Timeout on sshClient.RunCommand C#

Question

I have a C# code in which I am executing on Visual Studio 2017. My aim is to start multiple threads in parallel and connect to different IPs via SSH, execute a command on these devices and return the output to the Console. An example of connecting to one such device with IP: 192.168.46.126 is as follows:

Thread myNewThread = new Thread(() => sendCommand("192.168.46.126", command));
myNewThread.Start();

The sendCommand function is as follows:

void sendCommand(string IPaddr, string command)
{
    using (var sshClient = new SshClient(IPaddr, username, password))
    {
        sshClient.Connect();
        sshClient.Runcommand(command); //Takes a lot of time to execute
    }
}

The sshClient.runCommand(command) takes a lot of time to execute. I need to run all these threads in parallel to connect to each device and print their statuses to the Console. In case a thread takes too long, I need to have a timeout option. I searched online but their seems to be no timeout option on the RunCommand function. The only timeout option seems to be on the connect() function implemented via following code:

client.ConnectionInfo.Timeout = TimeSpan.FromSeconds(10);

Is their a way I can implemet a timout for the runCommand line of code?

Instead of RunCommand use CreateCommand that will return an SshCommand instance. You can then set a timeout on that instance and execute the command from that instance. Haven't tried myself, my explanation is based on looking at the source code of the SshClient... (general advice: if you use a library and documentation is lacking, first look at all the methods/properties/fields provided by a class you want to use. If that is not revealing enough and the library is open source, take a gander at the source code. It is often rather easy to figure out how to do things this way...) — user2819245
– user2819245, Commented Feb 19, 2019 at 20:44

Ivan Plascencia · Accepted Answer · 2021-01-14 23:35:52Z

@user2819245 is correct. I had the same problem so I change my code to use CreateCommand(), defining the CommandTimeout and then invoking Execute(). Note: A try/catch is necessary around the Execute() to catch SshOperationTimeoutException. I had expected the command Result and/or Error would have been used to capture the timeout error, but alas it is not.

Here is how your code should have been updated to

void sendCommand(string IPaddr, string command)
{
    using (var sshClient = new SshClient(IPaddr, username, password))
    {
        sshClient.Connect();
        Renci.SshNet.SshCommand command = sshClient.CreateCommand(command);
        command.CommandTimeout = TimeSpan.FromSeconds(10); // 10sec timeout

        try
        {
            command.Execute();
        }
        catch (Renci.SshNet.Common.SshOperationTimeoutException)
        {
            // however you want to handle it
        } 

        client.Disconnect();      
    }
}

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