For mirror/passive-tap deployments (Xinjiang trial-bureau and Fujian projects), TSG-OS could not send blocking (reset/deny) packets out via a management NIC in the then-current container-mode build — SAPP's generated blocking packets could only be re-injected inline via mrzcpd. This was filed as a required feature (accepted by a CTO-level engineer (name redacted) for the TSG23.07 release) confirming the deployment architecture is out-of-path traffic mirroring plus injected reset packets, i.e. classic side-channel RST-injection censorship, for at least these two sites.

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.

TSG ships a built-in offensive "active defense" (主动防御) module named houyi (后羿), built on the sapp/marsio/mrzcpd stack, that performs spoofed-source-IP network-layer flood attacks, DNS/NTP/Memcached reflection-amplification attacks, and application-layer (HTTP/HTTPS) CC floods against a configured target. Spoofed source IPs are drawn from named CIDR-range "profiles" (e.g. 10.1.1.0/24), and policy is distributed via Redis and issued either through an interface called "安天" (Antiy) or by directly calling a "毕方" (Bifang) API. Deployment is via Ansible from git.mesalab.cn/tsg/houyi-deploy, packaged as RPMs installed under /opt/houyi and as sapp plugins under /home/mesasoft/sapp_run/plug.

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.

Geedge's production inline-deployment container bundle (tango/tsg_container) wires mrzcpd (capture/inject), sapp (DPI via maat rules), and a third component "tfe" (traffic-forwarding engine) together via Docker Compose; tfe ships a dedicated doh.conf (DNS-over-HTTPS handling) and the firewall-mode container's sapp config includes a send_raw_pkt.conf, a KNI (kernel network interface) config, an "asymmetric_presence_layer.conf" for mirror/asymmetric-routing deployments, and a "pangu" proxy module (pangu_pxy.conf / pangu_http.json).

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.

A "精管流量初步分析报告" (2021-07-26) documents a live paired-sapp TLS-interception testbed: sapp instance A captures raw ciphertext via mrzcpd/PAG while sapp instance B ingests plaintext from a third-party decryption platform over a Unix domain socket. The report measures decryption latency (mean 1.82ms), completeness (only 44% of connections flagged decryptable via an SSL/TLS ClientHello-based "user legitimacy" check were actually decrypted, and 88% of eligible users), and confirms RST-based blocking triggered from the decrypted side reaches the client in a median ~0.5ms and successfully blocked live access to Facebook, Wikipedia, Twitter, the New York Times, and Google (BBC was the one tested site that evaded blocking). The decrypted side also resolves each session to a persistent per-user ID via the ciphertext side's four-tuple lookup.