zeek/zeek
Sep 2022 – Jul 2026
17 Months active
Languages Used
C++MarkdownZeekCMakeN/APython
Technical Skills
C++ developmentZeek scriptingdocumentationnetwork programmingnetworkingplugin development
Jan Grashoefer
PROFILE
Jan Grashoefer
Worked extensively on the zeek/zeek repository, delivering 21 features over 17 months focused on network protocol analysis, observability, and backend reliability. Developed enhancements such as reliable packet timestamping, multi-threshold event triggers, and improved logging mechanisms, using C++, Zeek scripting, and Python. Addressed deployment flexibility by overhauling ZeroMQ backend logic and enabling configurable port management for analyzers. Emphasized code maintainability through API simplification, code refactoring, and robust test coverage. Tackled time synchronization challenges and improved shutdown determinism, supporting high-throughput distributed systems. The work demonstrated strong skills in system programming, event-driven design, and network security monitoring across evolving production requirements.
Overall Statistics
Feature vs Bugs
91%Features
Repository Contributions
39Total
Bugs
2
Commits
39
Features
21
Lines of code
2,934
Activity Months17
Your Network
102 peopleSame Organization
@corelight.com22
Shared Repositories
80
Work History
July 2026
4 Commits • 2 Features
Jul 1, 2026July 2026: Delivered foundational enhancements to the Intel framework with improved configurability, observability, and automated validation. Focused on increasing reliability, reducing MTTR, and enabling broader notice generation criteria across deployments.
4 Commits • 2 Features
Jul 1, 2026July 2026: Delivered foundational enhancements to the Intel framework with improved configurability, observability, and automated validation. Focused on increasing reliability, reducing MTTR, and enabling broader notice generation criteria across deployments.
July 2026
June 2026
2 Commits • 1 Features
Jun 1, 2026June 2026 monthly summary for zeek/zeek: Implemented wallclock time fallback and initialization reliability in live clusters to improve time-tracking accuracy and prevent potential year-2038 bugs. Adds baseline tests for network_time_init and wallclock fallback scenarios. This work enhances production stability in live deployments and demonstrates advanced testing and time synchronization capabilities.
June 2026
2 Commits • 1 Features
Jun 1, 2026June 2026 monthly summary for zeek/zeek: Implemented wallclock time fallback and initialization reliability in live clusters to improve time-tracking accuracy and prevent potential year-2038 bugs. Adds baseline tests for network_time_init and wallclock fallback scenarios. This work enhances production stability in live deployments and demonstrates advanced testing and time synchronization capabilities.
May 2026
6 Commits • 2 Features
May 1, 2026May 2026 monthly summary for zeek/zeek: Delivered significant backend and code quality improvements that enhance deployment flexibility, reliability, and maintainability. Key features include ZeroMQ backend overhaul with a separate cluster script and updated supervisor/test deployment workflow, a threading value constructor bug fix to ensure correct data handling across threading operations, and an address utilities refactor to improve namespacing and clarity. These changes reduce deployment complexity, improve runtime stability, and demonstrate strong cross-cutting skills in systems programming, testing, and code organization.
6 Commits • 2 Features
May 1, 2026May 2026 monthly summary for zeek/zeek: Delivered significant backend and code quality improvements that enhance deployment flexibility, reliability, and maintainability. Key features include ZeroMQ backend overhaul with a separate cluster script and updated supervisor/test deployment workflow, a threading value constructor bug fix to ensure correct data handling across threading operations, and an address utilities refactor to improve namespacing and clarity. These changes reduce deployment complexity, improve runtime stability, and demonstrate strong cross-cutting skills in systems programming, testing, and code organization.
May 2026
April 2026
1 Commits • 1 Features
Apr 1, 2026April 2026 monthly summary for zeek/zeek: Delivered SMTP Port 465 support, expanding SMTPS capabilities and ensuring correct handling in the existing port logic. Updated tests to cover the new port, validating output inclusion and regression safety. The focused change is captured in the commit updating btest for the added SMTP port (36e3fa6bcb94290f9df830266f079e8f793db783). Overall, enhanced security posture and compatibility for mail-related features with minimal risk and clear business value.
