Cloak

Cloak 2 is a WIP and not ready for release. Cloak 2 will not be compatible with Cloak 1 protocols or configurarion files

Cloak is a universal pluggable transport that obfuscates proxy traffic as legitimate HTTPS traffic, disguises the proxy server as a normal webserver, multiplexes traffic through multiple TCP connections and provide multi-user usage control.

Cloak eliminates any "fingerprints" exposed by traditional proxy protocol designs which can be identified by adversaries through deep packet inspection. If a non-Cloak program or an unauthorised Cloak user (such as an adversary's prober) attemps to connect to Cloak server, it will serve as a transparent proxy between said machine and an ordinary website, so that to any unauthorised third party, a host running Cloak server is indistinguishable from an innocent web server.

Since Cloak is transparent, it can be used in conjunction with any proxy softwares that tunnels traffic through TCP, such as Shadowsocks, OpenVPN and Tor. Multiple proxy servers can be running on the same server host machine and Cloak will act as a dispatcher, bridging clients with their desired proxy end.

Cloak multiplexes traffic through multiple underlying TCP connections which reduces head-of-line blocking and eliminates TCP handshake overhead.

Cloak provides multi-user support, allowing multiple clients to connect to the proxy server on the same port (443 by default). It also provides QoS controls for individual users such as data limit and bandwidth control.

This project is based on GoQuiet. Through multiplexing, Cloak provides a siginifcant reduction in webpage loading time compared to GoQuiet (from 10% to 50%+, depending on the amount of content on the webpage, see benchmarks).

Build

Simply make client and make server. Output binary will be in build folder. Do make server_pprof if you want to access the live profiling data.

Configuration

Server

RedirAddr is the redirection address and port when the incoming traffic is not from a Cloak client. It should correspond to the IP record of the ServerName field set in ckclient.json.

ProxyMethod is a nested JSON section which defines the address of different proxy server ends. For instance, if OpenVPN server is listening on 127.0.0.1:1194, the pair should be "openvpn":"127.0.0.1:1194". There can be multiple pairs.

PrivateKey is the static curve25519 Diffie-Hellman private key encoded in base64.

AdminUID is the UID of the admin user in base64.

DatabasePath is the path to userinfo.db. If userinfo.db doesn't exist in this directory, Cloak will create one automatically. If Cloak is started as a Shadowsocks plugin and Shadowsocks is started with its working directory as / (e.g. starting ss-server with systemctl), you need to set this field as an absolute path to a desired folder. If you leave it as default then Cloak will attempt to create userinfo.db under /, which it doesn't have the permission to do so and will raise an error. See Issue #13.

BackupDirPath is the path to save the backups of userinfo.db whenever you delete a user. If left blank, Cloak will attempt to create a folder called db-backup under its working directory. This may not be desired. See notes above.

Client

UID is your UID in base64.

PublicKey is the static curve25519 public key, given by the server admin.

ProxyMethod is the name of the proxy method you are using.

EncryptionMethod is the name of the encryption algorithm you want Cloak to use. Note: Cloak isn't intended to provide data security or authentication. The point of encryption is to hide fingerprints of proxy protocols. If the proxy protocol already doesn't have any fingerprint, such as Shadowsocks, this field can be left as plain. Options are plain, aes-gcm and chacha20-poly1305.

ServerName is the domain you want to make your ISP or firewall think you are visiting.

TicketTimeHint is the time needed for a session ticket to expire and a new one to be generated. Leave it as the default.

NumConn is the amount of underlying TCP connections you want to use.

BrowserSig is the browser you want to make the GFW think you are using, it has NOTHING to do with the web browser or any web application you are using on your machine. Currently, chrome and firefox are supported.

Setup

For the administrator of the server

Run this script: https://github.com/HirbodBehnam/Shadowsocks-Cloak-Installer/blob/master/Shadowsocks-Cloak-Installer.sh (thanks to @HirbodBehnam) or do it manually:

0. Install and configure shadowsocks-libev on your server
1. Download the latest release or clone and build this repo. If you wish to build it, make sure you fetch the dependencies using go get github.com/boltdb/bolt, go get github.com/juju/ratelimit and go get golang.org/x/crypto/curve25519
2. Run ck-server -k. The base64 string before the comma is the public key to be given to users, the one after the comma is the private key to be kept secret
3. Run ck-server -u. This will be used as the AdminUID
4. Put the private key and the AdminUID you obtained previously into config/ckserver.json
5. Edit the configuration file of shadowsocks-libev (default location is /etc/shadowsocks-libev/config.json). Let server_port be 443, plugin be the full path to the ck-server binary and plugin_opts be the full path to ckserver.json. If the fields plugin and plugin_opts were not present originally, add these fields to the config file.
6. Run ss-server as root (because we are binding to TCP port 443)

If you want to add more users

1. Run ck-server -u to generate a new UID
2. On your client, run ck-client -a -c <path-to-ckclient.json> to enter admin mode
3. Input as prompted, that is your ip:port of the server and your AdminUID. Enter 4 to create a new user.
4. Enter the the newly generated UID, enter SessionsCap (maximum amount of concurrent sessions a user can have), UpRate and DownRate (in bytes/s), UpCredit and DownCredit (in bytes) and ExpiryTime (as a unix epoch)
5. Give your public key and the newly generated UID to the new user

Note: the user database is persistent as it's in-disk. You don't need to add the users again each time you start ck-server.

Instructions for clients

Android client is available here: https://github.com/cbeuw/Cloak-android

0. Install and configure a version of shadowsocks client that supports plugins (such as shadowsocks-libev and shadowsocks-windows)
1. Download the latest release or clone and build this repo. If you wish to build it, make sure you fetch the dependencies using go get github.com/boltdb/bolt, go get github.com/juju/ratelimit and go get golang.org/x/crypto/curve25519
2. Obtain the public key and your UID (or the AdminUID, if you are the server admin) from the administrator of your server
3. Put the public key and the UID you obtained into config/ckclient.json
4. Configure your shadowsocks client with your server information. The field plugin should be the path to ck-server binary and plugin_opts should be the path to ckclient.json

Support me

If you find this project useful, donations are greatly appreciated!

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