The same sapp.toml exposes the RST-injection engine's tunable parameters directly: [stream.tcp.inject.rst] sets auto_remedy=1, number=1 (RST packets per kill), signature_enabled=1, and two numeric seeds (signature_seed1=65535, signature_seed2=13) that presumably drive an identifying pattern embedded in the injected RST packets themselves — i.e. the operator's synthetic RSTs are deliberately marked with a configurable signature, not raw/generic resets.
[stream.tcp.inject.rst] auto_remedy=1 number=1 signature_enabled=1 signature_seed1=65535 signature_seed2=13
Defense implications
- Since injected RSTs here carry a configurable, non-generic signature (seeded), a client that can fingerprint and selectively ignore RSTs matching this operator's signature (rather than all RSTs) could resist connection teardown without breaking legitimate reset handling — worth probing captured RSTs from this operator's networks for a consistent seed-derived pattern (e.g. in TCP window size, sequence offset, or option ordering).
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.
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.
An internal SAPP platform training/reference manual (marked "Geedge Networks Confidential And Proprietary") gives SAPP's full name as "Stream Analyse Process Platform" and documents its three-tier plugin architecture (platform / protocol-parsing / business layers, each loaded via dlopen), inline and mirror deployment modes at a stated 10-40 Gbps per box, tunnel-protocol support (GRE/MPLS/IPIP/IPv6-over-IPv4/Teredo), and the MESA_kill_tcp() plugin API that forges and sends RST packets to sever a monitored TCP connection, with the manual noting it was "originally used in mirror mode to send RST packets to block a TCP connection" and auto-retries until the connection is confirmed dead.
Geedge Networks' official 'Confidential and Proprietary' sapp developer manual documents sapp's platform-provided packet-injection API available to any business plugin: MESA_kill_tcp (crafts and sends a TCP RST matching the current flow's 4-tuple/sequence to force-terminate a TCP stream), MESA_kill_tcp_synack (sends a forged SYN/ACK in response to a client's SYN so the client cannot complete a handshake with the real server), and MESA_inject_pkt (injects arbitrary application-layer data into either side of an established flow).
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.
sapp's plugin API exposes explicit enforcement primitives -- MESA_kill_tcp()/MESA_rst_tcp() to inject a single RST, and MESA_set_stream_opt() with MSO_TCP_RST_REMEDY/MSO_DROP_STREAM to make RST-injection or packet-dropping persist for the remaining lifetime of a flow -- with a global sapp.toml auto_remedy toggle and a per-stream option controlling whether a lone RST is reinforced repeatedly for as long as the flow keeps sending data.