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emissary: A TCP service multiplexer

emissary provides a command to multiplex TCP services on the same port, and route connections to different upstream addresses based on their starting bytes.

Upstreams are configured through upstream rules, which are a simple regexp/remote address pair.

Installation

With go get

$ go get github.com/darvid/emissary

Binaries

The latest releases can be downloaded from Github.

From source

$ git clone https://github.com/darvid/emissary.git
$ cd emissary
# Requires Glide to be installed - https://glide.sh/
$ glide install
$ make build

Examples

# Forward all HTTP GET requests to httpbin.org
$ emissary -bind localhost:1080 -upstream '/^GET/:httpbin.org:80'

# Forward SOCKS5 traffic to a local SOCKS5 server
$ emissary -bind localhost:1080 -upstream '/^\x05/:localhost:1081'

Any number of upstreams may be chained together.

Usage

Usage of emissary:
  -alsologtostderr
        log to standard error as well as files
  -bind string
        bind address (default "localhost:1080")
  -buffersize int
        buffer size for first read (default 4096)
  -log_backtrace_at value
        when logging hits line file:N, emit a stack trace (default :0)
  -log_dir string
        If non-empty, write log files in this directory
  -logtostderr
        log to standard error instead of files
  -stderrthreshold value
        logs at or above this threshold go to stderr
  -upstream value
        list of upstream rules (default [])
  -v value
        log level for V logs
  -version
        show version
  -vmodule value
        comma-separated list of pattern=N settings for file-filtered logging

Similar projects

A few projects exist that provide TCP service muxing. The ones mentioned below are libraries which require writing custom applications or scripts, which may be preferential to some, depending on the use case.

• Emissary
• node-port-mux
• cmux