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c#.net pass confirm operation in Telnet connection

I am writing a program with c# and .net core 3.1 which connecting to a UPS (Uninterruptible power supply) via Telnet connection. For Telnet connection I use codes from Quick tool : A minimalistic Telnet library - CodeProject .
//create a new telnet connection to hostname "gobelijn" on port "23"
TelnetConnection tc = new TelnetConnection("gobelijn", 23);
//login with user "root",password "rootpassword", using a timeout of 100ms,
//and show server output
string s = tc.Login("root", "rootpassword",100);
Console.Write(s);
// server output should end with "$" or ">", otherwise the connection failed
string prompt = s.TrimEnd();
prompt = s.Substring(prompt.Length -1,1);
if (prompt != "$" && prompt != ">" )
throw new Exception("Connection failed");
prompt = "";
// while connected
while (tc.IsConnected && prompt.Trim() != "exit" )
{
// display server output
Console.Write(tc.Read());
// send client input to server
prompt = Console.ReadLine();
tc.WriteLine(prompt);
// display server output
Console.Write(tc.Read());
}
Console.WriteLine("***DISCONNECTED");
Console.ReadLine();
It worked for some simple one line-many parameter commands; like Settime [YYMMDD-HHmmss] that set time of the device. But When I want to execute a command like nsave that save changes in the device, command prompt of Telnet becomes like this:
>>nsave
Are you sure? (y/n)
I want to send y but I can’t.
Besides that, after each command I execute exit command to disconnect Telnet connection, but in this scenario (nsave) the connection will remain open and my program cannot connect to Telnet to execute further commands.
How can I include yes or other inputs in similar conditions?

Unable to connect to PostgreSQL server via SSH: No connection could be made because the target machine actively refused it

I am trying to automatically create an SSH connection for a program that uses an SSH tunnel to update a local database from a remote PostgreSQL server. Up to this time, I have been manually opening a tunnel with PuTTY (including local port forwarding instructions with the -L command). I want to use ssh.net to automatically open the port when the program is run. Once the connection is made, the program uses Entity Framework Core to access the remote database.
When I open the SSH connection with PuTTY, the program runs fine. This is the PuTTY command:
//plink.exe -i "C:\Users\user.name\Desktop\host_private_key.ppk" -L 6544:111.22.33.66:6543 -N user#address.io -pw *PASSWORD*"
(login details removed for privacy)
This is the ssh.net code that I have trying to open the same connection:
public void MakeSSHTunnel()
{
string password = "password";
// path of RSA private key in openSSH format:
string privateKeyPath = "C:/Users/user.name/.ssh/id_rsa";
try
{
// creates variable to transmit RSA private key + passphrase to server via SSH.NET, openSSH compatible.
var privateKeyFile = new PrivateKeyFile(privateKeyPath, password);
string serverAddress = "address.io";
string user = "user";
// allows for the remote port forwarding options required by the server
using (var client = new SshClient(serverAddress, user, privateKeyFile))
{
client.Connect();
var tunnel = new ForwardedPortLocal(6544, "111.22.33.66", 6543);
client.AddForwardedPort(tunnel);
// testing weather the connection has been successful:
if (client.IsConnected)
{
Console.WriteLine("OPENTUNNEL.CS: Connection to {0} successful.", serverAddress);
state = "Open";
}
else
{
Console.WriteLine("Connection to {0} failed.");
state = "Closed";
}
tunnel.Exception += delegate (object sender, ExceptionEventArgs e)
{
Console.WriteLine(e.Exception.ToString());
};
tunnel.Start();
Program.RunBackup();
// ... closes the port ... //
tunnel.Stop();
client.Disconnect();
}
}
catch (UnauthorizedAccessException e)
{
Console.WriteLine(e);
}
}
I am confused since in the above, the if (client.IsConnected) returns true.
The error seems to be occurring when the Entity Framework Core OnConfiguring() method passes details of the connection with its optionsBuilder:
optionsBuilder.UseNpgsql($"Host=127.0.0.1;Port=6544;Database=user;Username=user;Password=databasePassworh;CommandTimeout=300;Timeout=300;SSL Mode=Require;Trust Server Certificate=true;Convert Infinity DateTime=true");
The errors that are arising are:
NpgsqlException: Exception while connecting
and:
ExtendedSocketException: No connection could be made because the target machine actively refused it. 127.0.0.1:6544
I have double checked all passwords, and read through all the SSH.NET documentation and code examples, and left all the previously working (via PuTTY) code untouched.
If anyone can see what I'm doing wrong, I would be grateful. C#, SSH.NET and port forwarding are new to me, please tell me where I'm being an idiot.

This code is now working. I believe the problem was that in line:
var tunnel = new ForwardedPortLocal(6544, "111.22.33.66", 6543);
the 'bound port' did not include an address. I had seen examples where this was undefined, and had followed these. On stepping through the code, I noticed that the field was blank, and decided to try 127.0.0.1. This is now successfully connecting to the database. It works with:
var tunnel = new ForwardedPortLocal("127.0.0.1", 6544, "111.22.33.66", 6543);
Thanks for looking into this and for your contributions.

Use a new ssh connection using another established connection with SSH.NET [duplicate]

I am doing SSH to a Linux machine and again from there want to SSH to another Linux machine to carry out few Perforce tasks.
using (SshClient ssh = new SshClient("ip address","username", "pwd"))
{
ssh.Connect();
command = ssh.CreateCommand("ssh hostname");
result = command.Execute();
Console.WriteLine(result);
}
Where the ssh hostname is a password less ssh. How can I control the second SSH session and pass commands to it?
Even explored the CreateShell function, but seems like it is not suggested for automation.

