# jagt/clumsy

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6,110 stars · 613 forks · C · NOASSERTION

## Links

- GitHub: https://github.com/jagt/clumsy
- Homepage: http://jagt.github.io/clumsy/
- awesome-repositories: https://awesome-repositories.com/repository/jagt-clumsy.md

## Description

Clumsy is a Windows network fault injection tool that intercepts system-wide network traffic at the kernel level using the WinDivert driver, without requiring proxy configuration or application code changes. It captures and manipulates packets for all running applications, including localhost connections, enabling controlled testing of application behavior under degraded network conditions.

The tool provides comprehensive network impairment capabilities including latency simulation, bandwidth throttling, packet loss, corruption, duplication, and reordering. Users can apply these impairments selectively by packet direction (inbound, outbound, or loopback) and filter traffic using logical expressions based on protocol, port, or IP address. Real-time interactive controls allow starting and stopping packet manipulation on demand with live visual feedback while applications continue running.

Clumsy supports randomized packet mutation that can simultaneously drop, duplicate, or corrupt a configurable percentage of packets to emulate network degradation. An in-memory packet buffer holds intercepted packets to introduce latency, reorder traffic, or throttle throughput before forwarding. The tool is available as a Windows executable that can be run without installation.

## Tags

### DevOps & Infrastructure

- [Windows Network Fault Injection Tools](https://awesome-repositories.com/f/devops-infrastructure/fault-tolerance/kernel-fault-injection/fault-injection-testing/network-faults/windows-network-fault-injection-tools.md) — Intercepts system-wide network traffic on Windows to simulate latency, packet loss, corruption, duplication, and reordering for testing application resilience.
- [Network Faults](https://awesome-repositories.com/f/devops-infrastructure/fault-tolerance/kernel-fault-injection/fault-injection-testing/network-faults.md) — Intercepts system-wide network traffic to simulate latency, loss, corruption, and reordering for testing.

