Paul Callis
Software Engineer at Georgia Tech Research Institute
Atlanta, Georgia, United States
Summary
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RockstarPaul Callis is a software engineer with a decade of experience specializing in high-performance network and DNS tooling, currently contributing at the Georgia Tech Research Institute in Atlanta. He’s an active back-end contributor to prominent open-source scanning projects ZMap and ZDNS, where he has improved DNS parsing, iterative resolution stability, and CLI features such as nanosecond timestamps. Paul focuses on robustness and efficiency—refactoring core logic, handling malformed responses, and tightening integration with miekg DNS—to make large-scale Internet measurement tools more reliable. His work reflects a blend of research-grade rigor and practical engineering, quietly improving the foundations that power Internet-wide network surveys.
11 years of coding experience
Github Skills (10)
c1710
data-structures10
network-scan10
go10
dns10
c1110
data-structure10
algorithm9
algorithms9
scanner8
Programming languages (8)
Github contributions (5)
zmap/zdns
Aug 2016 - Nov 2022
Fast DNS Lookup Library and CLI Tool
Role in this project:
Back-end Developer
Back-end DeveloperContributions:37 commits, 38 PRs, 65 pushes in 6 years 3 months
Contributions summary:Paul primarily contributed to bug fixes and enhancements for the zdns library. They corrected error messages, improved log file handling, and addressed issues related to DNS resolution, particularly with iterative lookups and the miekg DNS library integration. The user also worked on handling different DNS record types and improved the overall stability and functionality of the DNS lookup tool. Further, they improved the CLI tool by adding new features and options like nanosecond timestamps.
clidns-lookupdnsscanner
zmap/zmap
Sep 2015 - Oct 2017
ZMap is a fast single packet network scanner designed for Internet-wide network surveys.
Role in this project:Back-end Developer
Back-end DeveloperContributions:75 commits, 21 PRs, 73 pushes in 2 years 1 month
Contributions summary:Paul primarily contributed to the development and improvement of the ZMap network scanner, focusing on the DNS module. Their work involved implementing and refactoring the DNS parsing and validation logic, including support for multiple question types, compression handling, and the processing of various resource record (RR) data. They also enhanced the module by adding support for parsing different DNS record types and improving the handling of invalid or malformed DNS responses. Furthermore, the user focused on code quality and efficiency through refactoring the core code and improving the output of the data.
network-scannerinternet-measurementinternet-scanningport-scanner
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