TYPE', 'CHEAT_RCODE', 'CHEAT_STRATEGY', 'CHEAT_RR', 'INJECTED_PKT_FILE' fields) alongside per-query geolocation; sampled records show lookups for facebook.com and tiktokv.com originating from residential China Telecom/Unicom/Mobile subscriber IPs in Guangdong, Zhejiang, Anhui and other provinces, resolving against both domestic and foreign (8.8.8.8, OpenDNS) resolvers.
A 2023 MESA Lab monthly report describes the 'TF' project's active-defense work: test cases for serial ('串联') HTTP hijack/tamper and parallel ('并联') DNS race-injection ('DNS抢答'), performance tuning that scaled active-defense capacity from 3 to 5 units, converting two existing TSG boxes to active-defense mode, and rewriting the active-defense flow-control logic to no longer depend on sapp.
The same SAPP manual documents mrzcpd's inline (串联) packet-re-injection subcomponent mrtunnat, configured at /opt/mrzcpd/etc/mrtunnat.conf: use_recent_tunnel=1 allows it to inject a packet with no prior session record, and use_link_info_table=1 makes it validate outer MAC, link_id, link_dir, and inner MAC against a live link-state table at /run/mrzcpd/mrmonit.tunnat before re-injecting a censor-forged packet onto the correct physical link.