How to Use SSH with Linux and Mac on Azure
This topic describes how to use ssh-keygen and openssl on Linux and Mac to create and use ssh-rsa format and .pem format files to secure communication with Azure VMs based on Linux. Creating Linux-based Azure Virtual Machines using the Resource Manager deployment model is recommended for new deployments and takes an ssh-rsa type public key file or string (depending on the deployment client). The Azure portal currently accepts only the ssh-rsa format strings, whether for classic or Resource Manager deployments.
Azure has two different deployment models for creating and working with resources: Resource Manager and classic. This article covers using both models, but Microsoft recommends that most new deployments use the Resource Manager model.
To create these types of files for use on a Windows computer to communicate securely with Linux VMs in Azure, see Use SSH keys on Windows.
A basic ssh setup for Azure includes an ssh-rsa public and private key pair of 2048 bits (by default, ssh-keygen stores these files as ~/.ssh/id_rsa and ~/.ssh/id-rsa.pub unless you change the defaults) as well as a
.pem file generated from the id_rsa private key file for use with the classic deployment model of the classic portal.
Here are the deployment scenarios, and the types of files you use in each:
- ssh-rsa keys are required for any deployment using the Azure portal, regardless of the deployment model.
- .pem file are required to create VMs using the classic portal. .pem files are also supported in classic deployments that use the Azure CLI.
Azure requires ssh-rsa format key files of 2048 bits or the equivalent .pem files, depending upon your scenario. If you already have such files, pass the public key file when creating your Azure VM.
If you need to create the files:
Make sure your implementation of ssh-keygen and openssl is up to date. This varies by platform.
- For Mac, be sure to visit the Apple Product Security web site and choose the proper updates if necessary.
For Debian-based Linux distributions such as Ubuntu, Debian, Mint, and so on:
sudo apt-get update ssh-keygen sudo apt-get update openssl
For RPM-based Linux distributions such as CentOS and Oracle Linux:
sudo yum update ssh-keygen sudo yum update openssl
For SLES and OpenSUSE
sudo zypper update ssh-keygen sudo zypper update openssl
Use ssh-keygen to create a 2048-bit RSA public and private key files, and unless you have a specific location or specific names for the files, accept the default location and name of
~/.ssh/id_rsa. The basic command is:
ssh-keygen -t rsa -b 2048
Typically, your ssh-keygen implementation adds a comment, often the username and host name of the computer. You can specify a specific comment using the
Create a .pem file from your
~/.ssh/id_rsafile to enable you to work with the classic portal. Use the openssl as follows:
openssl req -x509 -key ~/.ssh/id_rsa -nodes -days 365 -newkey rsa:2048 -out myCert.pem
If you want to create a .pem file from a different private key file, modify the
If you plan to manage services deployed with the classic deployment model, you may also want to create a .cer format file to upload to the portal -- although this doesn't involve ssh or connecting to Linux VMS, which is the subject of this article. To create those files on Linux or Mac, type:
openssl.exe x509 -outform der -in myCert.pem -out myCert.cer
To convert your .pem file into a DER encoded X509 certificate file.
You can use ssh-rsa (
.pub) keys for all new work, especially with the Resource Manager deployment model and the preview portal; you may need to create a
.pem file from your keys if you need to use the classic portal.
Once you've created the files you need, there are many ways to create a VM to which you can securely connect using a public-private key exchange. In almost all situations, especially using Resource Manager deployments, pass the .pub file when prompted for an ssh key file path or the contents of a file as a string.
The most common usage is when imperatively creating a VM -- or uploading a template to create a VM. The following code example shows creating a new, secure Linux VM in Azure by passing the public file name (in this case, the default
~/.ssh/id_rsa.pub file) to the
azure vm create command. (The other arguments were previously created.)
azure vm create \ --nic-name testnic \ --public-ip-name testpip \ --vnet-name testvnet \ --vnet-subnet-name testsubnet \ --storage-account-name computeteststore --image-urn canonical:UbuntuServer:14.04.3-LTS:latest \ --username ops \ -ssh-publickey-file ~/.ssh/id_rsa.pub \ testrg testvm westeurope linux
The next example shows the use of the ssh-rsa format with a Resource Manager template and the Azure CLI to create an Ubuntu VM that is secured by a username and the contents of the
~/.ssh/id_rsa.pub as a string. (In this case, the public key string is shortened to be more readable.)
