After changing two passwords, root and the default user, suddenly we notice now that the "in browser" link on Google Compute Engine fails to connect via SSH.
Strangely, however, if we use the SSH command from the command line that Google provides (i.e. $ gcloud compute ssh VM-NAME --zone VM-ZONE) - SSH works.
It appears SSH is working - but the "in browser" SSH link no longer connects. What might have gone wrong and how do we fix this?
ADDENDUM:
Of note, a commenter below suggests it is not related to passwords but purely SSH keys - so it looks the answer to this question might rest around if there is a way to regenerate SSH keys on GCE instances. We are searching. If anyone knows code to regenerate SSH keys for GCE please post.
GCE VMs, by default, don't allow for SSH connections with clear-text password: it uses keys instead. You can specify approved keys during VM instantiation, or at a later time, but one that is always present is the key to the user account you used when creating the machine.
As long as you haven't modified /etc/ssh/sshd_config, this should continue to be the case. Either way, one more option you can use to connect via SSH to your instance is to run the following command:
$ gcloud compute ssh VM-NAME --zone VM-ZONE
while logged in with your authorized user account.
ADDENDUM - In lieu of regenerating previous keys, you can add additional, locally-generated SSH keys on both the project, as well as on the VM level. The first applies to all VMs and grants access to project owners and editors, while the second only applies to the VM in question. Both methods add the SSH entered to the Metadata server, from which the get uploaded to the VM prior to SSH connection to all / the VM.
You can do this from the Developers Console:
project-level SSH keys - go to your project -> Compute -> Compute Engine -> Metadata -> "SSH KEYS" (top of the screen) -> click on "Edit"
VM-level SSH keys - go to your project -> Compute -> Compute Engine -> VM instances -> click on the instance name -> "SSH keys" section (scroll down) -> click "Add SSH key"
We discovered the cause was a chown command we had executed on a directory for the primary user that Google creates on the Google Compute Engine instance.
By reversing that chown back to the Google created user, Google's in-browser SSH began working again.
We used chown on an entire user directory and also an ssh config file back to the Google created user using:
chown -R user_name_com /home/user_name_com
and also on this file
chown user_name_com /etc/ssh/ssh_config
where user_name_com was our gmail email address user.
Related
I have installed ansible in on of my GCE Debian VM Instance(1). Now I want to connect to another GCE Debian VM instance(2).
I have generated the public key on Instance 1 and copied the .pub key manually to the the authorized key of instance 2.
But, when I try to do the ssh from 1 to 2 it gives permission denied.
Is there any other way round? I am a little new to this, trying to learn.
is there any step by step guide available? and also what is the exact ip address to do ssh on? will it be the internal IP or the External IP taken by GCE when the Instance is started.
I'm an Ansible user too and I manage a set of compute engine servers. My scenario is pretty close to yours so hopefully this will work for you as well. To get this to work smoothly, you just need to realise that ssh public keys are metadata and can be used to tell GCE to create user accounts on instance creation.
SSH public keys are project-wide metadata
To get what you want the ssh public key should be added to the Metadata section under Compute Engine. My keys look like this:
ssh-rsa AAAAB3<long key sequence shortened>Uxh bob
Every time I get GCE to create an instance, it creates /home/bob and puts the key into the .ssh/authorized_keys section with all of the correct permissions set. This means I can ssh into that server if I have the private key. In my scenario I keep the Private Key only in two places, LastPass and my .ssh directory on my work computer. While I don't recommend it, you could also copy that private key to the .ssh directory on each server that you want to ssh from but I really recommend getting to grips with ssh-agent
Getting it to work with Ansible
The core of this is to tell Ansible not to validate host checking and to connect as the user specified in the key (bob in this example). To do that you need to set some ssh options when calling ansible
ansible-playbook -ssh-common-args='-o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no' -u bob
Now Ansible will connect to the servers mentioned in your playbook and try to use the local private key to negotiate the ssh connection which should work as GCE will have set things up for you when the VM is created. Also, since hostname checking is off, you can rebuild the VM as often as you like.
