drsh

drsh

drsh stands for David's Remote SHell. It is a custom implementation of a remote shell protocol that routes all traffic through a mutually agreed upon Redis instance rather than directly from client to server. One might describe drsh as a variant of ssh specifically designed with the functionality of ngrok.

More about drsh:

• All clients & servers connecting to one Redis instance are assumpted to be mutually trusted. That is, if a user can access a Redis instance, they can freely log on to any server connected to the same Redis node.
• However, once a secure channel has be set up between a specific client and server, any content passing through the channel cannot be inspected by other parties on the instance, as all subsequent messages past the handshake are encrypted.
• Forward secrecy is implemented by generating ephemeral keys from secure randomness.
• Keys are exchanged using the Diffie-Helman key exchange algorithm.
• Messages are encrypted using the ChaCha20-Poly1305 AEAD cipher.

Setup

Installation

You can install drsh locally using go get. Make sure you are using go version 1.13+.

GO111MODULE=on go get -v github.com/dmhacker/drsh/cmd/drsh@latest

You can also update drsh using the same command.

Try generating a default configuration file using the following:

drsh config

Configuration

Both servers and clients on the same machine use only one config located at $HOME/.drsh/config.yml. This location can be changed using the --config option.

The config is structured in two parts, a server section and a client section.

• The server section has a hostname and redisuri field. The URI specifies the Redis node that the server should connect to. The hostname specifies what the machine's unique name in the network is.
• The client section has an aliases section. An alias represents a saved combination for connecting as a specific user on a reachable host through some Redis instance. Aliases are required for all client commands to minimize leakage of sensitive connection details on the command line.

Please also note that while servers can be run as root and have access to logins as root, the practice of logging in as a root as a client is explicitly forbid. Unlike SSH, there is no option to enable this functionality.

Servers

Running the server is simple.

drsh serve

Use the -h flag for help.

Clients

Connecting to a server is also simple.

drsh login [alias]

Additionally, files can be uploaded to and downloaded from the server.

drsh upload [alias] [local_file] [remote_file]
drsh download [alias] [remote_file] [local_file]

There is also a ping command that measures the latency between a client and server, with the packets passing through Redis.

drsh ping [alias]

Again, use the -h flag for help.