The tango/tfe-kmod repo is a DKMS Linux kernel module that reconstructs live TCP connections from out-of-band control messages (CMSG), using the TCP_REPAIR_WINDOW socket option to set window state without a handshake and adding special-case handling for protocols such as SSH where the server sends the first packet -- kernel-level infrastructure letting a userspace process ("TFE") transparently take over or inject into an in-progress TCP flow.

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.

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 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.

A 2023 MESA Lab monthly report (author and advisor names redacted) describes the 'TF' project's active-defense work: testing serial HTTP hijack/tamper and parallel DNS race-injection ('DNS抢答'), scaling active-defense compute boards from 3 to 5, converting two existing TSG units to active-defense mode, and rewriting active-defense flow control to no longer depend on sapp. NOTE: this content is nearly identical to the existing corpus finding 2026-084104-tf-active-defense (artifact 084104aa052e) -- likely the same underlying document ingested under two different artifact IDs; flagged for dedup review.

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).

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.