Saying it again
I really recommend that you run ansible from a small number of secure computers and not put your private key onto cloud servers. If you really need to ssh between servers, look into how ssh-agent passes identity around. A good place to start is this article.
Where did you say the metadata was?
I kind of glossed over that bit but here's an image to get you started.
From there you just follow the options for adding a public key. Don't forget that this works because the third part of the key is the username that you want GCE and Ansible to use when running plays.
It's quite simple if you have two instances in google cloud platform, automatically you have the guest environment installed (gcloud command line), with it you can ssh through all you ssh inside your project:
Just run the following command line for inside your instance A to reach the Instance B
[user#Instance(1)]$ gcloud compute ssh Instance(2) --zone [zone]
That it, if it's not working let me know, and verify if your firewall rule let internal traffic.
We have a user that is allowed to SSH into an VM on the Google Cloud Platform.
His key is added to the VM and he can SSH using
gcloud compute ssh name-of-vm
However connecting in this way will always have gcloud try to update project wide meta data
Updating project ssh metadata...failed
It fails because he only has rights for accessing & administrating this VM
However it's very annoying that every time he has to connect in this way he has to to wait for GCP trying to update metadata, which is not allowed and then check the sshkeys on the machine.
Is there a flag in the command to skip checking/updating project wide ssh keys?
Yes we can 'block project wide ssh keys' on the instance, but that would mean that other project admins cannot log in anymore.
I've also tried to minimise access to this user.
But, ideally, what rights should he have if he is allowed to SSH to the machine, start & stop the instance and store data into a bucket?
What you can do is to enable-oslogin for all the users you need including admins, enabling OS Login on instances disables metadata-based SSH key configurations on those instances.
The role to start, stop and connect via SSH to an instance would be roles/compute.instanceAdmin (take in account that this role is currently in beta) you can check here a list of the Compute Engine roles available so you can choose the one that better suits your needs.
To store data into a bucket, I think the most suitable role is roles/storage.objectCreator that allows users to create objects but not to delete or overwrite objects.
I found this solution very useful.
Create a file called config under ~/.ssh
Add the following to it. Change nickname to anything you prefer, $IP_OF_INSTANCE to the public IP of the instance, and $USER to your machine username.
Host nickname
HostName $IP_OF_INSTANCE
Port 22
User $USER
CheckHostIP no
StrictHostKeyChecking no
IdentityFile ~/.ssh/google_compute_engine
Now, you can simply SSH using:
ssh nickname
Note that the path on Linux and Mac is ~/.ssh while the path on Windows is something like C:\Users\<user>\.ssh
Re: #1: There's no flag on the command to change this behavior on a per-command level instead of a per-instance level ('block-project-ssh-keys', as you mentioned) but you could file a FR at https://issuetracker.google.com/savedsearches/559662.
I am not able to access the google compute engine instance using ssh or gcutil ssh. I have tried adding my local machine keys into metadata and shh keys of the specific instance. How to achieve access using a shh-client?
this is the link to the guides i followed.
Google Compute Engine - troubleshooting SSH "Connection refused"
https://cloud.google.com/compute/docs/instances/connecting-to-instance#standardssh
the official way is google compute ssh [instance-name]
If this isn't what you did to get the error, let me know and I'll try.
Just to let you know Google Compute Engine recommends that all users transition to the gcloud compute tool from gcutil. gcloud compute is a unified command-line tool that features a number of improvements over gcutil link.
To connect to Google compute Engine you need tor run the below command in your cloud Shell:
gcloud compute ssh [INSTANCE_NAME]
Here a the public documentation, If you want to ssh from inside an instance just run the same command line above.
The trick here is to use the -C (comment) parameter to specify your GCE userid.
If the Google user who owns the GCE instance is myname#gmail.com (which you will use as your login userid), then generate the key pair with (for example)
ssh-keygen -b521 -t ecdsa -C myname -f mykeypair
When you paste mykeypair.pub into the instance's public key list, you should see "myname" appear as the userid of the key.
Setting this up will let you use ssh, scp, etc from your command line.
Two days ago I've created a compute engine instance and connected to it with ssh, everything was fine, after testing different things i've deleted the machine and disk.