April 2026
1 Commits • 1 Features
Apr 1, 2026April 2026 monthly summary for zeek/zeek: Delivered SMTP Port 465 support, expanding SMTPS capabilities and ensuring correct handling in the existing port logic. Updated tests to cover the new port, validating output inclusion and regression safety. The focused change is captured in the commit updating btest for the added SMTP port (36e3fa6bcb94290f9df830266f079e8f793db783). Overall, enhanced security posture and compatibility for mail-related features with minimal risk and clear business value.
March 2026
1 Commits • 1 Features
Mar 1, 2026March 2026 (2026-03) monthly summary for zeek/zeek. Key feature delivered: SMTPS port enhancement by adding 465/tcp to the list of well-known SSL ports to improve secure email transmission configuration. No major bugs fixed were reported in this period within the provided data. Overall impact includes better out-of-the-box security configuration, reduced risk of misconfiguration, and maintained alignment with SSL/TLS best practices. Demonstrates solid change management, traceable commits, and domain knowledge of SSL port conventions.
1 Commits • 1 Features
Mar 1, 2026March 2026 (2026-03) monthly summary for zeek/zeek. Key feature delivered: SMTPS port enhancement by adding 465/tcp to the list of well-known SSL ports to improve secure email transmission configuration. No major bugs fixed were reported in this period within the provided data. Overall impact includes better out-of-the-box security configuration, reduced risk of misconfiguration, and maintained alignment with SSL/TLS best practices. Demonstrates solid change management, traceable commits, and domain knowledge of SSL port conventions.
March 2026
December 2025
1 Commits • 1 Features
Dec 1, 2025December 2025 highlights for zeek/zeek: Delivered the Packet Analyzer: Enhanced register_for_ports API, extending the calls with additional parameters to increase flexibility and coverage in packet analyzer tests. Implemented via commit aa47ab8cf39f69dab31edeed19cfc486f5c39217 and included updates to the test harness (btest). No major bugs fixed this month. Overall impact: greater test coverage and more robust packet analysis workflows, enabling faster validation cycles and safer releases. Technologies/skills demonstrated: API design and extension, test infrastructure integration, focused code changes with minimal surface area, and efficient CI alignment.
December 2025
1 Commits • 1 Features
Dec 1, 2025December 2025 highlights for zeek/zeek: Delivered the Packet Analyzer: Enhanced register_for_ports API, extending the calls with additional parameters to increase flexibility and coverage in packet analyzer tests. Implemented via commit aa47ab8cf39f69dab31edeed19cfc486f5c39217 and included updates to the test harness (btest). No major bugs fixed this month. Overall impact: greater test coverage and more robust packet analysis workflows, enabling faster validation cycles and safer releases. Technologies/skills demonstrated: API design and extension, test infrastructure integration, focused code changes with minimal surface area, and efficient CI alignment.
November 2025
2 Commits • 1 Features
Nov 1, 2025Monthly summary for 2025-11: Focused on expanding deployment flexibility in Zeek by enabling configurable port management for built-in analyzers and port-based configuration for packet analyzers. This work supports flexible protocol handling and deployment scenarios, reducing manual reconfiguration during onboarding and runtime adjustments. No major bugs fixed this month as the effort centered on feature delivery and code quality improvements. Technologies demonstrated include the Zeek network analysis framework, configuration-driven design, and commit-driven development with attention to maintainability and testability.
2 Commits • 1 Features
Nov 1, 2025Monthly summary for 2025-11: Focused on expanding deployment flexibility in Zeek by enabling configurable port management for built-in analyzers and port-based configuration for packet analyzers. This work supports flexible protocol handling and deployment scenarios, reducing manual reconfiguration during onboarding and runtime adjustments. No major bugs fixed this month as the effort centered on feature delivery and code quality improvements. Technologies demonstrated include the Zeek network analysis framework, configuration-driven design, and commit-driven development with attention to maintainability and testability.
