MacOS 12.5.1 (M1 Max)
Elixir 1.14.3 (compiled with Erlang/OTP 25)

I am trying to read some status data from a network switch within my Elixir application over ssh. I am attempting to do this using the SSHEx framework.

I am able to connect fine (returns ok, and I can see an open session on the switch), but when I issues a command I am unable to read any response, and it times out waiting.

To confirm I have started :ssh under Extra Application.

Here is the code I am using initially, I’m aware it’s not ideal at the moment, but it should at least be getting me some output.

    defmodule FibreTestUi.Ssh do
      defp connect do
        SSHEx.connect(
          ip: '192.168.1.1',
          user: 'admin',
          password: '!Password',
          modify_algorithms: [
            {:append, [{:kex, [:"diffie-hellman-group-exchange-sha1"]}]},
            {:append, [{:public_key, [:"ssh-rsa", :"ssh-dss"]}]}
          ]
        )
      end
    
      def list_port_status do
        {:ok, conn} = connect()
        SSHEx.cmd!(conn, 'show ssh', exec_timeout: 15000)
      end
    end

All I get back is:

    ** (RuntimeError) {:error, "Timeout. Did not receive data for 15000ms."}
        (sshex 2.2.1) lib/sshex.ex:100: SSHEx.cmd!/3
        iex:2: (file)

If I ssh into the switch manually, I am able to execute the command fine.

    user@comp ~ % ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 admin@192.168.1.1
    
    
    FS#show ssh
    Connection Version Encryption       Hmac         Compress   State           Username
             0     2.0 aes128-ctr       hmac-sha1    none       Session started admin
    FS#

If I pick another random device (ransom raspberry pi), and connect with a basic ‘echo hello’ I get a response fine.

    defmodule FibreTestUi.Ssh do
      defp connect do
        SSHEx.connect(
          ip: '10.11.xx.xx',
          user: 'pi',
          password: 'password',
          modify_algorithms: [
            {:append, [{:kex, [:"diffie-hellman-group-exchange-sha1"]}]},
            {:append, [{:public_key, [:"ssh-rsa", :"ssh-dss"]}]}
          ]
        )
      end
    
      def list_port_status do
        {:ok, conn} = connect()
        SSHEx.cmd!(conn, 'echo hello', exec_timeout: 5000)
      end
    end

"hello\n"

I have also tried doing this directly using :ssh with the following code:

      def send_command do
        {:ok, ssh_pid} =
          :ssh.connect('192.168.1.1', 22,
            user: 'admin',
            save_accepted_host: false,
            silently_accept_hosts: true,
            password: '!Password',
            modify_algorithms: [
              prepend: [kex: [:"diffie-hellman-group1-sha1", :"diffie-hellman-group-exchange-sha1"]],
              prepend: [public_key: [:"ssh-rsa", :"ssh-dss"]]
            ]
          )
    
        {:ok, chn} = :ssh_connection.session_channel(ssh_pid, 5000)
    
        _success = :ssh_connection.exec(ssh_pid, chn, 'show ssh', 5000)
    
        # for _ <- 0..1 do
        receive do
          {:ssh_cm, ^ssh_pid, value} -> IO.inspect(value)
        after
          5000 ->
            IO.puts(:stderr, "No message in 5 seconds")
        end
    
        :ok = :ssh.close(ssh_pid)
      end

The response I get is this, for every command, no matter what command I send.

    iex(20)> FibreTestUi.Ssh.send_command    
    {:data, 0, 0,
     <<2, 83, 67, 80, 58, 32, 83, 67, 80, 32, 83, 101, 114, 118, 101, 114, 32, 83,
       101, 114, 118, 105, 99, 101, 32, 105, 115, 32, 100, 105, 115, 97, 98, 108,
       101, 33, 10>>}

So it seems to be something specific to this device, but I can’t really work out what that would be. Anyone got any thoughts?