SSH to Cloud VM
Shell, or SSH, is used to administering and managing Linux workloads. Before trying to access instances from the outside world, you need to make sure you have followed these steps:
- You followed the instruction in Create a Key Pair to set up a public ssh key.
- Your public ssh-key was selected (in the Access and Security tab) while launching the instance.
- Assign a Floating IP to the instance in order to access it from outside world.
- Make sure you have added rules in the Security Groups to allow ssh to the instance.
Make a note of the floating IP you have associated to your instance.
In our example, the IP is
Default usernames for all the base images are:
- all Ubuntu images: ubuntu
- all CentOS images: centos
- all Rocky Linux images: centos
- all Fedora images: fedora
- all Debian images: debian
- all RHEL images: cloud-user
Our example VM was launched with the ubuntu-22.04-x86_64 base image, the user we need is 'ubuntu'.
Open a Terminal window and type:
Since you have never connected to this VM before, you will be asked if you are
sure you want to connect. Type
If you haven't added your key to ssh-agent, you may need to specify the
private key file, like this:
ssh -i ~/.ssh/cloud.key firstname.lastname@example.org
Setting a password
When the VMs are launched, a strong, randomly-generated password is created for the default user, and then discarded.
Once you connect to your VM, you will want to set a password in case you ever need to log in via the console in the web dashboard.
For example, if your network connections aren't working right.
Since you are not using it to log in over SSH or to sudo, it doesn't really matter how hard it is to type, and we recommend using a randomly-generated password.
Create a random password like this:
ubuntu@test-vm:~$ cat /dev/urandom | base64 | dd count=14 bs=1 T1W16HCyfZf8V514+0 records in 14+0 records out 14 bytes copied, 0.00110367 s, 12.7 kB/s
The 'count' parameter controls the number of characters.
The first [count] characters of the output are your randomly generated output,
followed immediately by "[count]+0",
so in the above example the password is:
Set the password for ubuntu using the command:
ubuntu@test-vm:~$ sudo passwd ubuntu New password: Retype new password: ... password updated successfully
Store the password in a secure place. Don't send it over email, post it on your wall on a sticky note, etc.
Adding other people's SSH keys to the instance
You were able to log into using your own SSH key.
Right now Openstack only permits one key to be added at launch, so you need to add your teammates keys manually.
Get your teammates' public keys. If they used ssh-keygen to create their key,
this will be in a file called
If they created a key via the dashboard, or imported the key created with ssh-keygen, their public key is viewable from the Key Pairs tab.
Click on the key pair name. The public key starts with 'ssh-rsa' and looks something like this:
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDL6O5qNZHfgFwf4vnnib2XBub7ZU6khy6z6JQl3XRJg6I6gZ +Ss6tNjz0Xgax5My0bizORcka/TJ33S36XZfzUKGsZqyEl/ax1Xnl3MfE/rgq415wKljg4 +QvDznF0OFqXjDIgL938N8G4mq/ cKKtRSMdksAvNsAreO0W7GZi24G1giap4yuG4XghAXcYxDnOSzpyP2HgqgjsPdQue919IYvgH8shr +sPa48uC5sGU5PkTb0Pk/ef1Y5pLBQZYchyMakQvxjj7hHZaT/ Lw0wIvGpPQay84plkjR2IDNb51tiEy5x163YDtrrP7RM2LJwXm+1vI8MzYmFRrXiqUyznd test_user@demo
Create a file called something like 'teammates.txt' and paste in your team's public keys, one per line.
Hang onto this file to save yourself from having to do all the copy/pasting every time you launch a new VM.
Copy the file to the vm:
[you@your-laptop ~]$ scp teammates.txt email@example.com:~
If the copy works, you will see the output:
teammates.txt 100% 0 0KB/s 00:00
Append the file's contents to authorized_keys:
[cloud-user@test-vm ~] #cat teammates.txt >> ~/.ssh/authorized_keys
Now your teammates should also be able to log in.
Make sure to use
>> instead of
> to avoid overwriting your own key.
Adding users to the instance
You may decide that each teammate should have their own user on the VM instead of everyone logging in to the default user.
Once you log into the VM, you can create another user like this.
The 'sudo_group' is different for different OS - in CentOS and Red Hat, the group is called 'wheel', while in Ubuntu, the group is called 'sudo'.
$ sudo su # useradd -m <username> # passwd <username> # usermod -aG <sudo_group> <username> <-- skip this step for users who # should not have root access # su username $ cd ~ $ mkdir .ssh $ chmod 700 .ssh $ cd .ssh $ vi authorized_keys <-- paste the public key for that user in this file $ chmod 600 authorized_keys