November 2025
October 2025
2 Commits • 1 Features
Oct 1, 2025October 2025: Delivered a strategic enhancement to the Zeek logging subsystem, introducing Global Flush and Broker-Buffer Aware Flushing to improve reliability and observability in distributed deployments. Added Log::flush_all to flush all log streams and writers, and standardized internal naming by renaming FlushAllWriteBuffers to FlushAll for consistency. Enhanced cluster behavior by ensuring broker buffers are flushed when running as a cluster backend, invoking FlushLogBuffers on the broker manager to prevent potential data loss during high throughput or failover scenarios. The changes strengthen data integrity across nodes and simplify maintenance with a unified API surface.
October 2025
2 Commits • 1 Features
Oct 1, 2025October 2025: Delivered a strategic enhancement to the Zeek logging subsystem, introducing Global Flush and Broker-Buffer Aware Flushing to improve reliability and observability in distributed deployments. Added Log::flush_all to flush all log streams and writers, and standardized internal naming by renaming FlushAllWriteBuffers to FlushAll for consistency. Enhanced cluster behavior by ensuring broker buffers are flushed when running as a cluster backend, invoking FlushLogBuffers on the broker manager to prevent potential data loss during high throughput or failover scenarios. The changes strengthen data integrity across nodes and simplify maintenance with a unified API surface.
July 2025
3 Commits • 1 Features
Jul 1, 2025July 2025 monthly summary for zeek/zeek: Delivered multi-threshold support for generic packet thresholds and the new conn_generic_packet_threshold_crossed event, boosting observability and granularity of threshold-based triggers. Updated test baseline to reflect threshold-driven behavior and added release notes documenting the feature. These changes enable finer-grained monitoring and proactive alerting with minimal performance impact. No major customer-reported bugs fixed this month; primary focus was feature delivery, test stabilization, and documentation.
3 Commits • 1 Features
Jul 1, 2025July 2025 monthly summary for zeek/zeek: Delivered multi-threshold support for generic packet thresholds and the new conn_generic_packet_threshold_crossed event, boosting observability and granularity of threshold-based triggers. Updated test baseline to reflect threshold-driven behavior and added release notes documenting the feature. These changes enable finer-grained monitoring and proactive alerting with minimal performance impact. No major customer-reported bugs fixed this month; primary focus was feature delivery, test stabilization, and documentation.
July 2025
June 2025
2 Commits • 1 Features
Jun 1, 2025June 2025: Delivered a new event Conn Generic Packet Threshold Crossed in zeek/zeek to signal when a connection reaches a configurable packet threshold. This adds a targeted monitoring signal as an alternative to the new_connection event for specific scenarios, backed by baseline tests to verify correct logging. No major bugs fixed this month; the focus was on feature delivery and test coverage to improve observability and reliability.
June 2025
2 Commits • 1 Features
Jun 1, 2025June 2025: Delivered a new event Conn Generic Packet Threshold Crossed in zeek/zeek to signal when a connection reaches a configurable packet threshold. This adds a targeted monitoring signal as an alternative to the new_connection event for specific scenarios, backed by baseline tests to verify correct logging. No major bugs fixed this month; the focus was on feature delivery and test coverage to improve observability and reliability.
May 2025
1 Commits • 1 Features
May 1, 2025May 2025 monthly summary for zeek/zeek. Focused on delivering a robust POP3 analysis capability with improved STARTTLS visibility in POP3 sessions. Key features delivered include adding STLS support to the POP3 protocol analysis (DPD signature) and updating client-side payload detection to include STLS for accurate STARTTLS negotiation identification, plus simplifying loading of the POP3 protocol analyzer in the test script. No major bugs reported this month.
