chisel

Chisel is a fast TCP tunnel, transported over HTTP, secured via SSH. Single executable including both client and server. Written in Go (golang). Chisel is mainly useful for passing through firewalls, though it can also be used to provide a secure endpoint into your network. Chisel is very similar to crowbar though achieves much higher performance.

Features

Easy to use
Performant*
Encrypted connections using the SSH protocol (via crypto/ssh)
Authenticated connections; authenticated client connections with a users config file, authenticated server connections with fingerprint matching.
Client auto-reconnects with exponential backoff
Client can create multiple tunnel endpoints over one TCP connection
Client can optionally pass through HTTP CONNECT proxies
Server optionally doubles as a reverse proxy
Server optionally allows SOCKS5 connections (See guide below)

Install

Binaries

See the latest release or download and install it now with curl https://i.jpillora.com/chisel! | bash

Docker

docker run --rm -it jpillora/chisel --help

Source

$ go get -v github.com/jpillora/chisel

Demo

A demo app on Heroku is running this chisel server:

$ chisel server --port $PORT --proxy http://example.com
# listens on $PORT, proxy web requests to 'http://example.com'

This demo app is also running a simple file server on :3000, which is normally inaccessible due to Heroku's firewall. However, if we tunnel in with:

$ chisel client https://chisel-demo.herokuapp.com 3000
# connects to 'https://chisel-demo.herokuapp.com',
# tunnels your localhost:3000 to the server's localhost:3000

and then visit localhost:3000, we should see a directory listing of the demo app's root. Also, if we visit the demo app in the browser we should hit the server's default proxy and see a copy of example.com.

Usage

$ chisel --help

   Usage: chisel [command] [--help]

   Version: X.Y.Z

   Commands:
     server - runs chisel in server mode
     client - runs chisel in client mode

   Read more:
     https://github.com/jpillora/chisel

$ chisel server --help

  Usage: chisel server [options]

  Options:

    --host, Defines the HTTP listening host – the network interface
    (defaults the environment variable HOST and falls back to 0.0.0.0).

    --port, -p, Defines the HTTP listening port (defaults to the environment
    variable PORT and fallsback to port 8080).

    --key, An optional string to seed the generation of a ECDSA public
    and private key pair. All commications will be secured using this
    key pair. Share the subsequent fingerprint with clients to enable detection
    of man-in-the-middle attacks (defaults to the CHISEL_KEY environment
    variable, otherwise a new key is generate each run).

    --authfile, An optional path to a users.json file. This file should
    be an object with users defined like:
      {
        "<user:pass>": ["<addr-regex>","<addr-regex>"]
      }
    when <user> connects, their <pass> will be verified and then
    each of the remote addresses will be compared against the list
    of address regular expressions for a match. Addresses will
    always come in the form "<host/ip>:<port>".

    --auth, An optional string representing a single user with full
    access, in the form of <user:pass>. This is equivalent to creating an
    authfile with {"<user:pass>": [""]}.

    --proxy, Specifies another HTTP server to proxy requests to when
    chisel receives a normal HTTP request. Useful for hiding chisel in
    plain sight.

    --socks5, Allows client to access the internal SOCKS5 proxy. See
    chisel client --help for more information.

    --pid Generate pid file in current directory

    -v, Enable verbose logging

    --help, This help text

  Version:
    X.Y.Z

  Read more:
    https://github.com/jpillora/chisel

$ chisel client --help

  Usage: chisel client [options] <server> <remote> [remote] [remote] ...

  <server> is the URL to the chisel server.

  <remote>s are remote connections tunnelled through the server, each of
  which come in the form:

    <local-host>:<local-port>:<remote-host>:<remote-port>

    ■ local-host defaults to 0.0.0.0 (all interfaces).
    ■ local-port defaults to remote-port.
    ■ remote-port is required*.
    ■ remote-host defaults to 0.0.0.0 (server localhost).

    example remotes

      3000
      example.com:3000
      3000:google.com:80
      192.168.0.5:3000:google.com:80
      socks
      5000:socks

    *When the chisel server has --socks5 enabled, remotes can
    specify "socks" in place of remote-host and remote-port.
    The default local host and port for a "socks" remote is
    127.0.0.1:1080. Connections to this remote will terminate
    at the server's internal SOCKS5 proxy.

  Options:

    --fingerprint, A *strongly recommended* fingerprint string
    to perform host-key validation against the server's public key.
    You may provide just a prefix of the key or the entire string.
    Fingerprint mismatches will close the connection.

    --auth, An optional username and password (client authentication)
    in the form: "<user>:<pass>". These credentials are compared to
    the credentials inside the server's --authfile. defaults to the
    AUTH environment variable.

    --keepalive, An optional keepalive interval. Since the underlying
    transport is HTTP, in many instances we'll be traversing through
    proxies, often these proxies will close idle connections. You must
    specify a time with a unit, for example '30s' or '2m'. Defaults
    to '0s' (disabled).

