{"id":69410,"date":"2020-09-07T06:06:23","date_gmt":"2020-09-07T06:06:23","guid":{"rendered":"https:\/\/www.baeldung.com\/?p=86717"},"modified":"2020-09-07T06:06:23","modified_gmt":"2020-09-07T06:06:23","slug":"ssh-connection-with-java","status":"publish","type":"post","link":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/2020\/09\/07\/ssh-connection-with-java\/","title":{"rendered":"SSH Connection With Java"},"content":{"rendered":"

<\/p>\n

1. Introduction<\/h2>\n
<\/div>\n

SSH<\/a>, also known as Secure Shell or Secure Socket Shell, is a network protocol that allows one computer to securely connect to another computer<\/a> over an unsecured network. In this tutorial, we’ll show how to establish a connection to a remote SSH server with Java using the JSch and Apache MINA SSHD libraries<\/strong>.<\/p>\n

In our examples, we’ll first open the SSH connection, then execute one command, read the output and write it to the console, and, finally, close the SSH connection. We’ll keep the sample code as simple as possible.<\/p>\n

2. JSch<\/h2>\n
<\/div>\n

JSch<\/a> is the Java implementation of SSH2 that allows us to connect to an SSH server and use port forwarding, X11 forwarding, and file transfer. Also, it is licensed under the BSD style license and provides us with an easy way to establish an SSH connection with Java.<\/p>\n

First, let’s add the JSch Maven dependency<\/a> to our pom.xml<\/em> file:<\/p>\n

<dependency>\r\n    <groupId>com.jcraft<\/groupId>\r\n    <artifactId>jsch<\/artifactId>\r\n    <version>0.1.55<\/version>\r\n<\/dependency><\/code><\/pre>\n
2.1. Implementation<\/h3>\n
<\/div>\n
To establish an SSH connection using JSch, we need a username, password, host URL, and SSH port<\/strong>. The default SSH port is 22, but it could happen that we’ll configure the server to use other port for SSH connections:<\/p>\n
public static void listFolderStructure(String username, String password, \r\n  String host, int port, String command) throws Exception {\r\n    \r\n    Session session = null;\r\n    ChannelExec channel = null;\r\n    \r\n    try {\r\n        session = new JSch().getSession(username, host, port);\r\n        session.setPassword(password);\r\n        session.setConfig(\"StrictHostKeyChecking\", \"no\");\r\n        session.connect();\r\n        \r\n        channel = (ChannelExec) session.openChannel(\"exec\");\r\n        channel.setCommand(command);\r\n        ByteArrayOutputStream responseStream = new ByteArrayOutputStream();\r\n        channel.setOutputStream(responseStream);\r\n        channel.connect();\r\n        \r\n        while (channel.isConnected()) {\r\n            Thread.sleep(100);\r\n        }\r\n        \r\n        String responseString = new String(responseStream.toByteArray());\r\n        System.out.println(responseString);\r\n    } finally {\r\n        if (session != null) {\r\n            session.disconnect();\r\n        }\r\n        if (channel != null) {\r\n            channel.disconnect();\r\n        }\r\n    }\r\n}<\/code><\/pre>\n
As we can see in the code, we first create a client session and configure it for connection to our SSH server. Then, we create a client channel used to communicate with the SSH server where we provide a channel type – in this case, exec,<\/em> which means that we’ll be passing shell commands to the server.<\/p>\n
Also, we should set the output stream for our channel where the server response will be written. After we establish the connection using the\u00a0channel.connect()<\/em> method, the command is passed, and the received response is written on the console.<\/p>\n
Let’s see how to use different configuration parameters that JSch offers<\/strong>:<\/p>\n