Working with massive packet capture files (especially those over 1GB) can make Wireshark unresponsive or crash completely. This happens because:

• Wireshark loads the entire file into memory for analysis
• Modern networks generate enormous amounts of traffic data
• Long-running captures accumulate too many packets

While split command might seem tempting, it corrupts the PCAP format. Instead, use these proper methods:

Method 1: Using editcap (Wireshark's Built-in Tool)

# Split by packet count (creates 1000-packet chunks)
editcap -c 1000 largefile.pcap split_file_.pcap

# Split by file size (100MB chunks)
editcap -C 100000000 largefile.pcap split_file_.pcap

# Split by time duration (5-minute intervals)
editcap -i 300 largefile.pcap split_file_.pcap

Method 2: Using tshark (Alternative Approach)

# Export every 10,000 packets to separate files
tshark -r largefile.pcap -C 10000 -w split_file.pcap

Method 3: Using tcpslice for Time-Based Splitting

# Extract packets between specific timestamps
tcpslice -w output.pcap +2018-07-01.15:30:00 largefile.pcap

For complex requirements, combine filters with splitting:

# Split HTTP traffic by host while preserving original timestamps
editcap -F pcap -i 3600 -A "http.host contains 'example.com'" \
input.pcap http_traffic_.pcap

• Process large files on machines with sufficient RAM
• Consider using SSDs for faster I/O operations
• For multi-core systems, parallel processing may help:

  parallel -j 4 editcap -c 25000 big.pcap split{}_.pcap ::: {1..4}

Always validate your output files:

capinfos split_file_*.pcap
tshark -r split_file_00001.pcap -c 1

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Working with massive packet capture files (PCAP) can be frustrating when tools like Wireshark become unresponsive. This often happens when dealing with multi-gigabyte captures from long-running tcpdump sessions or high-traffic network environments.

Common solutions like using tcpdump filters or Linux's split command often don't work because:

• Host/port filters can't separate traffic when both ends are unknown
• Binary splitting corrupts the PCAP format
• Wireshark expects valid PCAP headers in each file

Wireshark's built-in editcap utility provides the perfect solution:

editcap -c <packets_per_file> input.pcap output_prefix.pcap

Example splitting every 10,000 packets:

editcap -c 10000 large_capture.pcap split_capture_

This creates files like split_capture_00001.pcap, split_capture_00002.pcap, etc.

When you need time-based segmentation instead of packet counts:

tshark -r input.pcap -b filesize:100000 -w output.pcap

This creates 100MB chunks (-b filesize in KB). Other -b options include:

• filesize: Split by file size
• interval: Split by time interval
• packets: Split by packet count

For terabyte-scale PCAPs, combine with dumpcap for memory efficiency:

dumpcap -r huge.pcap -b filesize:1000000 -w chunk.pcap

Always validate the output files with:

capinfos split_capture_00001.pcap

Check that:

• Packet counts match your expectations
• Timestamps are continuous between files
• No packets were corrupted during splitting

For regular processing, create a bash script:

#!/bin/bash
INPUT=$1
PACKETS_PER_FILE=50000
OUTPUT_PREFIX="split_${INPUT%.*}"

editcap -c $PACKETS_PER_FILE "$INPUT" "$OUTPUT_PREFIX.pcap"