NetSplitter

NetSplitter is a small tool to duplicate a network stream to another computer. It acts as a proxy that forward a stream to a main target while duplicating the same stream to other secondary targets.

It can be used in several day-to-day scenarii:

• Simulate load on a web server, by duplicating a single stream on the same target multiple times
• Duplicate production load on a development machine in order to easily debug in production environment
• Duplicate a production network stream on a backup server

It can be used as a L4 TCP proxy, or as a L7 HTTP reverse proxy. The HTTP layer will handle Host add X-Forwarded-For headers.

NetSplitter aims to directly forward a stream to the main target. Only the main target can respond to clients. A copy of each received buffer will be stored in secondary targets buffer, until sent. If a secondary target does not process data quickly enough or does not respond, it will be discarded.

Usage

NetSplitter uses an JSON configuration file to describe its behavior, automatically reloaded upon modification.

Here is a sample configuration file

{
    "Settings":
    {
        "Mode": "Http", // Tcp, Http
        "Port": 80,
        "Balancing": "Random", // Random, IPHash, LeastConn
        "BufferSize": 1048576,
        "Timeout": 1000
    },
    "Balancing":
    [
        { "Hostname": "prod1", "Port": 80, "Weight": 2 },
        { "Hostname": "prod2", "Port": 80 },
        { "Hostname": "prod3", "Port": 80, "Enabled": false }
    ],
    "Cloning":
    [
        { "Hostname": "127.0.0.1", "Port": 8080 }
        { "Hostname": "dev1", "Port": 8080, "Enabled": false }
    ]
}

• Settings.Port: (Mandatory) Port to listen to
• Settings.Mode: Mode to use to proxy requests
  • TCP: L4 proxy
  • HTTP: L7 proxy, with support for Host and X-Forwarded-For headers
• Settings.Balancing: Balancing mode to use to select the master target
  • Random: A random target will be selected according to specified weights
  • IPHash: Each client IP will have a deterministic target according to specified weights. This mode can be used to ensure that a client always connect to the same server, for HTTP website for examples
  • LeastConn: The target with the least number of connection will get the new one, according to specified weights
• Settings.BufferSize: Maximum buffer size to use per connection
• Settings.Timeout: Timeout in ms after which secondary targets will be discarded
• Settings.Target: Description of the main target to communicate to
• Balancing.*: List of master hosts to connect to
• Cloning.*: List of secondary hosts
  • .Hostname: (Mandatory) Target to connect to
  • .Port: (Mandatory) Target port to connect to
  • .Weight: Weight of this target. A greater weight means it will be choosen more often. Default is 1
  • .Enabled: Use false to disable this target

If not specified, NetSplitter will automatically choose HTTP mode and IPHash balancing if you specify port 80, 1080 or 8080.