pcap to csv pipeline

.gitignore

@@ -1 +1,4 @@
 *.pcap*
+*.gz*
+*.csv*
+*.tsv*

preprocessing/README.md

@@ -6,10 +6,12 @@
     - maybe GRE for VPN usage?
   - L3 - IPv6 is only around 10%, let's drop it
 - Selection (of fields):
-  - Timestamp - note: capture window is from 0500-0515 UTC
+  - Timestamp
+    - capture window is from 0500-0515 UTC
+    - nanosecond precision, use DateTime64 data type in ClickHouse
   - IP
     - addresses - src, dst
-    - protocol - 6 (TCP) or 17 (UDP). cld go for boolean to save space
-  - TCP
+    - protocol - TCP or UDP. cld go for boolean in ClickHouse to save space
+  - TCP/UDP
     - ports - sport, dport
-  - Packet size - in bytes - could exclude L2?
+  - Packet size - in bytes

preprocessing/pcap_processor.py

@@ -0,0 +1,148 @@
+from argparse import ArgumentParser
+from datetime import datetime, timezone
+import csv
+
+from scapy.packet import Packet
+from scapy.utils import PcapReader
+from scapy.layers.inet import IP, TCP, UDP
+
+dbg_print = lambda *x: DEBUG and print(f"[DEBUG] {x}")
+
+
+def pkt_filter(pkt: Packet) -> bool:
+    """filter to include/exclude a packet"""
+    try:
+        assert IP in pkt
+        assert pkt[IP].version == 4
+        assert (TCP in pkt) or (UDP in pkt)
+        return True
+    except AssertionError:
+        return False
+
+
+def pkt_extract(pkt: Packet) -> list:
+    """extract select attributes from a packet"""
+    l4_proto = None
+    if TCP in pkt:
+        l4_proto = TCP
+    elif UDP in pkt:
+        l4_proto = UDP
+    pkt_attrs = [
+        float(pkt.time),
+        pkt.getlayer(l4_proto).name,
+        pkt[IP].src,
+        pkt[IP].dst,
+        pkt[l4_proto].sport,
+        pkt[l4_proto].dport,
+        len(pkt),
+    ]
+
+    pkt_time_str = str(datetime.fromtimestamp(float(pkt.time), timezone.utc))
+    dbg_print(
+        "[{}] {} {}:{} -> {}:{} - {} bytes".format(
+            pkt_time_str,
+            pkt.getlayer(l4_proto).name,
+            pkt[IP].src,
+            pkt[l4_proto].sport,
+            pkt[IP].dst,
+            pkt[l4_proto].dport,
+            len(pkt),
+        )
+    )
+
+    return pkt_attrs
+
+
+def prep_csv(out_file: str):
+    with open(out_file, "w", newline="") as csvfile:
+        writer = csv.writer(csvfile)
+
+        # header row
+        writer.writerow(
+            [
+                "time",
+                "l4_proto",
+                "src_addr",
+                "dst_addr",
+                "src_port",
+                "dst_port",
+                "pkt_len",
+            ]
+        )
+
+
+def pkts_write_csv(pkts: list, out_file: str):
+    with open(out_file, "a", newline="") as csvfile:
+        writer = csv.writer(csvfile)
+        writer.writerows(pkts)
+
+
+if __name__ == "__main__":
+    argp = ArgumentParser()
+    argp.add_argument("-f", "--pcap_file", required=True, dest="_pcap")
+    argp.add_argument("-o", "--out_file", required=False, dest="_out")
+    argp.add_argument(
+        "-x",
+        "--sample",
+        required=False,
+        default=False,
+        dest="_sample",
+        action="store_true",
+    )
+    argp.add_argument(
+        "-s",
+        "--stream",
+        required=False,
+        default=False,
+        dest="_stream",
+        action="store_true",
+    )
+    argp.add_argument(
+        "-d",
+        "--debug",
+        required=False,
+        default=False,
+        dest="_debug",
+        action="store_true",
+    )
+    args = argp.parse_args()
+
+    pcap_file = args._pcap
+    out_file = args._out
+    streaming = args._stream
+    sample = args._sample
+
+    DEBUG = args._debug
+
+    sample_size = 1000000
+    batch_size = 100000
+
+    pcap_rdr = PcapReader(pcap_file)
+    if not streaming:
+        assert args._out and args._out != ""
+        prep_csv(out_file)
+
+    pkts = []
+    for idx, pkt in enumerate(pcap_rdr):
+        # filter packets
+        if not pkt_filter(pkt):
+            continue
+
+        if not streaming:
+            # write to file
+            pkts.append(pkt_extract(pkt))
+
+            if sample and idx > sample_size:
+                break
+
+            if idx > 0 and idx % batch_size == 0:
+                pkts_write_csv(pkts, out_file)
+                pkts = []
+        else:
+            # direct streaming to kafka goes here
+            pass
+    
+    # flush remaining
+    if not streaming and len(pkts) > 0:
+        pkts_write_csv(pkts, out_file)
+