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Compress and decompress arbitrary network streams.
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Compress and decompress arbitrary network streams.

Boildown listens on a local port, compresses (or decompresses) incoming traffic, and forwards the result to its destination. It's like SSH port-forwarding, but the bidirectional network traffic flowing through Boildown is automatically compressed or decompressed, depending on how it's configured. In essence, Boildown provides a compressed "pipe" connecting two nodes on a network.

Boildown is entirely protocol agnostic — it knows nothing about the protocol of the data flowing through it, and works transparently with any protocol that can be expressed over TCP/IP. The most common being HTTP (port 80), HTTPS (port 443), and SSH (port 22).

Boildown currently supports the following framed or "block" codecs:


From a remote location, I SSH home quite regularly and port-forward to several services behind NAT on my home network: SSH, remote desktop, web-cams, etc. I was curious to see if I could write something general that compresses traffic over a socket in an attempt to improve the overall "remote experience".

And, I just wanted an excuse to play with LZF and Snappy.


There's two sides (or "modes") to Boildown:

  • Compressor — listens on a local port, compresses outgoing traffic, and forwards the compressed data to another host.
  • Decompressor — listens on a local port, decompresses incoming traffic, and forwards the original (uncompressed) result to its destination.

Here's how you'd create a compressed pipe using Boildown for an SSH session between localhost:10022 and remote:22:

+--------- [localhost] ---------+                               +----------- [remote] ------------+
| --compress 10022:remote:10022 | <---- (compressed pipe) ----> | --decompress 10022:localhost:22 |
+-------------------------------+                               +---------------------------------+

A Boildown compressor listens at localhost:10022 and forwards compressed traffic to the decompressor listening at remote:10022. Any bytes received by the decompressor at remote:10022 are decompressed and forwarded to the SSH server daemon listening locally on localhost:22. Of course, traffic flowing the other way, remote:22 back to localhost:10022, is compressed and decompressed in the same way.

Hence, a bidirectional, compressed network pipe.

On localhost

Start a compressor on localhost:10022, forwarding compressed traffic to remote:10022:

java -jar boildown-0.1-SNAPSHOT-runnable.jar --compress 10022:remote:10022 --zlib

On remote

Start a decompressor on remote:10022, forwarding decompressed traffic to localhost:22:

java -jar boildown-0.1-SNAPSHOT-runnable.jar --decompress 10022:localhost:22 --zlib

Connect the dots

On localhost, start a new SSH session, funneling traffic through the Boildown managed compressed pipe:

ssh -p 10022 localhost

Compression codecs

Specify --zlib, --snappy, or --lzf on the command line to use any of the 3 supported compression codecs.

Note, both sides of the pipe need to be using the same codec (obviously).

Thread pool

The compressor and decompressor implementations run within threads. The size of the internal thread pool used by Boildown can be controlled with the --poolSize argument.

By default, if --poolSize is omitted, the internal thread pool is sized to match the number of available cores.


Boildown is built and packaged using Maven.

To build, clone the repository:

#~> git clone

Run mvn package to compile and build a runnable JAR:

#~> cd boildown
#~> mvn package

The resulting runnable JAR will be placed in the dist directory.


Copyright (c) 2016 Mark S. Kolich

All code in this project is freely available for use and redistribution under the MIT License.

See LICENSE for details.

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