Internal MAAT engineering specification (v3.1.20, MESA Lab, revision history spanning 2014-2021) documents the config schema underlying sapp's rule-matching engine: per-rule action types (0=block/阻断, 1=monitor/监测, 2=whitelist/白名单), string/regex/IP/numeric/digest match types, and a geographic+ISP "tag" targeting system that lets the identical rule set be selectively activated per city district and carrier (e.g. Beijing/Chaoyang + China Telecom vs. Shanghai/Pudong), enabling narrowly-scoped rule rollout/testing before wider deployment.
动作 action VARCHAR(1) N 推荐定义:0:阻断，1：监测，2：白名单 ... {"tag_sets":[[{"tag":"location","value":["北京/朝阳/华严北里","上海/浦东/陆家嘴"]},{"tag":"isp","value":["电信","移动"]}],[{"tag":"location","value":["北京"]},{"tag":"isp","value":["联通"]}]]}
Defense implications
- MAAT's block/monitor/whitelist action model plus its region+ISP tag targeting means a censor can trial a new keyword/IP rule in a single city+carrier before nationwide rollout — treat a geographically-isolated blocking report as evidence of a live A/B test, not proof a technique won't scale nationally.
Related findings
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.
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.
Side-by-side internal performance comparison across Xinjiang (China Mobile carrier deployment, hostname cmcc-xj-server1-sapp-244), Fujian (domestic), and Ethiopia (E21) explicitly references the same 'app_sketch_maat' diagnostic log format at all three sites, confirming the identical AppSketch app-fingerprinting stack is used for domestic Xinjiang surveillance and for the exported Ethiopia deployment.
TSG's DPI signature engine is organized around named internal components confirmed by config paths and error logs: SAPP (installed at /home/mesasoft/sapp_run or /opt/tsg/sapp), MAAT (config at .../tsgconf/maat.conf, tied to a Redis-backed APP_SIG_SESSION_ATTRIBUTE_STRING table), and App-SketchDB (a versioned, centrally-maintained app-identification signature database pulled periodically by field deployments). One deployment's provincial gateway alone had 1,667 TCP/UDP first-packet payload signature entries active (396 at the IDC site), confirming payload-prefix matching as a live, large-scale detection method, including custom byte-prefix entries for DingTalk and WeChat.
Leaked per-app JSON signature-rule exports show the detection engine layers multiple independent signals per VPN product: Windscribe VPN is matched via fixed-offset hex-byte keywords inside the OpenVPN UDP handshake payload (offset 73/depth 78 and offset 81/depth 85); "Super Unlimited VPN" (the SuperUnlimitedVPN app) gets three parallel signatures — a JA3 TLS-fingerprint match, an FQDN match, and an OpenVPN c2s-payload-prefix/length match; Hide.me VPN is matched on OpenVPN UDP payload; FastVPN is matched purely by known source/destination IP; and "V2VPN" (Google Play com.v2ray.v2vpn, a V2Ray-based VPN app) has its own dedicated signature — evidencing a deliberately layered (protocol-fingerprint + TLS-fingerprint + FQDN + IP) detection strategy per circumvention product.
An internal 'MAAT Configuration Description Manual (String)' fully documents MAAT's rule-compilation model: per-field string matches (substring/prefix/suffix/exact/regex/AND-of-substrings/offset-anchored substrings) grouped into up to 8 AND/NOT clauses per compiled rule (conjunctive normal form), each carrying an action code (0=block, 1=monitor-only, 2=whitelist), blacklist and logging flags, and a floating-point execution-order field for safe rule reordering, plus the C scanning API (Maat_full_scan_string) and the file/JSON formats used to push rule updates to production.