hoerzu

hoerzu - a small eavesdropping TCP proxy

hoerzu is a TCP relay/proxy between a remote server and clients. There are two kinds of clients:

1. Bidirectional: Clients doing two-way communication with the remote server over the hoerzu proxy.
2. Eavesdropping: Clients listening to the data comming from the remote server. Traffic from the bidirectional clients is not recorded.

Each connected bidirectional client starts a session. A session has exactly one bidirectional client. Eavesdropping clients can connect or disconnect to or from a session to follow the traffic send from the remote server to the bidirectional client. A session is killed when the connection to the bidirectional is cut or the remote server cuts the connection to the hoerzu server.

Build

You need a working Go build environment (Tested successfully with Go 1.9+).

go get -u -v bitbucket.org/intevation/hoerzu/cmd/hoerzu

Place the resulting hoerzu binary into your PATH.

Usage

To see all options use the -h/--help flag:

NAME:
   hoerzu - A simple eavesdropping TCP proxy server.

USAGE:
   hoerzu [global options] command [command options] [arguments...]

VERSION:
   0.1

COMMANDS:
     help, h  Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --remote HOST          remote HOST to connect to (default: "localhost")
   --remote-port PORT     remote PORT to connect to (default: 8080)
   --listen HOST          listen HOST (default: "localhost")
   --listen-port PORT     listen PORT (default: 8899)
   --eavesdrop HOST       eavesdrop HOST (default: "localhost")
   --eavesdrop-port PORT  eavesdrop PORT (default: 8889)
   --timeout DURATION     DURATION before disconnecting a stale client. 0s: no timeout (default: 0s)
   --log-level LEVEL      Log LEVEL: debug, info, warn, error, fatal, panic (default: "info")
   --log-file FILE        write log in FILE
   --load FILE            load configuration from FILE
   --help, -h             show help
   --version, -v          print the version

The options can be stored in a TOML file and used with the --load flag.
See example.toml for an example.

Performance

Some preliminary measurements.

License

(c) 2017 Intevation GmbH. Development sponsored by Siemens AG.
This is Free Software covered by the terms of the Apache 2 license.
See LICENSE for details.