check_interfaces

Deterministic Network Interface Monitoring

check_interfaces is a deterministic network interface monitoring tool designed for operators and monitoring systems that require reproducible, audit‑transparent interface state. It provides canonical filtering, speed enforcement, and structured output suitable for Nagios, Icinga, and automation pipelines.

Frozen Binary Distribution

All NMS_Tools, including check_interfaces, are distributed as standalone frozen executables. They run directly without requiring a Python installation, virtual environment, or external dependencies. This ensures consistent behavior across systems and allows demos and integrations to call the tools exactly as shipped.

Overview

check_interfaces inspects local network interfaces using a deterministic, reproducible pipeline. It supports canonical filtering rules, interface selection, speed validation, and structured metadata extraction. The tool is built around three principles:

1. Determinism — same host → same output
2. Reproducibility — no environment‑dependent behavior
3. Audit Transparency — explicit, structured interface metadata

Key Features

1. Canonical interface filtering (alias, virtual, local, ignore, require)
2. Speed enforcement and validation
3. Deterministic metadata extraction
4. JSON, verbose, and Nagios output modes
5. Operator‑grade error classification
6. Consistent behavior across Linux distributions

Canonical Filtering

• Alias filtering — remove alias interfaces (e.g., eth0:1)
• Virtual filtering — remove virtual interfaces (docker, veth, etc.)
• Local filtering — remove loopback and local‑only interfaces
• Ignore list — explicit operator‑defined exclusions
• Require list — enforce presence of specific interfaces

Deterministic Behavior

• Consistent interface ordering
• Structured metadata for each interface
• Explicit speed validation
• Operator‑grade verbose mode
• Nagios‑compatible single‑line output

Architecture Overview

1. Discovery Layer

Enumerates all network interfaces and retrieves raw metadata from the operating system. All fields are normalized for reproducibility.

2. Filtering Layer

Applies canonical filtering rules to remove irrelevant or non‑operator interfaces. Filtering is deterministic and fully explicit.

3. Validation Layer

• Speed enforcement
• Operational state checks
• Required interface validation

4. Output Layer

Produces deterministic JSON, verbose, or Nagios output. All fields are explicit and audit‑transparent.

Current Status

• Version: 1.0.0
• Edition: Community Edition (public)
• Platform: Linux / Python 3.x
• Dependencies: Standard library only

Roadmap

Near‑Term

• Enhanced speed validation rules
• Interface grouping and tagging
• Improved error classification

Mid‑Term

• Cross‑suite correlation with check_cert.py and check_html.py
• Extended JSON schema
• Interface performance metrics

Long‑Term

• Remote interface inspection
• Distributed interface state aggregation

Why check_interfaces Exists

Traditional interface checkers often produce inconsistent output, rely on distribution‑specific behavior, or provide limited visibility into interface metadata. check_interfaces solves this by applying deterministic engineering principles:

1. explicit filtering
2. reproducible output
3. audit‑transparent reporting
4. no hidden behavior or implicit assumptions

Links

• GitHub Repository
• README (Project Overview)
• Installation Guide
• Usage Guide
• Operation Guide
• Enforcement Model
• Metadata Schema

Related Projects

• NMS Tools Index
• NMS Tools Suite
• Check Certs
• Check HTML
• Check Interfaces
• Check the Weather
• Check Ports
• Check Ticker

License

This check_interfaces is part of the NMS_Tools suite and is released under the MIT License. See the LICENSE file in the repository for full terms.

Contact

If you'd like to reach out, feel free to email me at ldmcclatchey@linktechengineering.net or connect with me on LinkedIn: linkedin.com/in/leonmcclatchey .