Apache Camel SSH Component

December 2, 2013 - 6 minutes read - 1275 words

This article is about troubleshooting issues we have faced while using apache camel’s SSH routes. It also covers step wise guide to setup apache camel routes.

Prerequisites

Windows7
Eclipse Juno
Java 1.7

Problem Statement

We were getting following issues in the logs when connecting to one of the SSH server using Apache Camel-SSH. This was happening in one of the instance in production environment.

Here are few logs :

Server A :


Session created...
2013-11-28 18:12:44:855 | DEBUG [MSC service thread 1-15] Connected to 
2013-11-28 18:12:44:855 | DEBUG [MSC service thread 1-15] Attempting to authenticate username ******* using Password... 
2013-11-28 18:12:44:857 | INFO [NioProcessor-2] Server version string: SSH-2.0-SSHD-CORE-0.6.0
2013-11-28 18:12:45:165 | DEBUG [ClientInputStreamPump] Send SSH_MSG_CHANNEL_DATA on channel 0
2013-11-28 18:12:45:166 | DEBUG [ClientInputStreamPump] Send SSH_MSG_CHANNEL_EOF on channel 0
2013-11-28 18:12:45:178 | DEBUG [NioProcessor-2] Received packet SSH_MSG_CHANNEL_FAILURE
2013-11-28 18:12:45:178 | DEBUG [NioProcessor-2] Received SSH_MSG_CHANNEL_FAILURE on channel 0
2013-11-28 18:12:45:193 | DEBUG [NioProcessor-2] Closing session
2013-11-28 18:12:45:193 | DEBUG [NioProcessor-2] Closing channel 0
2013-11-28 18:12:45:193 | DEBUG [NioProcessor-2] Closing channel 0 immediately
2013-11-28 18:12:45:194 | DEBUG [NioProcessor-2] Closing IoSession
2013-11-28 18:12:45:194 | DEBUG [NioProcessor-2] IoSession closed
2013-11-28 18:12:45:195 | INFO [NioProcessor-2] Session ***@/***:** closed

Server B :

2013-11-29 13:53:09:280 | INFO [NioProcessor-2] Session created...
2013-11-29 13:53:09:297 | DEBUG [MSC service thread 1-13] Connected to 
2013-11-29 13:53:09:297 | DEBUG [MSC service thread 1-13] Attempting to authenticate username ***** using Password... 
2013-11-29 13:53:09:300 | INFO [NioProcessor-2] Server version string: SSH-2.0-OpenSSH_5.3
22013-11-29 13:53:09:472 | DEBUG [ClientInputStreamPump] Space available for client remote window
2013-11-29 13:53:09:472 | DEBUG [ClientInputStreamPump] Send SSH_MSG_CHANNEL_DATA on channel 0
2013-11-29 13:53:09:472 | DEBUG [ClientInputStreamPump] Send SSH_MSG_CHANNEL_EOF on channel 0
2013-11-29 13:53:09:494 | DEBUG [NioProcessor-2] Received packet SSH_MSG_CHANNEL_DATA
2013-11-29 13:53:09:494 | DEBUG [NioProcessor-2] Received SSH_MSG_CHANNEL_DATA on channel 0
2013-11-29 13:53:09:494 | DEBUG [NioProcessor-2] Received packet SSH_MSG_CHANNEL_EOF
2013-11-29 13:53:09:494 | DEBUG [NioProcessor-2] Received SSH_MSG_CHANNEL_EOF on channel 0
2013-11-29 13:53:09:495 | DEBUG [NioProcessor-2] Received packet SSH_MSG_CHANNEL_REQUEST
2013-11-29 13:53:09:495 | INFO [NioProcessor-2] Received SSH_MSG_CHANNEL_REQUEST on channel 0
2013-11-29 13:53:09:495 | DEBUG [NioProcessor-2] Received packet SSH_MSG_CHANNEL_CLOSE
2013-11-29 13:53:09:495 | DEBUG [NioProcessor-2] Received SSH_MSG_CHANNEL_CLOSE on channel 0
2013-11-29 13:53:09:495 | DEBUG [NioProcessor-2] Send SSH_MSG_CHANNEL_CLOSE on channel 0

Solving the Chaos!

We have taken following steps to resole the issues

Validate SSH - Checked SSH connection with putty and it was working fine, we were able to execute the commands.

