通过ssh.net在每个命令上进行双因素验证

Question

通过ssh.net在每个命令上进行双因素验证

3

我正在使用以下代码通过SSH.NET连接到Unix服务器：

ssh = new SshClient("myserver.univ.edu", Username, Password);
ssh.Connect();

The connection goes through and appears to generate no exception. The server is set up to require two factor authentication, but I get no prompt on my phone (using that as physical authenticator/OTP device). But the connection seems to be ok.

I then issue a command with this code:

SshCommand NewLookup = ssh.CreateCommand("newlookup " + IpNameOrAddress.Text))
LogText.Text += NewLookup.Execute().Replace("\n", Environment.NewLine);

And then I get the push to my phone (2nd factor verification request). Once I accept the verification request through the phone, then the command executes just fine. This would be all ok, except that...

Problem

I get a push to my phone for every subsequent command, so if I want to use that connection to run multiple commands, I have to sit on my phone clicking "Accept" for every command. So, how do I avoid getting a push on every command?

- user4843530

什么是空闲时间？指令之间有多长时间间隔？ - BOB

1

@Jeremiah - 几秒钟不到5秒，我已经将连接超时时间增加到60秒。不过你的想法很好。 - user4843530

我刚刚将连接超时时间增加到15分钟，但没有任何效果。 - user4843530

1

问题在于您正在使用ssh中的命令通道发送命令，这与shell会话不同。虽然通常不建议这样做，但我认为您需要考虑改用ShellStream来发送命令。 - NetMage

@NetMage - 是的，这正是我所想的，但由于有关ShellStream不被推荐使用的所有警告，我不愿意去那里。请将其作为答案，并在不久后如果我没有得到其他答案，我会接受它。 - user4843530

1个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- NetMage · Accepted Answer

为了在单个会话中使用SSH.NET发送多个命令，您可能需要使用ShellStream。这应该将您的2FA批准减少到仅打开到主机的会话。这对于不支持命令通道但支持SSH远程终端（例如您可以putty到它们）的设备（如HPE交换机）以及命令更改（shell）环境并因此需要保持会话打开以完成任务的情况也很有用。否则，SSH命令通道是处理此问题的预期（且更好的）方式。

您可以在NuDoc - SSH.NET上找到更多SSH.NET文档，而SSH.Net项目的GitHub版本包括Windows帮助文件。

以下是我编写的一些代码，用于包装ShellStream，并保留StreamReader和StreamWriter，处理从（HP）交换机读取输入并过滤出转义序列，以及读取下一个提示：

public static class SshClientExt {
    public static ExtShellStream CreateExtShellStream(this SshClient sc, string termName, uint rows, uint cols, uint width, uint height, int bufSize) =>
        new ExtShellStream(sc.CreateShellStream(termName, rows, cols, width, height, bufSize));
}

public class ExtShellStream : IDisposable {
    static Regex reEscVT100 = new Regex("\x1B\\[[^A-Z]+[A-Z]", RegexOptions.Compiled);
    static TimeSpan ReadTimeout = new TimeSpan(0, 0, 10);

    ShellStream ssh;
    StreamReader sr;
    StreamWriter sw;

    public ExtShellStream(ShellStream anSSH) {
        ssh = anSSH;
        sr = new StreamReader(ssh);
        sw = new StreamWriter(ssh);
    }

    public List<string> ReadLines() {
        // try to read all in
        long prev;
        do {
            prev = ssh.Length;
            Thread.Sleep(250);
        } while (ssh.Length != prev);

        "-".Repeat(40).Dump();
        var ans = new List<string>();

        while (true) {
            var line = sr.ReadLine();
            if (line != null) {
                line = line.Remove(reEscVT100).TrimEnd();
                $@"""{line}""".Dump();
                if (line.EndsWith("#")) // stop when prompt appears
                    break;
                else
                    ans.Add(line);
            }
            else
                Thread.Sleep(500);
        }

        return ans;
    }

    public void DumpLines() => ReadLines();

    public List<string> DoCommand(string cmd) {
        sw.Write(cmd);
        sw.Write("\r");
        sw.Flush();
        while (!ssh.DataAvailable)
            Thread.Sleep(500);
        return ReadLines().SkipWhile(l => l == cmd).ToList();
    }

    #region IDisposable Support
    private bool disposedValue = false; // To detect redundant calls

    protected virtual void Dispose(bool disposing) {
        if (!disposedValue) {
            if (disposing) {
                // prevent double dispose
                // don't dispose of sr or sw: only disposable resource is ssh
                ssh.Dispose();
            }

            disposedValue = true;
        }
    }

    // This code added to correctly implement the disposable pattern.
    public void Dispose() {
        // Do not change this code. Put cleanup code in Dispose(bool disposing) above.
        Dispose(true);
    }
    #endregion

}

下面是一个使用SSH.Net代码实现从交换机中检索配置信息的示例函数：

public static void RetrieveConfigFiles(IDFStack idf) {
    using (var sshClient = new SshClient(idf.IPAddress, username, password)) {
        sshClient.Connect();

        using (var ssh = sshClient.CreateExtShellStream("dumb", 120, 80, 0, 0, 200000)) {
            ssh.DumpLines();
            ssh.DoCommand("no page");

            File.WriteAllLines(idf.ConfigPath, ssh.DoCommand("show running-config structured"));
            File.WriteAllLines(idf.StatusPath, ssh.DoCommand("show interfaces brief"));
            File.WriteAllLines(idf.LLDPPath, ssh.DoCommand("show lldp info remote-device detail"));
        }

        sshClient.Disconnect();
    }
}