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• Command To Generate Ssh Key In Hadoop Data
• Hadoop Basic Commands
• Command To Generate Ssh Key In Hadoop Download
• Hadoop Commands Tutorial

With a secure shell (SSH) key pair, you can create virtual machines (VMs) in Azure that use SSH keys for authentication, eliminating the need for passwords to sign in. This article shows you how to quickly generate and use an SSH public-private key file pair for Linux VMs. You can complete these steps with the Azure Cloud Shell, a macOS or Linux host, the Windows Subsystem for Linux, and other tools that support OpenSSH.

Note

VMs created using SSH keys are by default configured with passwords disabled, which greatly increases the difficulty of brute-force guessing attacks.

Command To Generate Ssh Key In Hadoop Data

##Create an SSH key. Use the following information if you plan on using SSH keys with your cluster. If you plan on using a password, you can skip this section. Open a terminal session and use the following command to see if you have any existing SSH keys: ls -al /.ssh Look.

1. It needs to include encryption ('k9') in the filename in order to create an RSA key and enable ssh.
2. Jan 30, 2018  Installing Hadoop on Ubuntu Linux (Single Node Cluster) Now a days, Bigdata is a buzzword, The prominent technology behind this jargon is Hadoop. It is a good to have skill in developer’s resume. In order to learn Hadoop, it is mandatory to have a single node Hadoop cluster ready to play with Hadoop.
3. To create an SSH connection authenticated with a private key file, you need to specify the Amazon EC2 key pair private key when you launch a cluster. If you launch a cluster from the console, the Amazon EC2 key pair private key is specified in the Security and Access section on the Create Cluster page.
4. Apr 20, 2010  Now login (as the hadoop user) to your slave machine. While on your slave machine add your master machine’s hadoop user’s public key to the slave machine’s hadoop authorized key store. $ cat /.ssh/master.pub /.ssh/authorizedkeys Now, from the master node try to ssh to slave.

For more background and examples, see Detailed steps to create SSH key pairs.

For additional ways to generate and use SSH keys on a Windows computer, see How to use SSH keys with Windows on Azure.

Supported SSH key formats

Azure currently supports SSH protocol 2 (SSH-2) RSA public-private key pairs with a minimum length of 2048 bits. Other key formats such as ED25519 and ECDSA are not supported.

Create an SSH key pair

Use the ssh-keygen command to generate SSH public and private key files. By default, these files are created in the ~/.ssh directory. You can specify a different location, and an optional password (passphrase) to access the private key file. If an SSH key pair with the same name exists in the given location, those files are overwritten.

The following command creates an SSH key pair using RSA encryption and a bit length of 4096:

If you use the Azure CLI to create your VM with the az vm create command, you can optionally generate SSH public and private key files using the --generate-ssh-keys option. The key files are stored in the ~/.ssh directory unless specified otherwise with the --ssh-dest-key-path option. The --generate-ssh-keys option will not overwrite existing key files, instead returning an error. In the following command, replace VMname and RGname with your own values:

Provide an SSH public key when deploying a VM

To create a Linux VM that uses SSH keys for authentication, specify your SSH public key when creating the VM using the Azure portal, Azure CLI, Azure Resource Manager templates, or other methods:

If you're not familiar with the format of an SSH public key, you can display your public key with the following cat command, replacing ~/.ssh/id_rsa.pub with the path and filename of your own public key file if needed:

A typical public key value looks like this example:

If you copy and paste the contents of the public key file to use in the Azure portal or a Resource Manager template, make sure you don't copy any trailing whitespace. To copy a public key in macOS, you can pipe the public key file to pbcopy. Similarly in Linux, you can pipe the public key file to programs such as xclip.

The public key that you place on your Linux VM in Azure is by default stored in ~/.ssh/id_rsa.pub, unless you specified a different location when you created the key pair. To use the Azure CLI 2.0 to create your VM with an existing public key, specify the value and optionally the location of this public key using the az vm create command with the --ssh-key-values option. In the following command, replace VMname, RGname, and keyFile with your own values:

If you want to use multiple SSH keys with your VM, you can enter them in a space-separated list, like this --ssh-key-values sshkey-desktop.pub sshkey-laptop.pub.

SSH into your VM

With the public key deployed on your Azure VM, and the private key on your local system, SSH into your VM using the IP address or DNS name of your VM. In the following command, replace azureuser and myvm.westus.cloudapp.azure.com with the administrator user name and the fully qualified domain name (or IP address):

If you specified a passphrase when you created your key pair, enter that passphrase when prompted during the login process. The VM is added to your ~/.ssh/known_hosts file, and you won't be asked to connect again until either the public key on your Azure VM changes or the server name is removed from ~/.ssh/known_hosts.

If the VM is using the just-in-time access policy, you need to request access before you can connect to the VM. For more information about the just-in-time policy, see Manage virtual machine access using the just in time policy.

Next steps

• For more information on working with SSH key pairs, see Detailed steps to create and manage SSH key pairs.

• If you have difficulties with SSH connections to Azure VMs, see Troubleshoot SSH connections to an Azure Linux VM.

