I have used servers on amazon AWS where they send me a public key .pem file and when I ssh in, all I have to do is:
ssh -i key.pem user#server
I now have a server of my own and am trying to figure out how I can do this with my server so I can automate commands to my server via ssh.
I imagine that I need to generate this key on my server and copy it to my client machine. How do I generate this key?
On the client machine you wish to login from, run ssh-keygen. For a quick and easy key, just hit enter on all of the questions. This will create a key pair in ~/.ssh. Specifically, ~/.ssh/id_rsa is your private key (keep this one safe), and ~/.ssh/id_rsa.pub is your public key (okay to distribute).
Copy your public key (~/.ssh/id_rsa.pub) onto the server that you wish to login to (e.g. scp ~/.ssh/id_rsa.pub me#myserver:. On the server, run cat id_rsa.pub >> .ssh/authorized_keys. To make sure that it has the correct permissions, you can run chmod 644 ~/.ssh/authorized_keys. Also, you can now delete the id_rsa.pub file that you copied over.
That's it! You should have password-less login from client to server. You must repeat the process with client and server swapped if you want password-less login from server to client.
Notes:
If the ~/.ssh directory does not exist on your server, the best way to create it is to ssh from the server to some other machine (e.g. the client). This will ensure that it has the correct permissions.
If you are paranoid about someone getting access to the client, you can password protect the key (one of the prompts when running ssh-keygen), but then you will have to enter that password every time you log in. The solution to this problem is to use ssh-agent.
Related
I am trying to configure a SSH Key-Based Authentication and after i created one, i want to copy the SSH Public Key to my server. When i give the following command on git bash : ssh-copy-id username#remote_host , i am asked for a password.
remote_host must be the floating_ip of the VM that i am trying to connect to ?
Which password should i type in ?
It would be really helpful if you could answer my questions.
On the first SSH operation (here an ssh-copy-id), you would need the password of the remote account, in order for the command to add your public kay to said remote user account ~/.ssh/authorized_keys.
Only then subsequent SSH commands would work without asking for password (only passphrase, if your private key is passphrase-protected, and if you have not added the private key to an ssh agent, for caching said passphrase).
I am trying to SSH into the server as part of the deployment job in CircleCI
ssh -oStrictHostKeyChecking=no $DEV_DROPLET_USER#$DEV_DROPLET_IP
I have my SSH private key for the user on this server loaded into CircleCI but everytime I run the job, I get this output
Warning: Permanently added '$host' (ECDSA) to the list of known hosts.
<$user>#<$host>'s password:
How can I stop it prompting me for the password?
I have added the SSH key for this user to the SSH Agent on the server (these instructions)
For a passwordless ssh connection, you must:
put the private ssh key into a file in the directory $HOME/.ssh/ on the client computer connecting to the server (example : $HOME/.ssh/MyServer)
copy the public ssh key into the file $HOME/.ssh/authorized_keys on the server
have writing permission on the file $HOME/.ssh/known_hosts on the client computer
The sshd service is normally already configured to accept key based authentication.
From the client computer, you can now do a passwordless connection ssh -i $HOME/.ssh/MyServer $DEV_DROPLET_USER#$DEV_DROPLET_IP
Of course, on the client computer your $DEV_DROPLET_USER must have appropriate permissions for accessing the ssh related files.
You don’t need to do anything with the ssh agent, on the client or on the server.
Late reply, but I hope it helps somebody else in the future.
Assuming you followed these instructions in the CircleCI docs, then the private key will automatically be copied to the machine being used by CircleCI when the add_ssh_keys step is run.
Make sure one the server you are trying to SSH into, the public key generated (in ~/.ssh/id_rsa.pub or something similar) is copied to the ~/.ssh/authorized_hosts file on the same server. This crucial step is what allows anybody with the private key (CircleCI) to be allowed into the server.
I'm sorry to have to ask this question, but I feel like I've tried every answer so far on SO with no luck.
I have my local machine and my remote server. Jenkins is up and running on my server.
If I open up terminal and do something like scp /path/to/file user#server:/path/to/wherever then my ssh works fine without requiring a password
If I run this command inside of my Jenkins job I get 'Host Key Verification Failed'
So I know my SSH is working correctly the way I want, but why can't I get Jenkins to use this SSH key?
Interesting thing is, it did work fine when I first set up Jenkins and the key, then I think I restarted my local machine, or restarted Jenkins, then it stopped working. It's hard to say exactly what caused it.
I've also tried several options regarding ssh-agent and ssh-add but those don't seem to work.
I verified the local machine .pub is on the server in the /user/.ssh folder and is also in the authorized keys file. The folder is owned by user.
Any thoughts would be much appreciated and I can provide more info about my problem. Thanks!
