I might have done something extremely stupid. I don't really know what I'm doing with this but have been following online guides to set up an EC2 Instance running Bitnami Wordpress.
Today I attempted to follow this guide to link Vaultpress to my instance:
https://www.virtualizationhowto.com/2016/04/connect-vaultpress-aws-ec2-instance/
I think I may have misstepped and pasted the public key text in the .ssh/authorized_keys inside the root user, overwriting whatever was there, (if there is information there by default?). I think, however, I was under a new user I created earlier, named vaultpress.
It is also possible that when I tried to add security groups I overwrote something something important. I have now reset the default VPC group and Security group generated by AWS Marketplace to 0.0.0.0/0 for SSH, so if I understand correctly that should be OK now?
Either way, I can now no longer SSH in with my .pem file. I did CHMOD 600 to the .pem file and used the standard ssh -i "thefile.pem" bitnami#address.com. Not sure where to go from here. Are there other ways to access the instance?
I get permission denied (public key)
ANY HELP REALLY APPRECIATED!
I thought I was going to make big track on my project with my day off today. Guess it's one step forward and two back today.
Related
From what I read, ~/.ssh/authorized_keys just take what is in the project level metadata. If i delete an entry from the console, it disappears from the authorized_keys file too.
However, if i delete from the authorized_keys file, the console still shows the entry with the deleted public key.
Once I exit the ssh session, I'm then not able to go back in with either gcloud compute ssh user#instance_name or ssh user#instance_ip. Why is this so?
I had to then go to the console and delete that entry (that i previously removed by editting authorized_keys file directly) and only now gcloud compute ssh user#instance_name works properly again, helping me add my google_compute_engine.pub into project metadata so ssh user#instance_ip now works too.
P.S I'm unfamiliar with how instance level metadata works so only experimented with project level metadata ssh keys. If any answer can comment whether your answer applies to instance level too that'll be great.
One can provide SSH keys either on the project or instance level. Please don't edit files, but add them on the GCE console, becaause they're generally managed by GCP. So that one can even eg. generate and provision a new key, run a script, let the key expire. Alike this one does not have to store the key anywhere ...which is quite unlike a traditional VM. The amount of keys one can add into instance meta-data is limited.
Currently, I am facing an issue related to AWS. A project is already uploaded on AWS server and always connect to that Project by using PEM key of that particular project. But from last week I am not able to connect with the AWS server by using the PEM key. I got one solution for this, as by creating new instance i will be able to got my access on the project but this will make me lose of my whole data & database as a result. Is this occurred due to virus or any thing else? Got stuck over here badly. Any help will be appreciable.
I think the authorized_keys file has some incorrect entries. Let's remove the key from the file and add it again.
remove the host key
ssh-keygen -R [hostname]
ssh again
ssh -Tv ec2-user#example.com -i ~/mykey.pem
In order to use existing EBS volume with data in a new ec2, with a new ssh key:
Create a snapshot of the current instance's EBS, and create a volume.
Create a new instance with a new ssh key.
Stop the new instance and attached the previously created volume as the boot volume.
Start the new instance and you should be able to login with the new ssh key.
The log indicates that you do not have any networking issues. It is the ssh server on the instance that is rejecting your connection.
The first thing to confirm is that you are connecting to the correct Amazon EC2 instance. If an EC2 instance is stopped and started again, it might change public IP address (depending how it is configured). Therefore, make sure that you are connecting to the right instance.
Next, confirm that you are using the correct username. You are using ubuntu#, which is correct if the instance is using an Ubuntu AMI. However, it is possible to create additional users on a Linux computer and the PEM files are associated with specific users. Therefore, confirm that this is the correct username for use with that PEM file.
Next, confirm that you are using the correct PEM file. The PEM file should contain the private half of a keypair that matches the public half that is stored on the instance in the user's ~.ssh/authorized_keys file. The log indicates that the instance is rejecting the provided keypair. Therefore, you might be using the wrong one.
Failing all this, there are some recommended steps available on: Walkthrough: Reset Passwords and SSH Keys on Amazon EC2 Instances - AWS Systems Manager
However, they might not work since you are using an Ubuntu instance, which might not have standard AWS software installed.
Let us know how you go!
A little backstory, I have an AWS instance made with Bitnami that I set up on my Windows Machine back home. I am currently out of the country and have no way to access that machine at the moment. One month later, I visit the website getting a 500 error and (only my Macbook on me). I've tried to SSH into it from my Macbook and no luck. I get the error:
Username is not in the sudoers file. This incident will be reported.
I've also tried another way to SSH into my aws but then I just get
Permission denied (publickey).
I do have the public/private keys I made with me so I am not sure if I had to set up some additional permissions to SSH from a different computer. On top of that, I got an email stating that someone attempted to access remote hosts on the internet without authorization. If I visit my Public IP address of my instance, it goes straight to a spam page.
At this point, I am not sure if I am just missing something in my steps or have missed a step. If someone can help me, I would really appreciate it.
Is there some way to get my instance back up and running? If not, is there some way I can back up the wordpress files on that instance that's down and use it to create another one on my Macbook currently? Please let me know.
If you have the private key that your AWS instance has been installed with, place the key in ~/.ssh .
Then, run the following command to set the permissions of the key to read and write only to your user (it's a mandatory step):
chmod 600 ~/.ssh/keyname
Then, run the following command to connect to your instance:
ssh -i ~/.ssh/keyname user#instance_ip
And it should connect successfully.
