NeckSim Pro

NeckSim Pro is a proxy that facilitates Network Condition Simulation. This tool sits between a client and a target server to intentionally introduce issues like latency and packet loss to the traffic passing through it. 

Usage: necksimpro <configuration_file> 

NeckSim Pro: the ultimate man in the middle, or indeed the neckbeard in the middle, proxy for stressing your networks with!

Features:

• Latency and Jitter Simulation
  Introduces mean latency with normally distributed jitter for realistic timing variance.

• Packet Loss Emulation
  Drops packets randomly based on a configurable percentage in order to test network resilience.

• Bandwidth Limiting
  Restricts outgoing throughput using a token-bucket–like algorithm, simulating narrowband connections.

• Full Duplex Proxy Fun
  Handles bidirectional TCP traffic between clients and target servers with independent impairment streams.

• Thread-Safe Logging System
  All events are timestamped and written both on screen and a log file.

• Live Configuration Display
  Shows current configuration parameters upon startup for verification.

Note: NeckSim Pro does not handle SSL/TLS termination. It does not look inside data to see if it is HTTP, or if it's encrypted using SSL/TLS (denoted by HTTPS).

Disclaimer: You can only use NeckSim Pro inside your own private network(s) or local virtual machines. Using these types of tools against a third-party server (not including www.example.com) may violate that server's Terms of Service (ToS) and could lead to you being blocked or investigated for malicious activity.

Version history

• ver 1.0 - First Release (October 2025)