TSG implements heuristic tunnel-protocol detection distinguishing Teredo (IPv6-over-UDP, default port 3544) from GTP tunneling based on UDP payload inspection, used to decide 'innermost' session attribution for firewall matching.
sapp存在将dns数据包误识别为teredo隧道的情况...加上对默认端口（UDP 3544）的判断以增强准确性
Defense implications
- Tunneling protocols that mimic or default to Teredo's standard port are subject to specific heuristic misclassification logic -- worth testing whether non-standard-port variants evade this.
Related findings
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.
Crash-dump stack traces reveal TSG's core packet-processing engine (sapp) architecture: a custom multi-threaded C engine using 'marsio' as the DPDK-style packet-I/O driver, a plugin system for protocol handlers (confirmed: plug/protocol/http/http.so), and a libdocumentanalyze component that actively decompresses gzip content and parses ZIP/document formats found inside HTTP bodies -- i.e. inspection goes beyond headers into reconstructed application content.
An official "Geedge Networks Confidential And Proprietary" sapp/mrzcpd operations manual documents the packet-injection API (MESA_kill_tcp / MESA_inject_pkt) used for both out-of-band mirror-tap RST injection (relies on the local box's own IP routing table to send) and inline in-path injection (requires mrtunnat.conf tunnel-tracking state -- use_recent_tunnel, use_link_info_table -- keyed on outer/inner MAC and link_id/link_dir), plus the Marsio DPDK-based driver's I/O sub-modes (marsio4, marsio_vxlan, pag_marsio, agent_smith) and its role extracting VXLAN/GTP encapsulation metadata and stamping link/circuit identifiers into mirrored packets' MAC field for session-log correlation.
A June 2021 MESA Lab test report ("精管流量初步分析报告") measured a live TLS-decryption pipeline feeding two sapp instances -- sapp A ingesting raw encrypted traffic via mrzcpd, sapp B ingesting plaintext from a third-party decryption platform over a Unix domain socket -- and found decrypted plaintext covered only 4.85% of raw traffic bytes and 7.4% of port-443 connections, with average MITM decryption latency of 1741ms (range 158-6000ms) across 2957 matched connections.
A June 2023 MESA engineering report on "TF项目" ("project TF") documents TSG configuration changes alongside CM and OLAP components, and explicitly records resolving a "hijack-injection function" (劫持注入功能) interface issue where policy was not taking effect, followed by completed hijack-effect verification and active-defense (主动防御) effect verification -- naming two further internal tools, netflood and houyi, used alongside sapp for packet injection, plus a git.mesalab.cn/active-defense repository.
The internal 'MAAT网络流处理配置统一描述框架' engineering manual (v3.1.20, author 郑超, 2021) documents MAAT's Redis-synced rule-compilation framework and its RuleScan/Hyperscan-based pattern-matching engine (libmaatframe.so / librulescan), and records that RuleScan's fast-scan feature caused a production outage on 2019-03-19 and has been disabled ever since.