# Hidden Treasures - Recycling Large-Scale Internet Measurements to Study the Internet's Control Plane

## TL;DR

This paper demonstrates how large-scale Internet scans can be repurposed to analyze the Internet's control plane by examining ICMP responses, revealing control plane issues like misconfigurations and routing loops.

## Contribution

It introduces a novel secondary analysis of Internet-wide scans to study the control plane, uncovering widespread network problems and routing anomalies.

## Key findings

- Detected outdated and misconfigured routers.
- Uncovered large-scale persistent routing loops in IPv4.
- Analyzed ICMP responses from over 171 million IPs.

## Abstract

Internet-wide scans are a common active measurement approach to study the Internet, e.g., studying security properties or protocol adoption. They involve probing large address ranges (IPv4 or parts of IPv6) for specific ports or protocols. Besides their primary use for probing (e.g., studying protocol adoption), we show that - at the same time - they provide valuable insights into the Internet control plane informed by ICMP responses to these probes - a currently unexplored secondary use. We collect one week of ICMP responses (637.50M messages) to several Internet-wide ZMap scans covering multiple TCP and UDP ports as well as DNS-based scans covering > 50% of the domain name space. This perspective enables us to study the Internet's control plane as a by-product of Internet measurements. We receive ICMP messages from ~171M different IPs in roughly 53K different autonomous systems. Additionally, we uncover multiple control plane problems, e.g., we detect a plethora of outdated and misconfigured routers and uncover the presence of large-scale persistent routing loops in IPv4.