MAC Address (Colon-Separated, Lowercase) Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching mac address (colon-separated, lowercase), ported and verified for Python. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# MAC Address (Colon-Separated, Lowercase)
# ReDoS-safe | RegexVault — Web & Network > MAC Address

import re

mac_address_colonseparated_lowercase_pattern = re.compile(r'^[0-9a-f]{2}(?::[0-9a-f]{2}){5}$')

def validate_mac_address_colonseparated_lowercase(value: str) -> bool:
    return bool(mac_address_colonseparated_lowercase_pattern.fullmatch(value))

# Example
print(validate_mac_address_colonseparated_lowercase("00:1a:2b:3c:4d:5e"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > MAC Address category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Lowercase only. For case-insensitive matching, use net-mac-02. Broadcast MAC is ff:ff:ff:ff:ff:ff. The null/unset MAC is 00:00:00:00:00:00.