suppress ipv6 noise between veth interfaces

backend/src/network_sniffer.py

@@ -491,6 +491,15 @@ def _sync_bridge_telemetry() -> None:
         logger.exception("Failed to update bridge telemetry collector")
 
 
+def _managed_capture_ifaces() -> set[str]:
+    return {
+        iface
+        for session in sessions.values()
+        if session.get("is_bridge")
+        for iface in session.get("capture_ifaces", [])
+    }
+
+
 # -------------------------
 # Per-session reader loop
 # -------------------------
@@ -570,6 +579,9 @@ def _session_reader_loop(session_id: str) -> None:
                     packet_bytes = raw
                     if settings.capture_header_enabled:
                         capture_meta, packet_bytes = parse_capture_header(raw)
+                    if capture_meta is None and iface in _managed_capture_ifaces():
+                        logger.debug("Skipping unshimmed packet on managed capture interface %s", iface)
+                        continue
                     pkt = Ether(packet_bytes)
                     pkt.sniffed_on = iface
                     parse_packet(pkt, label, capture_metadata=capture_meta)

tools/setup_bridge_capture.sh

@@ -68,6 +68,8 @@ fi
 
 ip link set "$MIRROR_IF" up
 ip link set "$CAPTURE_IF" up
+sysctl -q -w "net.ipv6.conf.$MIRROR_IF.disable_ipv6=1" >/dev/null || true
+sysctl -q -w "net.ipv6.conf.$CAPTURE_IF.disable_ipv6=1" >/dev/null || true
 
 mapfile -t PORTS < <(bridge link show master "$BRIDGE" | awk -F': ' '{print $2}' | awk '{print $1}')
 if [[ ${#PORTS[@]} -eq 0 ]]; then