In general, trying to automate ssh command is a bad design.
You better use a port forwarding (aka SSH tunnel) to implement the "hop".
var firstClient =
new SshClient(firstHostName, firstUserName, firstPassword);
firstClient.Connect();
var port = new ForwardedPortLocal("127.0.0.1", secondHostName, 22);
firstClient.AddForwardedPort(port);
port.Start();
var secondClient =
new SshClient(port.BoundHost, (int)port.BoundPort, secondUserName, secondPassword);
secondClient.Connect();
var command = secondClient.CreateCommand("ls");
var result = command.Execute();
Console.WriteLine(result);
There are some cases, when automating the ssh is acceptable (while still not ideal). E.g. because there's an authentication to the second host set up on the first one. I.e. there might be private key in the .ssh folder and you are not allowed to transfer that key to your client machine.
Even then, try talking to the system Administrator to find a better solution. The private key is still accessible using the credentials contained in your application, so it's not protected any better, had the private key itself been contained directly in the application.
Anyway, ssh can accept a command on its command line, like:
command = ssh.CreateCommand("ssh hostname command");
result = command.Execute();
Console.WriteLine(result);

Using SSH.NET to connect to Remote Hosts

I'm trying to automate configuring remote hosts, we have hundreds of these devices, we normally do it through USB programming, but if I could get a script to connect to these devices and do it programmatically, it would free up time.
These devices run some type of linux os, i'm not sure exactly, but they do have SSH enabled and confirm server host keys when you first connect to them via utility like PuTTY.
For now, i'm just trying to initiate an SSH session with the device. I've done quite a bit of research, and have come up with this:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Renci.SshNet;
using Renci.SshNet.Common;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
//Connection information
string user = "admin";
string pass = "********";
string host = "IP Address";
//Set up the SSH connection
using (var client = new SshClient(host, user, pass))
{
//Accept Host key
client.HostKeyReceived += delegate (object sender, HostKeyEventArgs e)
{
e.CanTrust = true;
};
//Start the connection
client.Connect();
var output = client.RunCommand("show device details");
client.Disconnect();
Console.WriteLine(output.ToString());
Console.ReadLine();
}
}
}
}
The problem is this doesn't seem to execute the command listed. The console window comes up, and I can access the same device by WebGUI and see the log file, it shows a connection being made, but when I break the execution and see the variable values the output variable shows null.
If I let the execution sit, with the console window open (just shows a blinking cursor in the upper left), the connection times out after 10 minutes and connection is lost, which I also see happen in the device log.
Why would does this not seem to execute the runcommand and store the results in the output variable?

When you execute the RunCommand() method on an object of type Renci.SshNet.SshClient, it does not return the result as a variable.
Instead, it returns an object of the Renci.SshNet.SshCommand type.
The issue is that, it looks like you can't fit this resultant SshCommand object into a var.
This Renci.SshNet.SshCommand, returned when you execute RunCommand(), will contain several properties and methods.
The properties are:
CommandText
CommandTimeout
ExitStatus
OutputStream
ExtendedOutputStream
Result
Error
They're all useful, but as everything else seems to be working, the only relevant one you want is "Result".
The "Result" property will contain a String, which will be the host stream result of the command you provided to RunCommand().
As you mention the device's logfile has logged a successful connection being made, it looks like the connection is successful. So you'd just have to make the proper tweak to grab the Result, as described above, and you should be good to go.
Addendum:
The following line in the original post's code:
var output = client.RunCommand("show device details");
Should be replaced with this code:
var output = client.RunCommand("show device details").Result;
This will assign the Result property (which is a String) to the output var, which will give the desired outcome.

SSH Connection via C#

This is the situation. I have a Windows machine and a Linux machine. There is a shared drive between these two machines (which is mapped to Q:). I am trying to figure out how to create an SSH session at the Q: drive (shared drive) from C#. I am trying to use the SharpSsh library to do this.
This is what I have so far, however, it is giving me an error:
try
{
ssh = new SshStream(host, username, password);
Console.WriteLine("OK ({0}/{1})", ssh.Cipher, ssh.Mac);
Console.WriteLine("Server version={0}, Client version={1}", ssh.ServerVersion, ssh.ClientVersion);
Console.WriteLine("-Use the 'exit' command to disconnect.");
Console.WriteLine();
//Sets the end of response character
ssh.Prompt = "#";
//Remove terminal emulation characters
ssh.RemoveTerminalEmulationCharacters = true;
//Reads the initial response from the SSH stream
Console.Write(ssh.ReadResponse()); // Blocking here
while (true)
{
string command = Console.ReadLine();
if (command.ToLower().Equals("exit"))
break;
//Write command to the SSH stream
ssh.Write(command);
//Read response from the SSH stream
Console.Write(ssh.ReadResponse());
}
}
catch(Exception e)
{
Console.WriteLine(e.Message);
}
if(ssh != null)
{
ssh.Close();
}
I have added the Tamir.SharpSSH.dll as a reference to the project, and I am using it in the project. There are two other dll's that are included with SharpSSH, do I need to add them as well to the references? The examples I have seen only have the Tamir.SharpSSH.dll as a reference.
I am not sure how to initiate the connection in the correct location, and how to submit commands properly to the ssh.
UPDATE
I realized I needed to close the SSH connection before ending the program. The error does not exist anymore, however, I am still not getting any information from my "ls" command.
UPDATE
I updated the code with what I have now. It seems like the ssh.ReadResponse() is blocking, which leads me to believe the server is not responding. Is that correct?