1 Commits • 1 Features
May 1, 2025May 2025 monthly summary for zeek/zeek. Focused on delivering a robust POP3 analysis capability with improved STARTTLS visibility in POP3 sessions. Key features delivered include adding STLS support to the POP3 protocol analysis (DPD signature) and updating client-side payload detection to include STLS for accurate STARTTLS negotiation identification, plus simplifying loading of the POP3 protocol analyzer in the test script. No major bugs reported this month.
May 2025
April 2025
4 Commits • 1 Features
Apr 1, 2025April 2025 monthly summary for zeek/zeek focusing on shutdown reliability improvements, API simplification, and stability fixes. Delivered deterministic shutdown behavior, reduced risk of edge-case failures during maintenance windows, and demonstrated strong API hygiene and maintainability.
April 2025
4 Commits • 1 Features
Apr 1, 2025April 2025 monthly summary for zeek/zeek focusing on shutdown reliability improvements, API simplification, and stability fixes. Delivered deterministic shutdown behavior, reduced risk of edge-case failures during maintenance windows, and demonstrated strong API hygiene and maintainability.
December 2024
3 Commits • 2 Features
Dec 1, 2024December 2024 monthly summary for zeek/zeek focusing on observability improvements and policy-enforcement readiness. Delivered two core features that enhance packet processing visibility and policy hooks, with accompanying test coverage to ensure reliability and faster troubleshooting.
3 Commits • 2 Features
Dec 1, 2024December 2024 monthly summary for zeek/zeek focusing on observability improvements and policy-enforcement readiness. Delivered two core features that enhance packet processing visibility and policy hooks, with accompanying test coverage to ensure reliability and faster troubleshooting.
December 2024
August 2024
2 Commits • 1 Features
Aug 1, 2024August 2024 — zeek/zeek: Key feature delivered: Reliable Packet Timestamping when Network Time is Unavailable. Implemented get_current_packet_ts to capture the timestamp of the currently processed packet when network time is unavailable, with baseline tests to verify accuracy relative to network time events. This reduces packet lag during time-sync outages and improves observability for offline analysis and incident investigation. Major gains: Improved packet timeline accuracy, better offline debugging capabilities, and stronger resilience to time-sync outages in time-critical analytics. Overall impact and accomplishments: Strengthened core timing reliability for high-precision network monitoring, enabling more consistent traceability and faster incident response in degraded time environments. Demonstrated end-to-end feature development from code change to testing in a critical repository. Technologies/skills demonstrated: feature design, test-driven development (baseline tests), time synchronization handling, code quality and maintainability, and repo-wide contribution in zeek/zeek.
August 2024
2 Commits • 1 Features
Aug 1, 2024August 2024 — zeek/zeek: Key feature delivered: Reliable Packet Timestamping when Network Time is Unavailable. Implemented get_current_packet_ts to capture the timestamp of the currently processed packet when network time is unavailable, with baseline tests to verify accuracy relative to network time events. This reduces packet lag during time-sync outages and improves observability for offline analysis and incident investigation. Major gains: Improved packet timeline accuracy, better offline debugging capabilities, and stronger resilience to time-sync outages in time-critical analytics. Overall impact and accomplishments: Strengthened core timing reliability for high-precision network monitoring, enabling more consistent traceability and faster incident response in degraded time environments. Demonstrated end-to-end feature development from code change to testing in a critical repository. Technologies/skills demonstrated: feature design, test-driven development (baseline tests), time synchronization handling, code quality and maintainability, and repo-wide contribution in zeek/zeek.
July 2023
1 Commits • 1 Features
Jul 1, 2023July 2023 monthly summary focusing on business value and technical achievements. Key feature delivered: Documentation: Built-in AF_Packet plugin in Zeek 5.2. Updated documentation informs users that Zeek ships with a built-in AF_Packet plugin starting from version 5.2, improving awareness and reducing installation confusion. Notable commit reference included to support traceability: a4cd5dd452894ce9f20d561e2c3a34edd5027933 (af_packet: Note that Zeek ships with a built-in version).
