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Add PLCP header counting to test_monitor_tshark.sh 

- Add radiotap.present field to capture output
- Count packets with PLCP headers (radiotap information)
- Display PLCP count in both test capture and final summary
- Show warning if no PLCP headers detected (may indicate wrong DLT)

Co-authored-by: Cursor <cursoragent@cursor.com>
This commit is contained in:
Robert McMahon 2026-02-13 13:50:00 -08:00
parent 5827518041
commit a98a255147
1 changed files with 19 additions and 2 deletions
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21
test_monitor_tshark.sh
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@ -80,10 +80,16 @@ iw dev "$INTERFACE" info | grep -E "(type|channel)" || echo "Could not verify"
# Check DLT with tshark (capture for 1 second) # Check DLT with tshark (capture for 1 second)
echo "" echo ""
echo "Checking Data Link Type (1 second test capture)..." echo "Checking Data Link Type (1 second test capture)..."
TEST_OUTPUT=$(timeout 1 tshark -i "$INTERFACE" -T fields -e frame.number 2>&1) TEST_OUTPUT=$(timeout 1 tshark -i "$INTERFACE" -T fields -e frame.number -e radiotap.present 2>&1)
PACKET_COUNT=$(echo "$TEST_OUTPUT" | grep -E '^[0-9]+$' | wc -l || echo "0") PACKET_COUNT=$(echo "$TEST_OUTPUT" | grep -E '^[0-9]+' | wc -l || echo "0")
PLCP_COUNT=$(echo "$TEST_OUTPUT" | grep -E '^[0-9]+.*[0-9]' | wc -l || echo "0")
echo "$TEST_OUTPUT" | tail -5 || true echo "$TEST_OUTPUT" | tail -5 || true
echo "Captured $PACKET_COUNT packet(s) in 1 second" echo "Captured $PACKET_COUNT packet(s) in 1 second"
if [ "$PLCP_COUNT" -gt 0 ]; then
echo "PLCP headers: $PLCP_COUNT (radiotap present)"
else
echo "PLCP headers: 0 (no radiotap headers detected)"
fi
echo "" echo ""
echo "=== Starting tshark capture ($DURATION seconds) ===" echo "=== Starting tshark capture ($DURATION seconds) ==="
@ -99,6 +105,7 @@ CAPTURE_OUTPUT=$(timeout "$DURATION" tshark -i "$INTERFACE" -n -T fields \
-e wlan.fc.type \ -e wlan.fc.type \
-e wlan.fc.subtype \ -e wlan.fc.subtype \
-e wlan.fc.type_subtype \ -e wlan.fc.type_subtype \
-e radiotap.present \
2>&1) 2>&1)
# Display first 50 lines of output # Display first 50 lines of output
@ -107,12 +114,22 @@ echo "$CAPTURE_OUTPUT" | head -50
# Count total packets captured # Count total packets captured
FINAL_COUNT=$(echo "$CAPTURE_OUTPUT" | grep -E '^[0-9]+' | wc -l || echo "0") FINAL_COUNT=$(echo "$CAPTURE_OUTPUT" | grep -E '^[0-9]+' | wc -l || echo "0")
# Count packets with PLCP headers (radiotap present)
# radiotap.present field is the 8th field (after frame.number, frame.time, wlan.sa, wlan.da, wlan.fc.type, wlan.fc.subtype, wlan.fc.type_subtype)
PLCP_COUNT=$(echo "$CAPTURE_OUTPUT" | awk -F'\t' 'NF >= 8 && $8 != "" && $8 != "0" && $8 != "-" {count++} END {print count+0}' || echo "0")
echo "" echo ""
echo "=== Capture complete ===" echo "=== Capture complete ==="
echo "Total packets captured: $FINAL_COUNT" echo "Total packets captured: $FINAL_COUNT"
echo "PLCP headers: $PLCP_COUNT"
echo "" echo ""
if [ "$FINAL_COUNT" -gt 0 ]; then if [ "$FINAL_COUNT" -gt 0 ]; then
echo "✓ Monitor mode is working! Captured $FINAL_COUNT packet(s)" echo "✓ Monitor mode is working! Captured $FINAL_COUNT packet(s)"
if [ "$PLCP_COUNT" -gt 0 ]; then
echo "✓ PLCP headers detected: $PLCP_COUNT packet(s) with radiotap information"
else
echo "⚠ No PLCP headers detected (may be using DLT_IEEE802_11 instead of DLT_IEEE802_11_RADIO)"
fi
else else
echo "✗ No packets captured. Check:" echo "✗ No packets captured. Check:"
echo " 1. Is there WiFi traffic on channel $CHANNEL?" echo " 1. Is there WiFi traffic on channel $CHANNEL?"