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Learn how to use Secure Shell (SSH) to securely connect to Apache Hadoop on Azure HDInsight. For information on connecting through a virtual network, see Azure HDInsight virtual network architecture and Plan a virtual network deployment for Azure HDInsight clusters.

The following table contains the address and port information needed when connecting to HDInsight using an SSH client:

Address	Port	Connects to..
<clustername>-ssh.azurehdinsight.net	22	Primary headnode
<clustername>-ssh.azurehdinsight.net	23	Secondary headnode
<clustername>-ed-ssh.azurehdinsight.net	22	edge node (ML Services on HDInsight)
<edgenodename>.<clustername>-ssh.azurehdinsight.net	22	edge node (any other cluster type, if an edge node exists)

Replace <clustername> with the name of your cluster. Replace <edgenodename> with the name of the edge node.

If your cluster contains an edge node, we recommend that you always connect to the edge node using SSH. The head nodes host services that are critical to the health of Hadoop. The edge node runs only what you put on it. For more information on using edge nodes, see Use edge nodes in HDInsight. /mac-generate-ssh-key-for-gitlab.html.

Tip

When you first connect to HDInsight, your SSH client may display a warning that the authenticity of the host can't be established. When prompted select 'yes' to add the host to your SSH client's trusted server list.

If you have previously connected to a server with the same name, you may receive a warning that the stored host key does not match the host key of the server. Consult the documentation for your SSH client on how to remove the existing entry for the server name.

SSH clients

Linux, Unix, and macOS systems provide the ssh and scp commands. The ssh client is commonly used to create a remote command-line session with a Linux or Unix-based system. The scp client is used to securely copy files between your client and the remote system.

Microsoft Windows doesn't install any SSH clients by default. The ssh and scp clients are available for Windows through the following packages:

• OpenSSH Client. This client is an optional feature introduced in the Windows 10 Fall Creators Update.

• Bash on Ubuntu on Windows 10.

• Azure Cloud Shell. The Cloud Shell provides a Bash environment in your browser.

• Git.

There are also several graphical SSH clients, such as PuTTY and MobaXterm. While these clients can be used to connect to HDInsight, the process of connecting is different than using the ssh utility. For more information, see the documentation of the graphical client you're using.

Authentication: SSH Keys

SSH keys use public-key cryptography to authenticate SSH sessions. SSH keys are more secure than passwords, and provide an easy way to secure access to your Hadoop cluster.

If your SSH account is secured using a key, the client must provide the matching private key when you connect:

• Most clients can be configured to use a default key. For example, the ssh client looks for a private key at ~/.ssh/id_rsa on Linux and Unix environments.

• You can specify the path to a private key. With the ssh client, the -i parameter is used to specify the path to private key. For example, ssh -i ~/.ssh/id_rsa sshuser@myedge.mycluster-ssh.azurehdinsight.net.

• If you have multiple private keys for use with different servers, consider using a utility such as ssh-agent (https://en.wikipedia.org/wiki/Ssh-agent). The ssh-agent utility can be used to automatically select the key to use when establishing an SSH session.

Important

If you secure your private key with a passphrase, you must enter the passphrase when using the key. Utilities such as ssh-agent can cache the password for your convenience.

Create an SSH key pair

Use the ssh-keygen command to create public and private key files. The following command generates a 2048-bit RSA key pair that can be used with HDInsight:

You're prompted for information during the key creation process. For example, where the keys are stored or whether to use a passphrase. After the process completes, two files are created; a public key and a private key.

• The public key is used to create an HDInsight cluster. The public key has an extension of .pub.

• The private key is used to authenticate your client to the HDInsight cluster.

Important

You can secure your keys using a passphrase. A passphrase is effectively a password on your private key. Even if someone obtains your private key, they must have the passphrase to use the key.

Create HDInsight using the public key

Creation method	How to use the public key
Azure portal	Uncheck Use cluster login password for SSH, and then select Public Key as the SSH authentication type. Finally, select the public key file or paste the text contents of the file in the SSH public key field.
Azure PowerShell	Use the -SshPublicKey parameter of the New-AzHdinsightCluster cmdlet and pass the contents of the public key as a string.
Azure CLI	Use the --sshPublicKey parameter of the az hdinsight create command and pass the contents of the public key as a string.
Resource Manager Template	For an example of using SSH keys with a template, see Deploy HDInsight on Linux with SSH key. The publicKeys element in the azuredeploy.json file is used to pass the keys to Azure when creating the cluster.

Authentication: Password

SSH accounts can be secured using a password. When you connect to HDInsight using SSH, you're prompted to enter the password.

Warning

Microsoft does not recommend using password authentication for SSH. Passwords can be guessed and are vulnerable to brute force attacks. Instead, we recommend that you use SSH keys for authentication.

Important

The SSH account password expires 70 days after the HDInsight cluster is created. If your password expires, you can change it using the information in the Manage HDInsight document.

