kiss-strip-tcp.sh

#!/bin/bash

# Input & output files
INPUT_PCAP="input.pcapng"
RAW_HEX="raw_hex.txt"
CLEAN_HEX="clean_hex.txt"
FORMATTED_HEX="formatted_hex.txt"
OUTPUT_PCAP="ax25_output.pcapng"

echo "[+] Extracting KISS payload from TCP:8001..."
tshark -r "$INPUT_PCAP" -Y "tcp.port == 8001" -T fields -e tcp.payload > "$RAW_HEX"

echo "[+] Stripping leading/trailing 0xC0 from each frame..."
rm -f "$CLEAN_HEX"
touch "$CLEAN_HEX"
while read -r line; do
    # Remove spaces/newlines
    hex=$(echo "$line" | tr -d '[:space:]')

    # Remove leading and trailing C0 (hex) if present
    hex=$(echo "$hex" | sed -E 's/^(c0)+//; s/(c0)+$//')

    # Skip empty lines
    if [ -n "$hex" ]; then
        echo "$hex" >> "$CLEAN_HEX"
    fi
done < "$RAW_HEX"

echo "[+] Formatting hex dump for text2pcap..."
rm -f "$FORMATTED_HEX"
touch "$FORMATTED_HEX"
while read -r line; do
    # Reset offset for each new packet
    offset=0

    # Insert spaces between hex bytes
    spaced_hex=$(echo "$line" | sed 's/\(..\)/\1 /g')

    # Calculate actual byte count
    byte_count=$(( $(echo "$spaced_hex" | wc -w) ))

    # Print correctly formatted output (each new frame starts at 0000)
    printf "%04x  %s\n" "$offset" "$spaced_hex" >> "$FORMATTED_HEX"

    # Insert a blank line to separate packets
    echo "" >> "$FORMATTED_HEX"

done < "$CLEAN_HEX"

echo "[+] Converting to PCAP with DLT 202 (AX.25 KISS)..."
text2pcap -l 202 "$FORMATTED_HEX" "$OUTPUT_PCAP"

echo "[+] Done! Output saved as: $OUTPUT_PCAP"