### Networking & Communication

- [WinDivert](https://awesome-repositories.com/f/networking-communication/packet-capture-drivers/windivert.md) — Intercepts network packets at the Windows kernel layer using the WinDivert driver for system-wide manipulation.
- [Bandwidth Management](https://awesome-repositories.com/f/networking-communication/bandwidth-management.md) — Limits packet transmission rates to simulate constrained bandwidth for application testing. ([source](https://cdn.jsdelivr.net/gh/jagt/clumsy@master/README.md))
- [Bandwidth Throttling Simulators](https://awesome-repositories.com/f/networking-communication/bandwidth-management/bandwidth-throttling-simulators.md) — Limits packet transmission rates to simulate constrained bandwidth for application testing.
- [Packet Capture Drivers](https://awesome-repositories.com/f/networking-communication/packet-capture-drivers.md) — Intercepts network packets at the kernel level using the WinDivert driver for system-wide manipulation.
- [WinDivert](https://awesome-repositories.com/f/networking-communication/packet-capture-engines/windivert.md) — Captures and modifies network packets at the Windows kernel layer using the WinDivert driver.
- [Packet Capture Filters](https://awesome-repositories.com/f/networking-communication/packet-capture-filters.md) — Captures only packets matching user-defined rules based on direction, protocol, port, or IP address. ([source](http://jagt.github.io/clumsy))
- [Packet Property Filters](https://awesome-repositories.com/f/networking-communication/packet-capture-filters/packet-property-filters.md) — Intercepts and filters packets using boolean logic on fields like protocol, port, and direction to target specific traffic for manipulation. ([source](http://jagt.github.io/clumsy/manual.html))
- [Packet Dropping](https://awesome-repositories.com/f/networking-communication/packet-dropping.md) — Randomly drops, duplicates, or corrupts a configurable percentage of packets to simulate network degradation. ([source](http://jagt.github.io/clumsy/manual.html))
- [Packet Content Tampering](https://awesome-repositories.com/f/networking-communication/packet-engines/packet-construction/malformed-packet-generation/packet-content-tampering.md) — Modifies packet data in transit to test how applications handle corrupted or malformed network traffic. ([source](http://jagt.github.io/clumsy))
- [Real-time Packet Modification](https://awesome-repositories.com/f/networking-communication/packet-engines/packet-construction/real-time-packet-modification.md) — Starts and stops packet manipulation on demand with live visual feedback while applications continue running.
- [Real-Time Network Impairment Controls](https://awesome-repositories.com/f/networking-communication/packet-engines/packet-construction/real-time-packet-modification/real-time-network-impairment-controls.md) — Starts and stops packet manipulation on demand while applications keep running, with real-time visual feedback. ([source](https://cdn.jsdelivr.net/gh/jagt/clumsy@master/README.md))
- [Real-Time Traffic Filters](https://awesome-repositories.com/f/networking-communication/packet-engines/packet-construction/real-time-packet-modification/real-time-traffic-filters.md) — Starts and stops packet filtering interactively with visual feedback, targeting specific protocols, ports, or directions.
- [Packet Content Tampering](https://awesome-repositories.com/f/networking-communication/packet-engines/packet-redirection/packet-content-tampering.md) — Modifies or corrupts packet data in transit to test application resilience to data corruption. ([source](http://jagt.github.io/clumsy/manual.html))
- [Packet Manipulation Toolkits](https://awesome-repositories.com/f/networking-communication/packet-manipulation-toolkits.md) — Intercepts and modifies network packets system-wide to evaluate protocol and application behavior under adverse conditions.
- [Packet Duplication](https://awesome-repositories.com/f/networking-communication/packet-manipulation-toolkits/packet-duplication.md) — Modifies packet data in transit to simulate corruption or manipulation, helping test error handling in applications. ([source](https://cdn.jsdelivr.net/gh/jagt/clumsy@master/README.md))
- [Packet Content Tampering](https://awesome-repositories.com/f/networking-communication/packet-manipulation-toolkits/packet-duplication/packet-content-tampering.md) — Modifies packet data in transit, enabling tests of application resilience against corrupted or manipulated network traffic. ([source](http://jagt.github.io/clumsy/cn/index.html))
- [Packet Mutation Engines](https://awesome-repositories.com/f/networking-communication/packet-manipulation-toolkits/packet-mutation-engines.md) — Modifies, drops, duplicates, or reorders packets in transit to emulate real-world network failure conditions.
- [Packet Reordering Buffers](https://awesome-repositories.com/f/networking-communication/packet-reordering-buffers.md) — Rearranges the order of captured packets before forwarding them, simulating out-of-order delivery. ([source](http://jagt.github.io/clumsy))
- [Packet Reordering Simulators](https://awesome-repositories.com/f/networking-communication/packet-reordering-buffers/packet-reordering-simulators.md) — Alters the sequence in which packets are sent to test application resilience to out-of-order delivery. ([source](http://jagt.github.io/clumsy/cn/index.html))
- [Scriptable Packet Filters](https://awesome-repositories.com/f/networking-communication/scriptable-packet-filters.md) — Uses a logical expression to match packets based on fields like TCP, UDP, ICMP, inbound, or outbound, targeting only the traffic of interest. ([source](http://jagt.github.io/clumsy/manual.html))
- [Directional](https://awesome-repositories.com/f/networking-communication/traffic-filters/directional.md) — Applies network impairments independently to inbound or outbound traffic using WinDivert filter expressions for targeted testing.
- [Port-Based Filters](https://awesome-repositories.com/f/networking-communication/traffic-filters/port-based-filters.md) — Intercepts only packets matching user-defined criteria such as TCP/UDP protocol, port numbers, or logical expressions. ([source](http://jagt.github.io/clumsy/cn/index.html))
- [Traffic Interception](https://awesome-repositories.com/f/networking-communication/traffic-interception.md) — Captures and modifies system-wide network traffic without requiring proxy setup or application code changes. ([source](https://cdn.jsdelivr.net/gh/jagt/clumsy@master/README.md))
- [Packet Buffering](https://awesome-repositories.com/f/networking-communication/packet-buffering.md) — Holds intercepted packets in a configurable buffer to introduce latency, reorder, or throttle traffic.
- [Directional Packet Filters](https://awesome-repositories.com/f/networking-communication/packet-capture-filters/interface-level-packet-filtering/directional-packet-filters.md) — Applies network impairments independently to inbound or outbound traffic for targeted testing. ([source](http://jagt.github.io/clumsy/manual.html))
- [Packet Tampering Tools](https://awesome-repositories.com/f/networking-communication/packet-engines/packet-construction/malformed-packet-generation/packet-tampering-tools.md) — Modifies packet content or headers on the fly to test application resilience against corrupted or malformed data. ([source](https://cdn.jsdelivr.net/gh/jagt/clumsy@master/README.md))
- [Packet Corruption Tools](https://awesome-repositories.com/f/networking-communication/packet-engines/packet-construction/packet-corruption-tools.md) — Modifies packet data in transit to simulate tampering or bit errors, enabling robustness testing of network protocols. ([source](http://jagt.github.io/clumsy/manual.html))
- [Traffic Filters](https://awesome-repositories.com/f/networking-communication/traffic-filters.md) — Independently applies impairments to inbound or outbound traffic by filtering packet direction in the capture layer.

