Rebex Terminal Emulation

Terminal emulation, SSH Shell and Telnet component for .NET

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Communication logging and replay

Session recording and replaying 

TerminalControl and VirtualTerminal classes have a useful and unique feature - session recording. This makes it possible to save a complete SSH shell session into a file and replay it later using our ANSI Player application.

// start recording the session to a file
terminal.Recorder = System.IO.File.AppendText("recording.ans");

// the resulting file can be replayed by the AnsiPlayer sample
' start recording the session to a file
terminal.Recorder = System.IO.File.AppendText("recording.ans")

' the resulting file can be replayed by the AnsiPlayer sample

Tip: ANSI Player sample comes with source code and can be easily embedded into your application.

Logging communication using LogWriter 

Communication logs are very useful when troubleshooting issues at the SSH protocol or communication level. Whenever you run into a problem, a log makes it possible to see what is going on.

To start logging, just add the following line into your code (just after creating the Ssh object):

// create an SSH object
var ssh = new Rebex.Net.Ssh();

// start logging to a file
ssh.LogWriter = new Rebex.FileLogWriter(@"C:\MyData\log.txt");
' create an SSH object
Dim ssh = New Rebex.Net.Ssh()

' start logging to a file
ssh.LogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt")

A sample log file:

2013-03-13 11:06:23.188 Opening log file.
2013-03-13 11:06:23.189 Using FileLogWriter version 2.0.2700.0.
2013-03-13 11:06:23.193 INFO Ssh(4)[34] Info: Connecting to testserver.local:22 using Ssh 1.0.2700.0.
2013-03-13 11:06:23.203 INFO Ssh(4)[34] SSH: Negotiation started.
2013-03-13 11:06:23.243 INFO Ssh(4)[34] SSH: Negotiation finished.
2013-03-13 11:06:23.243 INFO Ssh(4)[34] Info: Server: SSH-2.0-OpenSSH_6.0p1 Debian-3
2013-03-13 11:06:23.243 INFO Ssh(4)[34] Info: Fingerprint: e2:29:05:cd:7a:59:ee:03:fa:03:f5:72:61:77:e3:1c
2013-03-13 11:06:23.244 INFO Ssh(4)[34] Info: Cipher info: SSH 2.0, DiffieHellmanGroupExchangeSHA256, DSS, aes256-ctr/aes256-ctr

Log verbosity levels 

There are several levels of log verbosity:

  • Error - logs error messages only
  • Info - default level; logs important informative messages as well
  • Debug - logs all messages useful for debugging purposes
  • Verbose - very detailed log for advanced analysis; logs content of communication packets
    Warning: At the Verbose level, user credentials are written to the log as well.

To specify a log level, just pass an argument to FileLogWriter's constructor:

// start logging to a file at debug level
ssh.LogWriter = new Rebex.FileLogWriter(
    @"C:\MyData\log.txt", Rebex.LogLevel.Debug);
' start logging to a file at debug level
ssh.LogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt", Rebex.LogLevel.Debug)

Built-in log writers 

Text file

To log into a text file, use FileLogWriter:

// start logging to a file at debug level
ssh.LogWriter = new Rebex.FileLogWriter(
    @"C:\MyData\log.txt", Rebex.LogLevel.Debug);
' start logging to a file at debug level
ssh.LogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt", Rebex.LogLevel.Debug)

.NET trace listener

To log to .NET Trace Listeners, use TraceLogWriter:

// start logging to subscribed trace listeners
ssh.LogWriter = new Rebex.TraceLogWriter(Rebex.LogLevel.Debug);
' start logging to subscribed trace listeners
ssh.LogWriter = New Rebex.TraceLogWriter(Rebex.LogLevel.Debug)

Standard output stream

To log to the standard output stream, use ConsoleLogWriter:

// start logging to the standard output stream at debug level
ssh.LogWriter = new Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug);
' start logging to the standard output stream at debug level
ssh.LogWriter = New Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug)

Logging to multiple log writers

To log to more log writers at the same time, use TeeLogWriter:

var consoleLogWriter = new Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug);
var fileLogWriter = new Rebex.FileLogWriter(@"C:\MyData\log.txt", Rebex.LogLevel.Info);

// start logging to both console and file log writers
ssh.LogWriter = new Rebex.TeeLogWriter(consoleLogWriter, fileLogWriter);
Dim consoleLogWriter = New Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug)
Dim fileLogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt", Rebex.LogLevel.Debug)

' start logging to both console and file log writers
ssh.LogWriter = New Rebex.TeeLogWriter(consoleLogWriter, fileLogWriter)

Writing custom log writers 

To implement your own LogWriter, either implement Rebex.ILogWriter interface or simply derive a class from Rebex.LogWriterBase:
// Sample log writer that logs to the standard error output stream
public class MyLogWriter : LogWriterBase
{
    protected override void WriteMessage(string message)
    {
        Console.Error.WriteLine("Rebex: {0}", message);
    }
}
' Sample log writer that logs to the standard error output stream
Public Class MyLogWriter
    Inherits LogWriterBase

    Protected Overrides Sub WriteMessage(message As String)
        Console.Error.WriteLine("Rebex: {0}", message)
    End Sub

End Class