Today I've created a new instance in compute engine, getinstance as well as the console show the instance running.
But when trying to connect to the instance I'm getting a messegebox asking for: enter your password for the ssh key "google compute engine"
the password i'm entering is getting denied
how can I change the password for this project? this user?
This is how I resolved the issue:
turn hidden files on on finder (by running: defaults write
com.apple.Finder AppleShowAllFiles TRUE)
going to $HOME/.ssh directory and delete the files google_compute_engine, google_compute_engine.pub
call gcutil ssh again which created new files with new passphrase
when prompted again enter the passphrase and connection established :)
Jenkins keeps using the default "jenkins" user when executing builds. My build requires a number of SSH calls. However these SSH calls fails with Host verification exceptions because i haven't been able connect place the public key for this user on the target server.
I don't know where the default "jenkins" user is configured and therefore cant generate the required public key to place on the target server.
Any suggestions for either;
A way to force Jenkins to use a user i define
A way to enable SSH for the default Jenkins user
Fetch the password for the default 'jenkins' user
Ideally I would like to be able do both both any help greatly appreciated.
Solution: I was able access the default Jenkins user with an SSH request from the target server. Once i was logged in as the jenkins user i was able generate the public/private RSA keys which then allowed for password free access between servers
Because when having numerous slave machine it could be hard to anticipate on which of them build will be executed, rather then explicitly calling ssh I highly suggest using existing Jenkins plug-ins for SSH executing a remote commands:
Publish Over SSH - execute SSH commands or transfer files over SCP/SFTP.
SSH - execute SSH commands.
The default 'jenkins' user is the system user running your jenkins instance (master or slave). Depending on your installation this user can have been generated either by the install scripts (deb/rpm/pkg etc), or manually by your administrator. It may or may not be called 'jenkins'.
To find out under what user your jenkins instance is running, open the http://$JENKINS_SERVER/systemInfo, available from your Manage Jenkins menu.
There you will find your user.home and user.name. E.g. in my case on a Mac OS X master:
user.home /Users/Shared/Jenkins/Home/
user.name jenkins
Once you have that information you will need to log onto that jenkins server as the user running jenkins and ssh into those remote servers to accept the ssh fingerprints.
An alternative (that I've never tried) would be to use a custom jenkins job to accept those fingerprints by for example running the following command in a SSH build task:
ssh -o "StrictHostKeyChecking no" your_remote_server
This last tip is of course completely unacceptable from a pure security point of view :)
So one might make a "job" which writes the host keys as a constant, like:
echo "....." > ~/.ssh/known_hosts
just fill the dots from ssh-keyscan -t rsa {ip}, after you verify it.
That's correct, pipeline jobs will normally use the user jenkins, which means that SSH access needs to be given for this account for it work in the pipeline jobs. People have all sorts of complex build environments so it seems like a fair requirement.
As stated in one of the answers, each individual configuration could be different, so check under "System Information" or similar, in "Manage Jenkins" on the web UI. There should be a user.home and a user.name for the home directory and the username respectively. On my CentOS installation these are "/var/lib/jenkins/" and "jenkins".
The first thing to do is to get a shell access as user jenkins in our case. Because this is an auto-generated service account, the shell is not enabled by default. Assuming you can log in as root or preferably some other user (in which case you'll need to prepend sudo) switch to jenkins as follows:
su -s /bin/bash jenkins
Now you can verify that it's really jenkins and that you entered the right home directory:
whoami
echo $HOME
If these don't match what you see in the configuration, do not proceed.
All is good so far, let's check what keys we already have:
ls -lah ~/.ssh
There may only be keys created with the hostname. See if you can use them:
ssh-copy-id user#host_ip_address
If there's an error, you may need to generate new keys:
ssh-keygen
Accept the default values, and no passphrase, if it prompts you to add the new keys to the home directory, without overwriting existing ones. Now you can run ssh-copy-id again.
It's a good idea to test it with something like
ssh user#host_ip_address ls
If it works, so should ssh, scp, rsync etc. in the Jenkins jobs. Otherwise, check the console output to see the error messages and try those exact commands on the shell as done above.