azure group deployment create \ --resource-group test-sshtemplate \ --template-uri https://raw.githubusercontent.com/Azure/azure-quickstart-templates/master/101-vm-sshkey/azuredeploy.json \ --name mysshdeployment info: Executing command group deployment create info: Supply values for the following parameters testnewStorageAccountName: testsshvmtemplate3 adminUserName: ops sshKeyData: ssh-rsa AAAAB3NzaC1yc2EAAAADAQA+/L+rHIjz+nXTzxApgnP+iKDZco9 user@macbookpro dnsNameForPublicIP: testsshvmtemplate location: West Europe vmName: sshvm + Initializing template configurations and parameters + Creating a deployment info: Created template deployment "mysshdeployment" + Waiting for deployment to complete data: DeploymentName : mysshdeployment data: ResourceGroupName : test-sshtemplate data: ProvisioningState : Succeeded data: Timestamp : 2015-10-08T00:12:12.2529678Z data: Mode : Incremental data: TemplateLink : https://raw.githubusercontent.com/Azure/azure-quickstart-templates/master/101-vm-sshkey/azuredeploy.json data: ContentVersion : 188.8.131.52 data: Name Type Value data: newStorageAccountName String testtestsshvmtemplate3 data: adminUserName String ops data: sshKeyData String ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDAkek3P6V3EhmD+xP+iKDZco9 user@macbookpro data: dnsNameForPublicIP String testsshvmtemplate data: location String West Europe data: vmSize String Standard_A2 data: vmName String sshvm data: ubuntuOSVersion String 14.04.2-LTS info: group deployment create command OK
You can then use the .pem file with either the classic portal or with the classic deployment mode and
azure vm create, as in the following example:
azure vm create \ -l "West US" -n testpemasm \ -P -t myCert.pem -e 22 \ testpemasm \ b39f27a8b8c64d52b05eac6a62ebad85__Ubuntu-14_04_3-LTS-amd64-server-20150908-en-us-30GB \ ops info: Executing command vm create warn: --vm-size has not been specified. Defaulting to "Small". + Looking up image b39f27a8b8c64d52b05eac6a62ebad85__Ubuntu-14_04_3-LTS-amd64-server-20150908-en-us-30GB + Looking up cloud service info: cloud service testpemasm not found. + Creating cloud service + Retrieving storage accounts + Configuring certificate + Creating VM info: vm create command OK
The ssh command takes a username to log on with, the network address of the computer, and the port at which to connect to the address -- as well as many other special variations. (For more information about ssh, you might start with this article on Secure Shell)
A typical usage with Resource Manager deployment might look like the following, if you've merely specified a subdomain and a deployment location:
ssh email@example.com -p 22
or, if you are connecting to a classic deployment cloud service the address you would use might look like this:
ssh firstname.lastname@example.org -p 22
Because the address form can change -- you can always use the IP address or perhaps you have a custom domain name assigned -- you'll need to discover the address of your Azure VM.
