malmert
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97 lines
3.0 KiB
Bash
Executable File
97 lines
3.0 KiB
Bash
Executable File
#!/usr/bin/env bash
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set -euo pipefail
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usage() {
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cat <<'EOF'
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Usage: tools/setup_bridge_capture.sh --bridge <bridge> [--mirror-if mitmcap0] [--capture-if mitmcap1] [--build-dir /tmp/mitm-bpf]
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Sets up:
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1. A veth pair used as a capture mirror target
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2. tc ingress packet-id marking on each bridge slave
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3. tc mirroring from each bridge slave into the mirror interface
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4. A capture-header injector on the capture-side interface
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Set BACKEND_CAPTURE_INTERFACE to the capture interface printed at the end.
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EOF
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}
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BRIDGE=""
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MIRROR_IF="mitmcap0"
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CAPTURE_IF="mitmcap1"
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BUILD_DIR="/tmp/mitm-bpf"
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while [[ $# -gt 0 ]]; do
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case "$1" in
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--bridge) BRIDGE="$2"; shift 2 ;;
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--mirror-if) MIRROR_IF="$2"; shift 2 ;;
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--capture-if) CAPTURE_IF="$2"; shift 2 ;;
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--build-dir) BUILD_DIR="$2"; shift 2 ;;
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-h|--help) usage; exit 0 ;;
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*) echo "Unknown argument: $1" >&2; usage; exit 1 ;;
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esac
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done
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if [[ -z "$BRIDGE" ]]; then
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usage
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exit 1
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fi
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if ! command -v tc >/dev/null 2>&1 || ! command -v clang >/dev/null 2>&1 || ! command -v ip >/dev/null 2>&1 || ! command -v bridge >/dev/null 2>&1; then
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echo "Missing required tools: tc, clang, ip, and bridge must be installed." >&2
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exit 1
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fi
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if ! ip link show "$BRIDGE" >/dev/null 2>&1; then
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echo "Bridge interface not found: $BRIDGE" >&2
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exit 1
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fi
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mkdir -p "$BUILD_DIR"
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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SRC_DIR="$SCRIPT_DIR/ebpf"
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MARK_OBJ="$BUILD_DIR/mark_packet_id.o"
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CAPTURE_OBJ="$BUILD_DIR/prepend_capture_header.o"
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MULTIARCH_INCLUDE=""
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if command -v gcc >/dev/null 2>&1; then
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GCC_TRIPLE="$(gcc -dumpmachine 2>/dev/null || true)"
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if [[ -n "$GCC_TRIPLE" && -d "/usr/include/$GCC_TRIPLE" ]]; then
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MULTIARCH_INCLUDE="-I/usr/include/$GCC_TRIPLE"
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fi
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fi
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clang -O2 -g -target bpf ${MULTIARCH_INCLUDE:+$MULTIARCH_INCLUDE} -c "$SRC_DIR/mark_packet_id.c" -o "$MARK_OBJ"
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clang -O2 -g -target bpf ${MULTIARCH_INCLUDE:+$MULTIARCH_INCLUDE} -c "$SRC_DIR/prepend_capture_header.c" -o "$CAPTURE_OBJ"
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if ! ip link show "$MIRROR_IF" >/dev/null 2>&1; then
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ip link add "$MIRROR_IF" type veth peer name "$CAPTURE_IF"
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fi
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ip link set "$MIRROR_IF" up
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ip link set "$CAPTURE_IF" up
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mapfile -t PORTS < <(bridge link show master "$BRIDGE" | awk -F': ' '{print $2}' | awk '{print $1}')
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if [[ ${#PORTS[@]} -eq 0 ]]; then
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echo "No bridge slave interfaces found for $BRIDGE" >&2
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exit 1
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fi
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for port in "${PORTS[@]}"; do
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tc qdisc replace dev "$port" clsact
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tc filter replace dev "$port" ingress pref 10 protocol all bpf direct-action obj "$MARK_OBJ" sec classifier
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tc filter replace dev "$port" ingress pref 20 protocol all matchall action mirred egress mirror dev "$MIRROR_IF"
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done
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tc qdisc replace dev "$CAPTURE_IF" clsact
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tc filter replace dev "$CAPTURE_IF" ingress pref 10 protocol all bpf direct-action obj "$CAPTURE_OBJ" sec classifier
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cat <<EOF
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Bridge capture pipeline ready.
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Bridge: $BRIDGE
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Bridge slave ports: ${PORTS[*]}
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Mirror tx interface: $MIRROR_IF
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Capture interface: $CAPTURE_IF
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Set this in backend/.env:
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BACKEND_CAPTURE_INTERFACE=$CAPTURE_IF
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EOF
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