RELATED APPLICATIONS. This application is a continuation of U.S. Patent application Ser. 11/926,853, filed on Oct. 29, 2007, entitled a RE-KEYING BASED ON PRE-GENERATED KEYS, by Vaibhave Agarwal et al., which is hereby incorporated by reference.
- May Have Pre-generate Ssh Host Keys 2016
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![Host Host](/uploads/1/2/6/0/126048720/348609340.jpg)
May Have Pre-generate Ssh Host Keys 2016
- Before adding a new SSH key to the ssh-agent to manage your keys, you should have checked for existing SSH keys and generated a new SSH key. When adding your SSH key to the agent, use the default macOS ssh-add command, and not an application installed by macports.
- The.pub file is your public key, and the other file is the corresponding private key. If you don’t have these files (or you don’t even have a.ssh directory), you can create them by running a program called ssh-keygen, which is provided with the SSH package on Linux/macOS systems.
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The focus of this article is to explain how Azure Batch compute nodes existwith an Azure deployment, interactive SSH, and the concept of SSH tunnelingto a Docker Host on an Azure Batch compute node from your local machine.
Azure Batch Deployments and Port Exposure
Azure Batch compute nodes which comprise a pool are behind a NAT/load balancerwhich have certain endpoints exposed on the public IP of the deployment tospecific instances (i.e., compute nodes).
For instance, port 12345 may map to port 22 of the first instance of acompute node in the pool for the public IP address 1.2.3.4. The next computenode in the pool may have port 22 mapped to port 12346 on the load balancer.
This allows many compute nodes to sit behind one public IP address.
SSH Keypair Generation
In order to use SSH, you will need to generate a public/private RSA keypairthat SSH requires for asymmetric key authentication. If you are runningBatch Shipyard on Linux/Mac (orWindows with
ssh-keygen
accessible in your %PATH%
or current working directory), youcan opt to leave ssh_public_key
and ssh_private_key
unspecified or emptyin ssh
configuration blocks and Batch Shipyard will automatically generatethe keypair for you. Alternatively, you can specify the location ofpre-generated keypairs that you may have on your system.On Windows, if you don't have
ssh-keygen
available as per above, you canuse PuTTYgento pre-generate public/private keys and then specify the file path inssh_public_key
and ssh_private_key
in ssh
configuration blocks. Tocreate compatible keys for use with Batch Shipyard, perform the followingactions:- Launch PuTTYgen
- Click on the
Generate
button on the bottom right - Move the mouse around as directed to generate randomness for the keys
- Save the RSA private key portion as a file
- Click on
Conversions
file menu at the top - Click
Export OpenSSH key
- A prompt will ask if it is ok to save the key without a passphrase.Click
Yes
. - Save the file to a path accessible by Batch Shipyard
- Click on
- Save the RSA public key portion either as text data or as a file. This isdone by selecting all of the text under the box labeled
Public key for pasting into OpenSSH authorized_keys file:
and pressingCTRL+C or right-click and Copy.- If using the raw data, populate your
ssh
config property namedssh_public_key_data
with the key data from the box - If you are saving the key data to a file, then populate your
ssh
config property namedssh_public_key
and point it to the file
- If using the raw data, populate your
Interactive SSH
By adding an SSH user to the pool (which can be automatically done for youvia the
ssh
block in the pool config upon pool creation or through thepool user add
command), you can interactively log in to compute nodes in thepool and execute any command on the remote machine, including Dockercommands via sudo
.You can utilize the
pool ssh
command to automatically connect to anycompute node in the pool without having to manually resort to pool nodes grls
and issuing the ssh
command with the appropriate parameters. If you havethe SSH private key in the default location or as specified in thegenerated_file_export_path
, then an interactive SSH session will becreated to the compute node specified.pool ssh
can accept either option --cardinal
or the option --nodeid
.If using --cardinal
it requires the natural counting number from zeroassociated with the list of nodes as enumerated by pool nodes grls
. If using--nodeid
, then the exact compute node id within the pool specified inthe pool config must be used. If neither option is specified, the defaultis --cardinal 0
. For example:would create an interactive SSH session with the first compute node in thepool as listed by
pool nodes grls
.Securely Connecting to the Docker Socket Remotely via SSH Tunneling
To take advantage of this feature, you must install Docker locally on yourmachine and have
ssh
available. You can find guides to install Dockeron various operating systems here.The typical recommendation is to secure the Docker daemon if beingaccessed remotely via certificates and TLS. Because SSH is already configuredon all of the nodes with authorized users to use the Docker daemon withBatch Shipyard, we can simply use SSH tunneling instead which simplifiesthe process and is less likely to be blocked in outbound firewall rules.This method is secure as the tunnel is opened and encrypted via
ssh
witha public/private RSA key pair. Please note that the Docker daemon portis not mapped on the NAT/load balancer, so it is impossible to connect tothe port remotely without an SSH tunnel.By specifying
generate_docker_tunnel_script
as true
in the ssh
configuration block in the pool config, a file namedssh_docker_tunnel_shipyard.sh
will be generated on pool add
if anSSH user is specified, on pool user add
when a pool user is added, onpool resize
when a pool is resized, or on pool nodes grls
when a pool'sremote login settings are listed.May Have Pre-generate Ssh Host Keys List
This script simplifies creating an SSH tunnel to the Docker socket fromyour local machine. It accepts a cardinal number of the node to connectto, similar to the
--cardinal
option for pool ssh
. So if you wereconnecting to the first node in the pool, you would execute the dockertunnel script as:This will background the SSH tunnel to the remote Docker daemon and outputsomething similar to the following:
Now you can run the
docker
command locally but have these actionswork remotely through the tunnel on the compute node with the appropriate-H
option as noted above. For instance:would place the current shell context inside the busybox container runningremotely on the Batch compute node.