If you're not sure which user to connect to and you have access to AWS EC2 Console, then look for that server, right-click it and choose "Connect" and it will usually show the correct user to use when connecting to it by SSH.
Here's my issue
I have an ec-2 instance on AWS running Ubuntu Server. During the initial launch of the instance, I generated the key-pair by going to AWS console --> Key Pairs --> Create key pair. It generated a key abcxxxx.pem and I have saved it.
Here's where the issue starts
I head a project where multiple developers come on and off. Without
too much thought, I distributed my .pem file to 2-3 developers. They
have left the project since and I want to restrict AWS access to only active
developers. Basically I don't want the 2-3 developers (with .pem file) to access my machine.
For all the new developers ( I no longer distribute .pem file), I give access to AWS machine by pasting
there public key in /home/ubuntu/.ssh/authorized_keys. This
gives them access to the machine.
My two questions are as follows
How can I restrict access to people who already have .pem file?
Will deleting their public key from /home/ubuntu/.ssh/authorized_keys make a difference? NOTE: I still have the key and only I have the access to AWS console.
How are the new developers able to access the AWS machine without a .pem file? (The only thing I do is paste their public key in the authorized_keys on AWS)
How do I implement a system where I have sole access and I deal with developers coming on/off on the project?
All users(including me) who's public key is in the authorized_keys on AWS machine can login without a .pem file. How is this possible? Doesn't everyone need a .pem file to ssh in?
I'm really confused about this key-pair business (what's the role of .pem file?) and other posts online don't seem to help (even AWS support). Most posts online address scenarios where you lose the key and you have launch a new instance etc. etc. I contacted AWS support and they just sent me this link. I don't understand how this helps.
Any solution/elaborate answer will be really helpful.
For the most part, your question is really about how to administrate users and SSH on Ubuntu. The keypair that you generated using the console is only used when the instance first launches. It is always available via instance metadata; you can see that by running the following command from the shell on the EC2 instance:
$ curl http://169.254.169.254/latest/meta-data/public-keys/0/openssh-key
which outputs:
ssh-rsa ...blah blah blah...
When your EC2 instance first launched, this key was copied into /home/ubuntu/.ssh/authorized_keys because the Ubuntu AMI you're using is set up to do that. But that's just a convention. That's the only time that the key will get automatically copied anywhere, so from there on out you can manage the authorized_keys file however you like.
Regarding your specific questions,
If the original public key you created on the console is still in authorized_keys, then anyone who has the corresponding PEM file can still log in. To correct this, you would need to carefully remove that key from the authorized_keys file (for example, first making absolutely sure that you can log in with a different key).
While they may not have the PEM file you downloaded from the AWS Console, they must somehow have gotten the PEM file (or some rough equivalent) for one of the public keys that you added to authorized_keys.
There are lots of different ways. As mentioned above, it's more of a matter of how you want to administrate users under Ubuntu. Since you seem to want to retain control over the machine, you could create user accounts for each of the developers to log into, and then give them limited rights to use sudo in certain cases (assuming they need that at all). You could then revoke these accounts whenever you wanted.
My understanding is that there are just many different ways to provide the equivalent of a PEM file to ssh, and somehow you (and your developers) must be doing that. I'd recommend perusing the ssh documentation.
I hope this helps!
Taking a stab at this:
1) You cannot remove the key from authorized_keys without losing access yourself to the server. The public key in there proves to the server that you are who you say you are when you auth to the server via SSH using the pem.
2) For the new developers, they do pass in a key when the ssh to the machine. It's just their key and it's implicitely passed in, vs the key you've used to spin up the machine. The presence of their public key in the authorized_keys signals to the server that they are authorized to access the machine once their ssh client proves it has the private key that matches the public key in the authorized file.
3) i would just create additional users on the box and set them up for passwordless login by setting up /home/newusername/.ssh/authorized_keys pretty much the same way you set it up for the ubuntu user today. when they leave the project just disable and/or delete the accounts
4) It's possible to login without specifing a pem, but you still specify a key. To see the key exchange and how the auth takes place do "ssh -vvv user#machinename" and you will see the whole ssh dialogue. When you don't specify a key, the ssh client will look for one in a couple of predefined locations. you will see the client attempt to use each of these keys (you're probably picking something up from ~/.ssh/id_*). A pem is not a magic file. It just keys (it may contain a public key, a public and a private key or a public key and the whole cert chain).
I would recommend you read on public/private key crypto to understand how it works.
https://en.wikipedia.org/wiki/Public-key_cryptography
https://www.youtube.com/watch?v=svRWcx7dT8g
https://staff.washington.edu/dittrich/misc/ssh/
I was trying to access Amazon EC2 instance without using keypairs (I was doing some tests with Dreamweaver)
So, I had a marvelous ideia of changing sshd_config file.
sudo nano /etc/ssh/sshd_config
And I change the PasswordAuthentication line to:
Match User ubuntu
PasswordAuthentication yes
After restarting I got a sad surprise. I cannot access my machine anymore. And even worst I had only one user (ubuntu) on this instance.
My question is:
How can I back to original setting ( roolback sshd_config file) if I cannot access my terminal?
Loosing access to an Amazon EC2 instance is a common encounter - how to approach this situation when you don't know the reason yet is addressed in Eric Hammond's excellent summary Solving: "I can't connect to my server on Amazon EC2".
However, since you already now that the problem is permission related, you can apply his respective instructions Fixing Files on the Root EBS Volume of an EC2 Instance right away, see my answer to the related question Fixing Amazon EC2 Permissions for a short summary of this approach.
Good luck!