You can discover the address to use with a VM and the classic deployment model by using the
azure vm show command with the VM name:
azure vm show testpemasm info: Executing command vm show + Getting virtual machines data: DNSName "testpemasm.cloudapp.net" data: Location "West US" data: VMName "testpemasm" data: IPAddress "100.116.160.154" data: InstanceStatus "ReadyRole" data: InstanceSize "Small" data: Image "b39f27a8b8c64d52b05eac6a62ebad85__Ubuntu-14_04_3-LTS-amd64-server-20150908-en-us-30GB" data: OSDisk hostCaching "ReadWrite" data: OSDisk name "testpemasm-testpemasm-0-201510102050230517" data: OSDisk mediaLink "https://portalvhds4blttsxgjj1rf.blob.core.windows.net/vhd-store/testpemasm-2747c9c432b043ff.vhd" data: OSDisk sourceImageName "b39f27a8b8c64d52b05eac6a62ebad85__Ubuntu-14_04_3-LTS-amd64-server-20150908-en-us-30GB" data: OSDisk operatingSystem "Linux" data: OSDisk iOType "Standard" data: ReservedIPName "" data: VirtualIPAddresses 0 address "184.108.40.206" data: VirtualIPAddresses 0 name "testpemasmContractContract" data: VirtualIPAddresses 0 isDnsProgrammed true data: Network Endpoints 0 localPort 22 data: Network Endpoints 0 name "ssh" data: Network Endpoints 0 port 22 data: Network Endpoints 0 protocol "tcp" data: Network Endpoints 0 virtualIPAddress "220.127.116.11" data: Network Endpoints 0 enableDirectServerReturn false info: vm show command OK
azure vm show testrg testvm info: Executing command vm show + Looking up the VM "testvm" + Looking up the NIC "testnic" + Looking up the public ip "testpip"
Examine the network profile section:
data: Network Profile: data: Network Interfaces: data: Network Interface #1: data: Id :/subscriptions/<guid>/resourceGroups/testrg/providers/Microsoft.Network/networkInterfaces/testnic data: Primary :true data: MAC Address :00-0D-3A-21-8E-AE data: Provisioning State :Succeeded data: Name :testnic data: Location :westeurope data: Private IP alloc-method :Static data: Private IP address :192.168.1.101 data: Public IP address :18.104.22.168 data: FQDN :testsubdomain.westeurope.cloudapp.azure.com data: data: Diagnostics Instance View: info: vm show command OK
If you didn't use the default SSH port of 22 when you created the VM, you can discover what ports have inbound rules with the
azure network nsg show command, like the following example:
azure network nsg show testrg testnsg info: Executing command network nsg show + Looking up the network security group "testnsg" data: Id : /subscriptions/<guid>/resourceGroups/testrg/providers/Microsoft.Network/networkSecurityGroups/testnsg data: Name : testnsg data: Type : Microsoft.Network/networkSecurityGroups data: Location : westeurope data: Provisioning state : Succeeded data: Security group rules: data: Name Source IP Source Port Destination IP Destination Port Protocol Direction Access Priority data: ----------------------------- ----------------- ----------- -------------- ---------------- -------- --------- ------ -------- data: testnsgrule * * * 22 Tcp Inbound Allow 1000 data: AllowVnetInBound VirtualNetwork * VirtualNetwork * * Inbound Allow 65000 data: AllowAzureLoadBalancerInBound AzureLoadBalancer * * * * Inbound Allow 65001 data: DenyAllInBound * * * * * Inbound Deny 65500 data: AllowVnetOutBound VirtualNetwork * VirtualNetwork * * Outbound Allow 65000 data: AllowInternetOutBound * * Internet * * Outbound Allow 65001 data: DenyAllOutBound * * * * * Outbound Deny 65500 info: network nsg show command OK
If you created a VM using a .pem file created from your
~/.ssh/id_rsa file, you can directly ssh into that VM. Note that when you do, the certificate handshake will use your private key at
~/.ssh/id_rsa. (The VM creation process computes the public key from the .pem and places the ssh-rsa form of the public key in
~/.ssh/authorized_users.) Connecting might look like the following example:
ssh email@example.com -p 22 The authenticity of host 'testpemasm.cloudapp.net (22.214.171.124)' can't be established. RSA key fingerprint is dc:bb:e4:cc:59:db:b9:49:dc:71:a3:c8:37:36:fd:62. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added 'testpemasm.cloudapp.net,126.96.36.199' (RSA) to the list of known hosts. Welcome to Ubuntu 14.04.3 LTS (GNU/Linux 3.19.0-28-generic x86_64) * Documentation: https://help.ubuntu.com/ System information as of Sat Oct 10 20:53:08 UTC 2015 System load: 0.52 Memory usage: 5% Processes: 80 Usage of /: 45.3% of 1.94GB Swap usage: 0% Users logged in: 0 Graph this data and manage this system at: https://landscape.canonical.com/ Get cloud support with Ubuntu Advantage Cloud Guest: http://www.ubuntu.com/business/services/cloud 0 packages can be updated. 0 updates are security updates. The programs included with the Ubuntu system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law.
You can read the suggestions at Troubleshooting SSH Connections to see if they can help resolve the situation.
Now that you've connected to your VM, make sure to update your chosen distribution before continuing to use it.