Analyze Logs - SSH_MSG_CHANNEL_FAILURE error was coming on server A, but is working fine when trying to connect server B. We have noticed following logs

Server A:

2013-11-28 18:12:44:857 | INFO [NioProcessor-2] Server version string: SSH-2.0-SSHD-CORE-0.6.0

Server B:

 2013-11-29 13:53:09:300 | INFO [NioProcessor-2] Server version string: SSH-2.0-OpenSSH_5.3

So different SSH servers are being used.

Resolution 1 – Use same version of SSH Server

Install SSHD-CORE-0.6.0 on Server A /local system

Download http://mina.apache.org/sshd-project/download_0.6.0.html Extract download zip
Go to /bin
Run Server : Run sshd.bat(windows) or sshd.sh(linux)
Run Client: ssh.bat -l [loginuser] -p [port] [hostname] [command]
```
  ssh.bat -l login -p 8000 localhost
```
Enter password same as login name “login” It will open up the OS shell where you can run commands.
You can also try to connect ssh using Putty.exe on host and port.

So now our new SSH server is ready to use, but if we try to connect SSH as execution channel ssh.sh or ssh.bat with some command It always returns with

ssh.bat -l login -p 8000 localhost dir
Exception in thread "main" java.lang.IllegalArgumentException: command must not be null at org.apache.sshd.client.channel.ChannelExec.<init>(ChannelExec.java:35)
at org.apache.sshd.client.session.ClientSessionImpl.createExecChannel(ClientSessionImpl.java:175) at org.apache.sshd.client.session.ClientSessionImpl.createChannel(ClientSessionImpl.java:160)
at org.apache.sshd.client.session.ClientSessionImpl.createChannel(ClientSessionImpl.java:153)
at org.apache.sshd.SshClient.main(SshClient.java:402)
53352 [NioProcessor-2] INFO org.apache.sshd.client.session.ClientSessionImpl - Closing session

This is because the execution channel at client side is not well implemented. Only SCP command has been implemented. For now we can ignore this client error and try the camel example with new SSH server.

Try Camel-SSH with new SSH Server (SSHD-CORE)

Create Sample Camel-SSH Example

Create eclipse project using archetype “camel-archetype-spring"

mvn archetype:generate DarchetypeGroupId=com.tk.poc.camel -DarchetypeArtifactId=camel-archetype-spring - DarchetypeVersion=2.11.0 -DarchetypeRepository=https://repository.apache.org/content/groups/snapshots-group

Create following Java file

  package com.tk.poc.camel;

  import org.apache.camel.Endpoint;
  import org.apache.camel.Exchange;
  import org.apache.camel.Processor;
  import org.apache.camel.Producer;
  import org.apache.camel.builder.RouteBuilder; 
  import org.apache.camel.spring.Main;
  /**
  * A simple example router from a file system to an ActiveMQ queue and then to a file system *
  * @version
  */
  public class MyRouteBuilder extends RouteBuilder { 
    private static String source = "";
    private static String url = "";
  /**
   * Allow this route to be run as an application */
    public static void main(String[] args) throws Exception { 
      if (args.length > 0) {
          source = args[0];
          url = args[1]; }
          String[] ar = {};
          new Main().run(ar);
      }  
    public void configure() {
      from("file:" + source + "?noop=true&consumer.useFixedDelay=true&consumer.delay=60000").process(new Processor() { 
        public void process(Exchange exchange) throws Exception {
          Endpoint ePoint = exchange.getContext().getEndpoint(url); Producer producer = ePoint.createProducer(); producer.process(exchange);
        }  
      }).bean(new SomeBean());
    }  
    public static class SomeBean {   
      public void someMethod(String body) {
      System.out.println("Received: " + body); 
    }
  }
}

Pom.xml - dependencies

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-ssh</artifactId>
    <version>2.11.0</version>
    <!-- use the same version as your Camel core version -->
</dependency>

Clean up src/main/resources/META-INF/spring/camel-context.xml

<camel:camelContext xmlns="http://camel.apache.org/schema/spring">
   <camel:package>com.tk.poc.camel</camel:package>
</camel:camelContext>

Run mvn eclipse:eclipse to include dependencies in class path of eclipse.
```
mvn eclipse:eclipse
```
You can now directly run the MyRouteBuilder.java in eclipse with required argument
- Source – a folder path, where folder is containing a text file having command to execute on server.
- Camel URL for SSH component
```
 ssh://[username]@[host]?password=[password]&port=[port]
```
Let’s export the project as executable jars keeping the dependencies in separate folder

Lets create a run.bat

 java -jar ssh.jar "D:/TK/Testing/data" "ssh://login@localhost?password=login&port=8000"
 pause

Place the run.bat in the directory where jar has been exported.