Create HDInsight using a password

Creation method	How to specify the password
Azure portal	By default, the SSH user account has the same password as the cluster login account. To use a different password, uncheck Use cluster login password for SSH, and then enter the password in the SSH password field.
Azure PowerShell	Use the --SshCredential parameter of the New-AzHdinsightCluster cmdlet and pass a PSCredential object that contains the SSH user account name and password.
Azure CLI	Use the --ssh-password parameter of the az hdinsight create command and provide the password value.
Resource Manager Template	For an example of using a password with a template, see Deploy HDInsight on Linux with SSH password. The linuxOperatingSystemProfile element in the azuredeploy.json file is used to pass the SSH account name and password to Azure when creating the cluster.

Change the SSH password

For information on changing the SSH user account password, see the Change passwords section of the Manage HDInsight document.

Authentication domain joined HDInsight

If you're using a domain-joined HDInsight cluster, you must use the kinit command after connecting with SSH local user. This command prompts you for a domain user and password, and authenticates your session with the Azure Active Directory domain associated with the cluster.

You can also enable Kerberos Authentication on each domain joined node (for example, head node, edge node) to ssh using the domain account. To do this edit sshd config file:

uncomment and change KerberosAuthentication to yes

Use klist command to verify whether the Kerberos authentication was successful.

For more information, see Configure domain-joined HDInsight.

Connect to nodes

The head nodes and edge node (if there's one) can be accessed over the internet on ports 22 and 23.

• When connecting to the head nodes, use port 22 to connect to the primary head node and port 23 to connect to the secondary head node. The fully qualified domain name to use is clustername-ssh.azurehdinsight.net, where clustername is the name of your cluster.

• When connecting to the edge node, use port 22. The fully qualified domain name is edgenodename.clustername-ssh.azurehdinsight.net, where edgenodename is a name you provided when creating the edge node. clustername is the name of the cluster.

Important

The previous examples assume that you are using password authentication, or that certificate authentication is occurring automatically. If you use an SSH key-pair for authentication, and the certificate is not used automatically, use the -i parameter to specify the private key. For example, ssh -i ~/.ssh/mykey sshuser@clustername-ssh.azurehdinsight.net.

Once connected, the prompt changes to indicate the SSH user name and the node you're connected to. For example, when connected to the primary head node as sshuser, the prompt is sshuser@<active-headnode-name>:~$.

Connect to worker and Apache Zookeeper nodes

The worker nodes and Zookeeper nodes aren't directly accessible from the internet. They can be accessed from the cluster head nodes or edge nodes. The following are the general steps to connect to other nodes:

1. Use SSH to connect to a head or edge node:

2. From the SSH connection to the head or edge node, use the ssh command to connect to a worker node in the cluster:

   To retrieve a list of the node names, see the Manage HDInsight by using the Apache Ambari REST API document.

If the SSH account is secured using a password, enter the password when connecting.

If the SSH account is secured using SSH keys, make sure that SSH forwarding is enabled on the client.

Note

Another way to directly access all nodes in the cluster is to install HDInsight into an Azure Virtual Network. Then, you can join your remote machine to the same virtual network and directly access all nodes in the cluster.

For more information, see Plan a virtual network for HDInsight.

Configure SSH agent forwarding

Important

The following steps assume a Linux or UNIX-based system, and work with Bash on Windows 10. If these steps do not work for your system, you may need to consult the documentation for your SSH client.

1. Using a text editor, open ~/.ssh/config. If this file doesn't exist, you can create it by entering touch ~/.ssh/config at a command line.

2. Add the following text to the config file.

   Replace the Host information with the address of the node you connect to using SSH. The previous example uses the edge node. This entry configures SSH agent forwarding for the specified node.

3. Test SSH agent forwarding by using the following command from the terminal:

   This command returns information similar to the following text:

   If nothing is returned, then ssh-agent isn't running. For more information, see the agent startup scripts information at Using ssh-agent with ssh (http://mah.everybody.org/docs/ssh) or consult your SSH client documentation.

4. Once you've verified that ssh-agent is running, use the following to add your SSH private key to the agent:

   If your private key is stored in a different file, replace ~/.ssh/id_rsa with the path to the file.

5. Connect to the cluster edge node or head nodes using SSH. Then use the SSH command to connect to a worker or zookeeper node. The connection is established using the forwarded key.

Copy files

The scp utility can be used to copy files to and from individual nodes in the cluster. For example, the following command copies the test.txt directory from the local system to the primary head node: /internet-download-manager-key-generator.html.

Since no path is specified after the :, the file is placed in the sshuser home directory.

Hadoop Basic Commands

The following example copies the test.txt file from the sshuser home directory on the primary head node to the local system:

Important

scp can only access the file system of individual nodes within the cluster. It cannot be used to access data in the HDFS-compatible storage for the cluster.

Use scp when you need to upload a resource for use from an SSH session. For example, upload a Python script and then run the script from an SSH session.

Command To Generate Ssh Key In Hadoop Download

For information on directly loading data into the HDFS-compatible storage, see the following documents:

• HDInsight using Azure Storage.

• HDInsight using Azure Data Lake Storage.

Hadoop Commands Tutorial

Next steps