1 Commits • 1 Features
Jul 1, 2023July 2023 monthly summary focusing on business value and technical achievements. Key feature delivered: Documentation: Built-in AF_Packet plugin in Zeek 5.2. Updated documentation informs users that Zeek ships with a built-in AF_Packet plugin starting from version 5.2, improving awareness and reducing installation confusion. Notable commit reference included to support traceability: a4cd5dd452894ce9f20d561e2c3a34edd5027933 (af_packet: Note that Zeek ships with a built-in version).
July 2023
October 2022
2 Commits • 2 Features
Oct 1, 20222022-10 monthly performance summary for zeek/zeek focused on feature delivery and release readiness of kernel/network capabilities. Key features delivered: (1) Kernel checksum offload capability diagnostic: adds a runtime check for the TP_STATUS_CSUM_VALID symbol in the kernel headers and emits a warning if it is not defined, surfacing potential limitations in checksum offloading support. (2) AF_Packet plugin 4.0.0 release: upgrades AF_Packet plugin version from 3.2.0 to 4.0.0, signaling a release with potential enhancements or fixes. No major bugs fixed this month; efforts concentrated on feature delivery, observability, and release readiness. Overall impact: improved visibility into checksum offload compatibility and a smoother upgrade path for users relying on AF_Packet, supporting more reliable high-throughput packet processing. Technologies/skills demonstrated: kernel header awareness, runtime diagnostics, versioned plugin releases, and change traceability with clear commit references (61a3538106010a7ac5e1ce7f0734ae20773da653; 165d60236c875501815f05018b852207b06d08e8).
October 2022
2 Commits • 2 Features
Oct 1, 20222022-10 monthly performance summary for zeek/zeek focused on feature delivery and release readiness of kernel/network capabilities. Key features delivered: (1) Kernel checksum offload capability diagnostic: adds a runtime check for the TP_STATUS_CSUM_VALID symbol in the kernel headers and emits a warning if it is not defined, surfacing potential limitations in checksum offloading support. (2) AF_Packet plugin 4.0.0 release: upgrades AF_Packet plugin version from 3.2.0 to 4.0.0, signaling a release with potential enhancements or fixes. No major bugs fixed this month; efforts concentrated on feature delivery, observability, and release readiness. Overall impact: improved visibility into checksum offload compatibility and a smoother upgrade path for users relying on AF_Packet, supporting more reliable high-throughput packet processing. Technologies/skills demonstrated: kernel header awareness, runtime diagnostics, versioned plugin releases, and change traceability with clear commit references (61a3538106010a7ac5e1ce7f0734ae20773da653; 165d60236c875501815f05018b852207b06d08e8).
September 2022
2 Commits • 1 Features
Sep 1, 20222022-09 monthly summary for zeek/zeek focusing on AF_Packet checksum validation improvements and documentation. Delivered clearer checksum validation mode, removed the previous offloading mode, and updated documentation to reflect usage, permissions, offloading options, configuration, and limitations. This work enhances reliability, maintainability, and developer onboarding; reduced ambiguity in AF_Packet behavior across configurations. No major bugs fixed this month.
2 Commits • 1 Features
Sep 1, 20222022-09 monthly summary for zeek/zeek focusing on AF_Packet checksum validation improvements and documentation. Delivered clearer checksum validation mode, removed the previous offloading mode, and updated documentation to reflect usage, permissions, offloading options, configuration, and limitations. This work enhances reliability, maintainability, and developer onboarding; reduced ambiguity in AF_Packet behavior across configurations. No major bugs fixed this month.
September 2022
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Quality Metrics
Correctness95.2%
Maintainability91.6%
Architecture92.0%
Performance89.2%
AI Usage20.6%
Skills & Technologies
Programming Languages
C++CMakeMarkdownN/APythonZeek
Technical Skills
C++C++ developmentC++ programmingCMakeCode RefactoringData StructuresDeprecationDistributed SystemsDocumentationEvent HandlingKernel DevelopmentLog AnalysisLoggingMemory ManagementNetwork Analysis
Repositories Contributed To
Overview of all repositories you've contributed to across your timeline