Ganymed SSH2 Cisco Router | Using Ganymed SSH2 to Configure Cisco Routes/Switches

Configure Cisco Routers/Switches Using SSH

I have some use cases where SSH is used to configure Cisco routers/switches. For example, to enable a WAN interface, the following commands are executed:

en
password
configure terminal 
int Fa0/0/0
ip address 172.0.0.1255.255.255.252
description Link to 408
bandwidth 8000
service-policy output shape-8Mb
no shutdown
end

copy run start
exit

 

Apache Camel SSH Component

Apache Camel has a SSH component. However, I found that it did not work when configuring Cisco routers/switches.
The problem is that it cannot execute the "en password" command.

Ganymed SSH2 Library

Fortunately I could solve it by using another SSH library called Ganymed.
The following is the code I used to execute IOS commands.

 

private static final String PROMPT_SYMBOL = "%";
private static final char ERROR_SYMBOL = '^';
private static final String ACCESS_DENIED_MESSAGE = "Access denied";
private static final int MAX_OUTPUT_BUFFER_SIZE = 1024 * 1024;

public void executeCommand(String host, String username, String password, int timeout, String command) throws IOException, AccessDeniedException
{
  Connection connection = new Connection(host);
  
  connection.connect(null, timeout, timeout);
  
  boolean authenticated = connection.authenticateWithPassword(username, password);
  
  if (!authenticated)
    return;
  
  Session session = connection.openSession();
  session.startShell();
  
  executeCommand(session, timeout, command);
}
 

private SshResponse executeCommand(Session session, int timeout, String command) throws IOException, AccessDeniedException
{
  OutputStream in = session.getStdin();

  in.write(command.getBytes());
  
  InputStream stdout = session.getStdout();
  InputStream stderr = session.getStderr();
  
  StringBuilder sb = new StringBuilder();
  boolean valid = false;
  String line = null;

  boolean flag = true;
  while (flag)
  {
    int conditions = session.waitForCondition(ChannelCondition.STDOUT_DATA | ChannelCondition.STDERR_DATA | ChannelCondition.EOF, timeout);

    if ((conditions & ChannelCondition.TIMEOUT) != 0)
    {
      break;
    }

    if ((conditions & ChannelCondition.EOF) != 0)
    {
      if ((conditions & (ChannelCondition.STDOUT_DATA | ChannelCondition.STDERR_DATA)) == 0)
      {
        break;
      }
    }

    BufferedReader reader = null;
    try
    {
      if ((ChannelCondition.STDOUT_DATA & conditions) != 0)
      {
        reader = new BufferedReader(new InputStreamReader(stdout));
      }
      else
      {
        reader = new BufferedReader(new InputStreamReader(stderr));
      }

      //Reader.readLine() may hang if 'exit' is not added to the command as the last line (use the 'exit' to exit the shell)
      
      boolean toAppend = true;
      
      while (true)
      {
        line = reader.readLine();
        
        if (line == null)
        {
          valid = true;
          
          flag = false;
          break;
        }
        
        if (toAppend)
        {
          toAppend = this.append(sb, line);
        }
        
        if (line.trim().startsWith(PROMPT_SYMBOL))
        {
          if (line.trim().indexOf(ERROR_SYMBOL) >= 0)
          {
            valid = false;
            
            flag = false;
            break;
          }
          else if (line.trim().contains(ACCESS_DENIED_MESSAGE))
          {
            throw new AccessDeniedException(line.trim());
          }
        }
        
        line = reader.readLine();
      }
    }
    finally
    {
      if (reader != null)
        reader.close();
    }
  }
  
  String message = sb.toString().trim();
  
  SshResponse response = new SshResponse();
  
  response.setCommand(command);
  response.setValid(valid);
  response.setOut(message);
  //keep all output
  //r4(config)#int Fastethernet1/0
  //               ^
  //% Invalid input detected at '^' marker.
  response.setErr(message);
  
  return response;
}
private boolean append(StringBuilder sb, String line)
{
  if (sb.length() >= MAX_OUTPUT_BUFFER_SIZE)
  {
    sb.setLength(MAX_OUTPUT_BUFFER_SIZE - 3);
    sb.append("...");
    
    return false;
  }
  
  if (sb.length() + line.length() > MAX_OUTPUT_BUFFER_SIZE)
  {
    //Minimum abbreviation width is 4
    if (MAX_OUTPUT_BUFFER_SIZE - sb.length() < 4)
    {
      sb.setLength(MAX_OUTPUT_BUFFER_SIZE - 3);
      sb.append("...");
    }
    else
    {
      String abbreviated = StringUtils.abbreviate(line, MAX_OUTPUT_BUFFER_SIZE - sb.length());
      
      sb.append(abbreviated);
    }
    
    sb.append('\n');
    
    return false;
  }
  
  sb.append(line);
  sb.append('\n');
  
  return true;
}

Keep in mind that the last command "exit" should not be omitted otherwise the SSH session may hang up for ever.