    --proxy, An optional HTTP CONNECT proxy which will be used reach
    the chisel server. Authentication can be specified inside the URL.
    For example, http://admin:password@my-server.com:8081

    --max-retry-count, Maximum number of times to retry before exiting.
    Defaults to unlimited.

    --max-retry-interval, Maximum wait time before retrying after a
    disconnection. Defaults to 5 minutes.

    --pid Generate pid file in current directory

    -v, Enable verbose logging

    --help, This help text

  Version:
    X.Y.Z

  Read more:
    https://github.com/jpillora/chisel

Security

Encryption is always enabled. When you start up a chisel server, it will generate an in-memory ECDSA public/private key pair. The public key fingerprint will be displayed as the server starts. Instead of generating a random key, the server may optionally specify a key seed, using the --key option, which will be used to seed the key generation. When clients connect, they will also display the server's public key fingerprint. The client can force a particular fingerprint using the --fingerprint option. See the --help above for more information.

Authentication

Using the --authfile option, the server may optionally provide a user.json configuration file to create a list of accepted users. The client then authenticates using the --auth option. See users.json for an example authentication configuration file. See the --help above for more information.

Internally, this is done using the Password authentication method provided by SSH. Learn more about crypto/ssh here http://blog.gopheracademy.com/go-and-ssh/.

SOCKS5 Guide

Start your chisel server

docker run \
  --name chisel -p 9312:9312 \
  -d --restart always \
  jpillora/chisel server -p 9312 --socks5 --key supersecret

Connect your chisel client (using server's fingerprint)

chisel client --fingerprint ab:12:34 server-address:9312 socks

Point your SOCKS5 clients (e.g. OS/Browser) to:

localhost:1080

Now you have an encrypted, authenticated SOCKS5 connection over HTTP

Performance

With crowbar, a connection is tunnelled by repeatedly querying the server with updates. This results in a large amount of HTTP and TCP connection overhead. Chisel overcomes this using WebSockets combined with crypto/ssh to create hundreds of logical connections, resulting in one TCP connection per client.

In this simple benchmark, we have:

					(direct)
        .--------------->----------------.
       /    chisel         chisel         \
request--->client:2001--->server:2002---->fileserver:3000
       \                                  /
        '--> crowbar:4001--->crowbar:4002'
             client           server

Note, we're using an in-memory "file" server on localhost for these tests

direct

:3000 => 1 bytes in 1.291417ms
:3000 => 10 bytes in 713.525µs
:3000 => 100 bytes in 562.48µs
:3000 => 1000 bytes in 595.445µs
:3000 => 10000 bytes in 1.053298ms
:3000 => 100000 bytes in 741.351µs
:3000 => 1000000 bytes in 1.367143ms
:3000 => 10000000 bytes in 8.601549ms
:3000 => 100000000 bytes in 76.3939ms

chisel

:2001 => 1 bytes in 1.351976ms
:2001 => 10 bytes in 1.106086ms
:2001 => 100 bytes in 1.005729ms
:2001 => 1000 bytes in 1.254396ms
:2001 => 10000 bytes in 1.139777ms
:2001 => 100000 bytes in 2.35437ms
:2001 => 1000000 bytes in 11.502673ms
:2001 => 10000000 bytes in 123.130246ms
:2001 => 100000000 bytes in 966.48636ms

~100MB in ~1 second

crowbar

:4001 => 1 bytes in 3.335797ms
:4001 => 10 bytes in 1.453007ms
:4001 => 100 bytes in 1.811727ms
:4001 => 1000 bytes in 1.621525ms
:4001 => 10000 bytes in 5.20729ms
:4001 => 100000 bytes in 38.461926ms
:4001 => 1000000 bytes in 358.784864ms
:4001 => 10000000 bytes in 3.603206487s
:4001 => 100000000 bytes in 36.332395213s

~100MB in 36 seconds

See more test/

Known Issues

WebSockets support is required _ IaaS providers all will support WebSockets _ Unless an unsupporting HTTP proxy has been forced in front of you, in which case I'd argue that you've been downgraded to PaaS. _ PaaS providers vary in their support for WebSockets _ Heroku has full support _ Openshift has full support though connections are only accepted on ports 8443 and 8080 _ Google App Engine has no support (Track this on their repo)

Contributing

http://golang.org/doc/code.html
http://golang.org/doc/effective_go.html
github.com/jpillora/chisel/share contains the shared package
github.com/jpillora/chisel/server contains the server package
github.com/jpillora/chisel/client contains the client package

Changelog

1.0.0 - Initial release
1.1.0 - Swapped out simple symmetric encryption for ECDSA SSH
1.2.0 - Added SOCKS5 (server) and HTTP CONNECT (client) support

Todo

Allow clients to act as an indirect tunnel endpoint for other clients
Better, faster tests
Expose a stats page for proxy throughput
Treat client stdin/stdout as a socket

MIT License

Copyright © 2017 Jaime Pillora <dev@jpillora.com>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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