### Part of an Awesome List

- [Connectivity Degradation Simulators](https://awesome-repositories.com/f/awesome-lists/devtools/network-simulation-tools/connectivity-degradation-simulators.md) — Intercepts network packets to introduce controlled lag, loss, and tampering for testing. ([source](http://jagt.github.io/clumsy/whoisusingclumsy.html))

### Business & Productivity Software

- [Direction Filters](https://awesome-repositories.com/f/business-productivity-software/tag-filtering-systems/message-filtering/direction-filters.md) — Applies network conditions selectively to inbound, outbound, or loopback traffic. ([source](http://jagt.github.io/clumsy/manual.html))

### Graphics & Multimedia

- [Real-time Filter Management](https://awesome-repositories.com/f/graphics-multimedia/audio-music/audio-processing/real-time-audio-threading/real-time-filter-management.md) — Starts and stops packet manipulation on demand without restarting applications, using dynamic filter activation.
- [Packet Filter Expressions](https://awesome-repositories.com/f/graphics-multimedia/dynamic-filter-expressions/packet-filter-expressions.md) — Applies user-defined logical expressions based on protocol, port, IP, and direction to selectively capture and modify packets.

### Operating Systems & Systems Programming

- [Kernel-Level Traffic Interceptors](https://awesome-repositories.com/f/operating-systems-systems-programming/kernel-core-internals/operating-system-kernels/kernel-mode-interception-mechanisms/kernel-level-traffic-interceptors.md) — Intercepts network packets at the Windows kernel layer using the WinDivert driver for system-wide manipulation.

### Security & Cryptography

- [Packet Filtering Engines](https://awesome-repositories.com/f/security-cryptography/packet-filtering-engines.md) — Selects which packets to affect based on protocol (TCP, UDP, ICMP) and direction (inbound, outbound) using a logical expression. ([source](http://jagt.github.io/clumsy/manual.html))

### System Administration & Monitoring

- [System-Wide Interception Modes](https://awesome-repositories.com/f/system-administration-monitoring/administrative-operations/linux-system-administration/networking/proxy-management-systems/traffic-routing-controllers/traffic-routing-modes/system-wide-interception-modes.md) — Intercepts all network traffic on the system without requiring proxy setup or application changes. ([source](https://cdn.jsdelivr.net/gh/jagt/clumsy@master/README.md))

### Testing & Quality Assurance

- [Network Latency Simulators](https://awesome-repositories.com/f/testing-quality-assurance/api-network-testing/network-latency-simulators.md) — Delays outgoing and incoming packets to mimic high-lag network conditions for testing. ([source](http://jagt.github.io/clumsy/manual.html))
- [Packet Loss Simulators](https://awesome-repositories.com/f/testing-quality-assurance/api-network-testing/network-latency-simulators/packet-loss-simulators.md) — Randomly drops, duplicates, or corrupts a configurable percentage of packets to simulate network degradation and test error handling. ([source](https://cdn.jsdelivr.net/gh/jagt/clumsy@master/README.md))
- [Randomized Packet Mutation Simulators](https://awesome-repositories.com/f/testing-quality-assurance/api-network-testing/network-latency-simulators/packet-loss-simulators/randomized-packet-mutation-simulators.md) — Randomly drops, duplicates, or corrupts a configurable percentage of packets to emulate network degradation.
- [Windows Network Degradation Simulators](https://awesome-repositories.com/f/testing-quality-assurance/api-network-testing/network-latency-simulators/windows-network-degradation-simulators.md) — Applies controlled network degradation on Windows without proxy configuration or code changes.

### Development Tools & Productivity

- [Burst Traffic Simulators](https://awesome-repositories.com/f/development-tools-productivity/execution-throttling/network-throttling/burst-traffic-simulators.md) — Blocks traffic then releases queued packets to emulate bursty or congested network links. ([source](http://jagt.github.io/clumsy/cn/index.html))