NetworkInspector.CLI 0.6.0

NetworkInspector.CLI

Command-line entry point for capture conversion and packet export workflows. The executable name is ni.

What This Is

NetworkInspector.CLI provides two production-oriented commands:

• ni convert for frame-level format conversion (PCAP/PCAPNG/BLF/ASC workflows).
• ni export for protocol parsing and packet-level export (JSON/PBF/Text/Parquet/DuckDB workflows).

Application logic lives in the NetworkInspector.CLI.Core class library (tested and gated by ExitPointGaps). The ni executable is a thin host that forwards to CliEntry.Run.

Why It Stands Out

• One CLI for both format conversion and parsed packet export.
• File-based workflows with optional size/count splitting for large captures.
• Tolerant mode and progress reporting for large or imperfect captures.
• Stable exit-code contract for scripts and CI jobs.

Install

Global tool install:

dotnet tool install -g NetworkInspector.CLI

Local tool install (repository or project scope):

dotnet new tool-manifest
dotnet tool install NetworkInspector.CLI

Then run:

ni --help

Quick Start

Convert a BLF capture to PCAPNG:

ni convert capture.blf --output capture.pcapng

Export packets as compact JSON to a file:

ni export capture.pcapng --format json --output capture.json

Export text output to a file:

ni export capture.pcapng --format text --output capture.txt

Commands

Run ni <command> --help for full command help.

ni convert

Frame-level conversion. No packet parsing is performed.

ni convert <input> [<input2> ...] --output <path> [options]

Common options:

• --output, -o Output file path (required).
• --output-format, --format, -f Explicit output format spec (overrides extension).
• --profile <name> Settings profile (available to sources and exporters).
• --settings-path <dir> Base directory for settings storage.
• --max-frames, -n Maximum number of frames to process.
• --split-size <MB> Split output at this size in MiB.
• --split-count <N> Split output every N frames.
• --filter <expr> Only keep frames whose packet matches the expression.
• --blf-cache-size <MB> BLF cache budget in MiB.
• --progress <N> Report progress every N frames (stderr).
• --tolerant Skip malformed frames instead of aborting.

Conversion is frame-level by default: no protocol stack is built and no frame is parsed. Passing a non-empty --filter changes that, because each frame has to be parsed before it can be judged. An omitted, empty, or whitespace-only --filter keeps the fast frame-copy path.

Format variants:

Examples:

# Convert BLF to PCAPNG
ni convert capture.blf --output capture.pcapng

# Split a large file into 100 MiB chunks (base name + numbered suffix)
ni convert big.pcapng --output split/part.pcapng --split-size 100

# Convert multiple sources into one output
ni convert a.blf b.blf --output merged.pcapng

# Keep only DNS traffic (parses frames, unlike the plain conversion above)
ni convert capture.pcapng --output dns.pcapng --filter "udp.dstport == 53"

ni export

Parse frames through the protocol stack and export one record per packet.

ni export <input> [<input2> ...] --output <path> [--format <fmt>] [options]

Common options:

• --output, -o Output file path (required).
• --format, -f Export format spec.
• --max-packets, -n Maximum packets to export.
• --split-size <MB> Split when live EstimatedOutputBytes reaches this size (MiB; no filesystem probe).
• --split-count <N> Split output every N packets (numbered files, or sibling Parquet directories).
• --filter <expr> Only export packets matching the expression.
• --profile <name> Settings profile name.
• --settings-path <dir> Base directory for settings storage.
• --blf-cache-size <MB> BLF cache budget in MiB.
• --progress <N> Report progress every N packets (stderr).
• --tolerant Skip malformed frames instead of aborting.

If --format is omitted, format is chosen from --output extension when possible.

Format variants:

For PBF, compression is enabled by default unless nocompress is specified.

Examples:

# Compact JSON to file
ni export capture.pcapng --format json --output capture.json

# Pretty JSON to file
ni export capture.pcapng --format json:style=pretty --output capture.json

# Human-readable protocol tree
ni export capture.pcapng --format text --output capture.txt

# Columnar PBF with compression
ni export capture.pcapng --format pbf:format=columnar,compressed --output capture.pbf

# Split export every 10_000 packets
ni export capture.pcapng --format json --output split/part.json --split-count 10000

# Parquet dataset directory
ni export capture.pcapng --format parquet --output out_parquet

# Split Parquet into sibling dataset directories every 50_000 packets
ni export capture.pcapng --format parquet --output out_parquet --split-count 50000

# DuckDB file (also supports --split-count / --split-size)
ni export capture.pcapng --format duckdb --output out.duckdb

# Tolerant export with progress checkpoints
ni export unknown-input.blf --format text --output output.txt --tolerant --progress 50000

# Only HTTPS packets
ni export capture.pcapng --format json --output tls.json --filter "tcp.port == 443"

Filtering

Both commands accept the same expression language, documented in FILTER_GUIDE.md.

Behavior shared by convert and export:

• A packet is judged before any output is opened, so a filter that matches nothing writes no file and no dataset directory at all.
• An expression that does not compile exits with the usage/validation code (1) and names the position of the problem on stderr.
• An expression that fails to evaluate aborts with the runtime code (3) rather than writing a partially filtered output.
• --max-frames / --max-packets count what is written, so they cap matching records.

Exit Codes

Safe Usage (STRIDE)

• Spoofing: Prefer captures from trusted, attributable sources.
• Tampering: Use --tolerant for unknown files and inspect warnings.
• Repudiation: Keep original inputs and outputs together for reproducibility.
• Information disclosure: Treat JSON/Text outputs as sensitive when payload data may contain secrets.
• Denial of service: Use --max-frames, --max-packets, split options, progress checkpoints, and cancellation.
• Elevation of privilege: Run ni with least required file-system and process permissions.

Operational Notes

• Output uses UTF-8 console encoding.
• Progress and diagnostics go to stderr.
• Ctrl+C triggers cooperative cancellation for long-running operations.
• Output path (-o / --output) is always required; stdout (-) is not supported.

Links

• GitHub repository
• NuGet package
• Source folder
• Root overview
• Issue tracker

License

MIT License