Run the camel SSH example

Execute run.bat
We get same error as we see on production
So problem is now reproducible locally.

Resolution 2: Implement Exec channel support in SSH component

After looking at the component code, we found that only SCP command has been implemented, EXEC channel is not working correctly.

Extract as eclipse project

Download the camel-ssh source and import it as eclipse project
Update its pom.xml as follows

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>org.apache.camel</groupId>
	<artifactId>camel-ssh</artifactId>
	<packaging>jar</packaging>
	<version>2.11.0</version>
	<name>Camel :: SSH</name>
	<description>Camel SSH support</description>

	<properties>
		<camel.osgi.export.pkg>org.apache.camel.component.ssh.*</camel.osgi.export.pkg>
		<camel.osgi.export.service>org.apache.camel.spi.ComponentResolver;component=ssh</camel.osgi.export.service>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.apache.camel</groupId>
			<artifactId>camel-core</artifactId>
			<version>2.11.0</version>
		</dependency>

		<dependency>
			<groupId>org.apache.mina</groupId>
			<artifactId>mina-core</artifactId>
			<version>2.0.7</version>
		</dependency>
		<dependency>
			<groupId>org.apache.sshd</groupId>
			<artifactId>sshd-core</artifactId>
			<version>0.6.0</version>
		</dependency>

		<!-- test dependencies -->
		<dependency>
			<groupId>bouncycastle</groupId>
			<artifactId>bcprov-jdk15</artifactId>
			<version>140</version>
			<scope>compile</scope>
		</dependency>

		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-log4j12</artifactId>
			<scope>test</scope>
			<version>1.6.1</version>
		</dependency>
	</dependencies>
</project>

Update the component - Change the “SshEndpoint.java”

From :

public SshResult sendExecCommand(String command) throws Exception {
        SshResult result = null;
...
...
ClientChannel channel = session.createChannel(ClientChannel.CHANNEL_EXEC, command);

        ByteArrayInputStream in = new ByteArrayInputStream(new byte[]{0});
        channel.setIn(in);
...
...
}

To:

 public SshResult sendExecCommand(String command) throws Exception {
         SshResult result = null;
 ...
 ...
 ClientChannel channel = session.createChannel(ClientChannel.CHANNEL_SHELL);
 log.debug("Command : " + command);
 InputStream inputStream = new ByteArrayInputStream(command.getBytes());
 channel.setIn(inputStream);
 ...
 ...
 }

Build Again - Build the jar
```
mvn install
```

Try Camel-SSH Again

Use updated jar - Rebuild Camel SSH example or place the camel-ssh-2.11.0.jar in the ssh_lib folder.
Specify Shell Termination command

/data/command.txt
```
ls
exit
```

Execute Run.bat

It returns the result of command on server

SH_MSG_CHANNEL_EXTENDED_DATA on channel 0
[                NioProcessor-2] ClientSessionImpl              DEBUG Received packet SSH_MSG_CHANNEL_EOF
[                NioProcessor-2] ChannelShell                   INFO  Received SSH_MSG_CHANNEL_EOF on channel 0
[                NioProcessor-2] ClientSessionImpl              DEBUG Received packet SSH_MSG_CHANNEL_REQUEST
[                NioProcessor-2] ChannelShell                   INFO  Received SSH_MSG_CHANNEL_REQUEST on channel 0
[                NioProcessor-2] ClientSessionImpl              DEBUG Received packet SSH_MSG_CHANNEL_CLOSE
[                NioProcessor-2] ChannelShell                   INFO  Received SSH_MSG_CHANNEL_CLOSE on channel 0
[                NioProcessor-2] ChannelShell                   INFO  Send SSH_MSG_CHANNEL_CLOSE on channel 0
Received: 2
anaconda-ks.cfg
key.pem
Kuldeep
logfile
Music
nohup.out
Videos

Another Issue on Server

We have faced issue that channel is not being closed and following log is being printing

Resolution 3: Identify the termination command on Shell

We need to identify the termination command for the shell on server, we noticed that termination command on server’s default shell was “exit;” instead of “exit”. We updated /data/command.txt accordingly, /data/command.txt

  ls
  exit;

and things worked for us.

So here you have customized Apache Camel component.

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