Alternatively you can export an environment variable named
DOCKER_HOST
which will work for all docker
invocations until the environment variableis unset. For example:would create a busybox container on the remote compute node similar tothe prior command.
To run a CUDA/GPU enabled docker image remotely with nvidia-docker, first youmust installnvidia-docker locallyin addition to docker as per the initial requirement. You can installnvidia-docker locally even without an Nvidia GPU or CUDA installed. It issimply required for the local command execution. If you do not have an NvidiaGPU available and install
nvidia-docker
you will most likely encounter anerror with the nvidia docker service failing to start, but this is ok. Youcan then launch your CUDA-enabled Docker image on the remote compute nodeon Azure N-series VMs the same as any other Docker image except invokingwith the nvidia-docker
command instead:Once you are finished with running your
docker
and/or nvidia-docker
commands remotely, you can terminate the SSH tunnel by sending a SIGTERM tothe SSH tunnel process. In this example, the pid is 22204 as displayed bythe script, thus we would terminate the SSH tunnel with the following:Finally, please remember that the
ssh_docker_tunnel_shipyard.sh
scriptis generated and is specific for the pool as specified in the poolconfiguration file at the time of pool creation, resize, when an SSH useris added or when the remote login settings are listed.How do I create a host key file to use with my applications as I can not use system defined /etc/ssh/ssh_host_rsa_key for non-root account under Linux / Unix / Apple OS X / *BSD operating systems?
You need to use a command called ssh-keygen. This command generates, manages and converts authentication keys for ssh. It can create RSA keys for use by SSH protocol version 1 and RSA or DSA keys for use by SSH protocol version 2. he type of key to be generated is specified with the -t option. If invoked without any arguments, ssh-keygen will generate an RSA key for use in SSH protocol 2 connections. The -f option specifies the filename of the key file.
You need to use a command called ssh-keygen. This command generates, manages and converts authentication keys for ssh. It can create RSA keys for use by SSH protocol version 1 and RSA or DSA keys for use by SSH protocol version 2. he type of key to be generated is specified with the -t option. If invoked without any arguments, ssh-keygen will generate an RSA key for use in SSH protocol 2 connections. The -f option specifies the filename of the key file.
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Why create a new host key files?
You may need a new key file:
- Your system is compromised.
- Your keys are stolen.
- You forgotten the passphrase.
- Your application need a new host key.
- You can not read the default system key files stored in /etc/ssh/ directory but your non-root application needs key.
- You got an error message which read as “Could not load host key: /etc/ssh/ssh_host_key*”.
ssh-keygen Syntax
The syntax is:
Example
Create a host key file in your $HOME/.ssh/myapp as follows. First, create a directory to store your host key file, enter:
To create a host RSAv2 key file, run:
Sample outputs:
$ mkdir -p $HOME/.ssh/myapp
To create a host RSAv2 key file, run:
$ ssh-keygen -t rsa -f $HOME/.ssh/myapp/rsa_key_file
Sample outputs:
Type the following commands to verify the keys:
Sample outputs:
$ ls -l $HOME/.ssh/myapp/
Sample outputs:
You can now use keys with your app:
$ mycool-app -key $HOME/.ssh/myapp/rsa_key_file -d
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