Update:
Per Kensters suggestion I did su - jenkins, then ssh server, and it asked me to add to known hosts. So I thought this was a step in the right direction. But the same problem persisted afterward.
Something I did not notice before I can ssh server without password when using my myUsername account. But if I switch to the jenkins user, then it asks me for my password when I do ssh server.
I also tried ssh-keygen -R server as suggested to no avail.
Try
su jenkins
ssh-keyscan YOUR-HOSTNAME >> ~/.ssh/known_hosts
SSH Slaves Plugin doesn't support ECDSA. The command above should add RSA key for ssh-slave.
Host Key Verification Failed
ssh is complaining about the remote host key, not the local key that you're trying to use for authentication.
Every SSH server has a host key which is used to identify the server to the client. This helps prevent clients from connecting to servers which are impersonating the intended server. The first time you use ssh to connect to a particular host, ssh will normally prompt you to accept the remote host's host key, then store the key locally so that ssh will recognize the key in the future. The widely used OpenSSH ssh program stores known host keys in a file .ssh/known_hosts within each user's home directory.
In this case, one of two things is happening:
The user ID that Jenkins is using to run these jobs has never connected to this particular remote host before, and doesn't have the remote host's host key in its known_hosts file.
The remote host key has changed for some reason, and it no longer matches the key which is stored in the Jenkins user's known_hosts file.
You need to update the known_hosts file for the user which jenkins is using to run these ssh operations. You need to remove any old host key for this host from the file, then add the host's new host key to the file. The simplest way is to use su or sudo to become the Jenkins user, then run ssh interactively to connect to the remote server:
$ ssh server
If ssh prompts you to accept a host key, say yes, and you're done. You don't even have to finish logging in. If it prints a big scary warning that the host key has changed, run this to remove the existing host from known_hosts:
$ ssh-keygen -R server
Then rerun the ssh command.
One thing to be aware of: you can't use a passphrase when you generate a key that you're going to use with Jenkins, because it gives you no opportunity to enter such a thing (seeing as it runs automated jobs with no human intervention).
i write a script to ssh to a server in a loop using public key. However, because of some reason my public key was not correctly copied to the login server. So, i will be hanged at servers with fault public key. the situation can be exampled like below:
i use eval /usr/local/bin/ssh-attach on my desktop to record the passphrase corresponging to private file A when login to the remote servers
however, serverA have added A.pub corresponding to private key file A to authorized_keys file
i have a private key file B on my desktop, so when trying to ssh login serverA it will hang with a prompt to ask passphrase.
Does ssh have some params to config to bypass this situation?
You can use the -i option to specify the key you want the ssh to use.
ssh -i path/to/key/file user#example.com
or you can add the equivalent setting to your ssh config file
Host Example
User john
IdentityFile /path/to/file
The target server is a relatively clean install of Ubuntu 14.04. I generated a new ssh key using ssh-keygen and added it to my server using ssh-copy-id. I also checked that the public key was in the ~/.ssh/authorized_keys file on the server.
Even still, I am prompted for a password every time I try to ssh into the server.
I noticed something weird however. After I log into my first session using my password, the next concurrent sessions don't ask for a password. They seem to be using the ssh key properly. I've noticed this behaviour on two different clients (Mint OSX).
Are you sure your SSH key isn't protected by a password? Try the following:
How do I remove the passphrase for the SSH key without having to create a new key?
If that's not the case, it may just be that ssh is having trouble locating your private key. Try using the -i flag to explicitly point out its location.
ssh -i /path/to/private_key username#yourhost.com
Thank you Samuel Jun for the link to help.ubuntu.com - SSH Public Key Login Troubleshooting !
Just a little caveat:
If you copy your authorized keys file outside your encrypted home directory please make sure your root install is encrypted as well (imho Ubuntu still allows for unencrypted root install coupled with encryption of the home directory).
Otherwise this defeats the whole purpose of using encryption in the first place ;)
If this is happening to you on Windows (I'm on Windows 10)
Try running the program that you're trying to connect via ssh to the server as administrator.
For me I was using powershell with scoop to install a couple of things so that I could ssh straight from it. Anyway... I ran PowerShell as admin and tried connecting again and it didn't ask for my password.
For LinuxSE
Check the SE context with
% ls -dZ ~user/.ssh
Must contain unconfined_u:object_r:ssh_home_t:s0
If not, that was the problem , as root run
# for i in ~user/.ssh ~user/.ssh/*
do
semanage fcontext -a -t ssh_home_t $i
done
# restorecon -v -R ~user/.ssh
It looks like it's related to encryption on your home directory and therefore the authorized_keys file cannot be read.
https://unix.stackexchange.com/a/238570
Make sure your ssh public key was copied to the remote host in the right format. If you open the key file to edit it should read 1 line.
Basically, just do ssh-copy-id username#remote. It will take care of the rest.