ssh2.cr

This library provides binding for libssh2 library.

Requirements

• libssh2 version 1.11.0 or higher

You can use homebrew to install the latest libssh2:

$ brew install libssh2

Installation

Add the shard to your shard.yml:

dependencies:
  ssh2:
    github: spider-gazelle/ssh2.cr

Then run:

shards install

Goal

The goal is to utilize libssh2 API by providing services like ability to run shell commands via ssh as well as scp and sftp services.

Usage

An example of running a shell command via SSH on the remote server:

require "ssh2"

SSH2::Session.open("my_server") do |session|
  session.login("username", "password")
  session.open_session do |channel|
    channel.command("uptime")
    IO.copy(channel, STDOUT)
  end
end

An example of running shell:

require "ssh2"

session = SSH2::Session.connect("localhost", 2222)
session.login("root", "somepassword")
channel = session.open_session

# request the terminal has echo mode off
channel.request_pty("vt100", [{SSH2::TerminalMode::ECHO, 0u32}])
channel.shell

# Send commands
spawn {
  list = ["ls\n", "ps aux\n", "uptime\n"]
  loop do
    channel.write(list.sample(1)[0].to_slice)
    sleep 3
  end
}

# Receive responses
raw_data = Bytes.new(2048)
loop do
  bytes_read = channel.read(raw_data)
  puts String.new(raw_data[0, bytes_read])
end

An example of transferring files over SCP:

require "ssh2"

SSH2::Session.open("localhost", 2222) do |session|
  session.login("root", "somepassword")
  # upload a local file, then download it back
  session.scp_send_file("./hello.txt", "/tmp/hello.txt")
  session.scp_recv_file("/tmp/hello.txt", "./hello-copy.txt")
end

An example of using SFTP API:

require "ssh2"

SSH2::Session.open("localhost", 2222) do |session|
  # NOTE:: ED25519 based keys only work on latest versions of libssh2
  session.login_with_pubkey("root", "./spec/keys/id_rsa", "./spec/keys/id_rsa.pub")
  session.sftp_session do |sftp|
    sftp.open_dir(".").ll do |fn|
      puts fn
    end
    file = sftp.open(".bashrc")
    puts file.gets_to_end
  end
end

Development

This project uses mise to manage the Crystal toolchain and the developer tasks (mise tasks lists them all). Install the dependencies with:

mise dev:deps

Testing

The suite is split in two tiers:

• Unit specs are serverless and run everywhere:

  mise dev:spec       # single-threaded
  mise dev:spec-mt    # multi-threaded (fiber-safety gate)
  

• Integration specs drive a real SSH server (a testcontainers/sshd container defined in docker-compose.yml) and are gated behind -Dintegration:

  mise dev:ssh-up             # start the container
  mise dev:spec-integration   # run the e2e suite
  mise dev:ssh-down           # stop it
  

Connection settings default to the container (localhost:10022, root / somepassword) and can be overridden via the SPEC_SSH_HOST, SPEC_SSH_PORT, SPEC_SSH_USER and SPEC_SSH_PASS environment variables.

License

MIT clause - see LICENSE for more details. Many thanks to the original author Kent Sibilev