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.
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
- Clients can create multiple tunnel endpoints over one TCP connection
- Clients can optionally pass through SOCKS or HTTP CONNECT proxies
- Reverse port forwarding (Connections go through the server and out the client)
- Server optionally doubles as a reverse proxy
- Server optionally allows SOCKS5 connections (See guide below)
- Clients optionally allow SOCKS5 connections from a reversed port forward
- Client connections over stdio which supports
ssh -o ProxyCommandproviding SSH over HTTP
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 chisel server at 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. 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: 0.0.0-src (go1.14.5)
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 communications 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 "<remote-host>:<remote-port>" for normal remotes
and "R:<local-interface>:<local-port>" for reverse port forwarding
remotes. This file will be automatically reloaded on change.
--auth, An optional string representing a single user with full
access, in the form of <user:pass>. It is equivalent to creating an
authfile with {"<user:pass>": [""]}. If unset, it will use the
environment variable AUTH.
--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 '5s' or '2m'. Defaults
to '25s' (set to 0s to disable).
--proxy, Specifies another HTTP server to proxy requests to when
chisel receives a normal HTTP request. Useful for hiding chisel in
plain sight.
--socks5, Allow clients to access the internal SOCKS5 proxy. See
chisel client --help for more information.
--reverse, Allow clients to specify reverse port forwarding remotes
in addition to normal remotes.
--tls-key, Enables TLS and provides optional path to a PEM-encoded
TLS private key. When this flag is set, you must also set --tls-cert,
and you cannot set --tls-domain.
--tls-cert, Enables TLS and provides optional path to a PEM-encoded
TLS certificate. When this flag is set, you must also set --tls-key,
and you cannot set --tls-domain.
--tls-domain, Enables TLS and automatically acquires a TLS key and
certificate using LetsEncypt. Setting --tls-domain requires port 443.
You may specify multiple --tls-domain flags to serve multiple domains.
The resulting files are cached in the "$HOME/.cache/chisel" directory.
You can modify this path by setting the CHISEL_LE_CACHE variable,
or disable caching by setting this variable to "-". You can optionally
provide a certificate notification email by setting CHISEL_LE_EMAIL.
--pid Generate pid file in current working directory
-v, Enable verbose logging
--help, This help text
Signals:
The chisel process is listening for:
a SIGUSR2 to print process stats, and
a SIGHUP to short-circuit the client reconnect timer
Version:
0.0.0-src (go1.14.5)
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 tunneled 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).
which shares <remote-host>:<remote-port> from the server to the client
as <local-host>:<local-port>, or:
R:<local-interface>:<local-port>:<remote-host>:<remote-port>
which does reverse port forwarding, sharing <remote-host>:<remote-port>
from the client to the server's <local-interface>:<local-port>.
example remotes
3000
example.com:3000
3000:google.com:80
192.168.0.5:3000:google.com:80
socks
5000:socks
R:2222:localhost:22
R:socks
R:5000:socks
stdio:example.com:22
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.
When the chisel server has --reverse enabled, remotes can
be prefixed with R to denote that they are reversed. That
is, the server will listen and accept connections, and they
will be proxied through the client which specified the remote.
Reverse remotes specifying "R:socks" will listen on the server's
default socks port (1080) and terminate the connection at the
client's internal SOCKS5 proxy.
When stdio is used as local-host, the tunnel will connect standard
input/output of this program with the remote. This is useful when
combined with ssh ProxyCommand. You can use
ssh -o ProxyCommand='chisel client chiselserver stdio:%h:%p' \
[email protected]
to connect to an SSH server through the tunnel.
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 '5s' or '2m'. Defaults
to '25s' (set to 0s to disable).
--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.
--proxy, An optional HTTP CONNECT or SOCKS5 proxy which will be
used to reach the chisel server. Authentication can be specified
inside the URL.
For example, http://admin:[email protected]:8081
or: socks://admin:[email protected]:1080
--header, Set a custom header in the form "HeaderName: HeaderContent".
Can be used multiple times. (e.g --header "Foo: Bar" --header "Hello: World")
--hostname, Optionally set the 'Host' header (defaults to the host
found in the server url).
--pid Generate pid file in current working directory
-v, Enable verbose logging
--help, This help text
Signals:
The chisel process is listening for:
a SIGUSR2 to print process stats, and
a SIGHUP to short-circuit the client reconnect timer
Version:
0.0.0-src (go1.14.5)
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:
<client-address>:1080
- Now you have an encrypted, authenticated SOCKS5 connection over HTTP
Caveats
Since 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/sharecontains the shared packagegithub.com/jpillora/chisel/servercontains the server packagegithub.com/jpillora/chisel/clientcontains the client package
Changelog
1.0- Initial release1.1- Replaced simple symmetric encryption for ECDSA SSH1.2- Added SOCKS5 (server) and HTTP CONNECT (client) support1.3- Added reverse tunnelling support1.4- Added arbitrary HTTP header support1.5- Added reverse SOCKS support (by @aus)1.6- Added client stdio support (by @BoleynSu)1.7- Added UDP support