On Ubuntu 14.04 I have a private key in:
~/.ssh/id_rsa
I have installed the public key on the server I wish to connect to and indeed when I run the following, I do connect as expected:
ssh me#my-server-ip.com
I then deleted the private key on the client but running the above command still connects me. This leads me to believe that the SSH binary is running in some kind of daemon mode wherein it is caching the private key in memory? Is that correct? Short of a reboot, how do I 'flush' SSH to stop using the private key. Thanks
Run the following command after removing ~/.ssh/id_rsa
ssh-add -D
This commando removes all cached ssh identities from the ssh-agent.
If you type ssh me#my-server-ip.com now, the password prompt will show.
You can check with ssh-add -L what identities the ssh-agent has cached.
I know I'm a little late to this party, but for the enlightenment of others...
It sounds like you have your private SSH key (identity) cached in ssh-agent. Now it is worth noting that ssh-agent does not retain the key cache over a reboot or logout/login cycle, although some systems depending on configuration may add your key during either of those processes. However, in your instance, a reboot or possibly a logout/login cycle would remove the private key from the agent's cache. This is because you have already removed the ~/.ssh/id_rsa file and it therefore cannot be re-initialized into the agent.
For everyone else who may not have yet deleted their ~/.ssh/id_rsa file(s) or if you don't want to reboot or logout/in right now the following should prove useful.
First, you will want to remove any ~user/.ssh/id_rsa files which you wish to no longer be cached by ssh-agent.
Next, verify that there are, in fact, identities still being held open in 'ssh-agent' by running the following command:
ssh-add -L
This will list the public key parameters of all identities that the agent has actively cached. (Note: ssh-add -l will instead list the fingerprints of all keys/identities that are actively cached.) For each that you would like to remove you should run the following:
ssh-add -d /path/to/matching/public/key/file
If you just want to clear out ALL keys/identities from the agent then run this instead:
ssh-add -D
At this point, the key(s) desired to be removed will be no longer accessible to the agent and with the actual identity file removed, there shouldn't' be any way possible for an attempted remote SSH connection with that user to connect without using a different authorization method if configured/allowed.
Related
In SourceTree I'm using OpenSSH as authentication and created + added my SSH keys (on Windows) like this:
ssh-keygen -t rsa -C "my#email.com"
(and entered filename, password etc)
Added the key to the SSH agent:
eval "$(ssh-agent)"
ssh-add id_rsa
Added the SSH key to GitLab using
cat id_rsa.pub to print my public key
Added the public key to SourceTree by "Tools > Add SSH key" followed by the password ("Tools > options > SSH client configuration" I've selected OpenSSH).
After these steps I'm able to push and pull code.
However, each time I restart SourceTree a terminal pops-up and I have to re-enter my password again*. How can I make SourceTree / the SSH agent remember this password?
ps. my keys are saved in a directory like /d/MyName/Gitlab/ instead of ~/.ssh/ but that shouldn't be a problem, right?
EDIT:
*The message shown in the terminal:
SourceTree is loading your SSH key into the agent for authentication Please enter your passphrase if prompted to do so Enter passphrase for D:\MyName\GitLab\.ssh\id_rsa:
EDIT2:
This solution didn't solve my problem either:
You can use the Windows OpenSSH ssh-agent to manage your keys.
The problem is that Sourcetree on windows wants to start its own instance of the ssh-agent instead of using the already running service. Even if you can get that to work it will still prompt for your key passphrase on startup because Sourcetree's ssh-agent process doesn't save your keys to the the Windows keychain.
There are heaps of instructions on how to use Pageant as your ssh agent, but that is not why you're here. You're here because you want to use the OpenSSH agent, with OpenSSH formatted keys, with passphrases but without being prompted for said passphrase all over the place.
The trick is to proxy all requests to Pageant through to your OpenSSH agent.
Install OpenSSH.
Start the ssh-agent service and set to automatic.
Add your private keys to the agent with
ssh-add <key_file>
Add your public keys to the hosts you want to authenticate with.
Test that you can authenticate via ssh:
ssh -T git#github.com
Your private keys will now be loaded when you log in to your Windows account and you won't have to provide passphrases ever again.
To allow programs and libraries such as Sourcetree, WinSCP and Fabric that normally use Pageant to instead have keys provided by the ssh-agent there is an awesome program https://github.com/ndbeals/winssh-pageant
Follow instructions to install winssh-pageant, schedule it as a task to start on windows startup.
Now all calls to Pageant's NamedPipe will be proxied to the OpenSSH agent.
The last step to get SourceTree working with OpenSSH is a bit counter-intuitive.
Go to Tools | Options | General and set the SSH Client to PuTTY/Plink and uncheck the "Automatically start SSH agent when Sourcetree opens".
I solved this issue following these steps:
Find the path to Pageant (in my case was in C:\Users\{my-user}\AppData\Local\SourceTree\app-3.3.8\tools\putty\pageant.exe)
Do Window key + R or type run in Windows bar
In the text box put shell:startup
Make a shortcut of your pageant and paste it in the window that just opened
Right click on the shortcut and click on Properties
In Shortcut tab, in target put your-sourcetree-pageant-path\pageant.exe id_rsa.ppk
In Start in put C:\Users\{my-user}\.ssh and click ok
Note that your id_rsa.ppk must be inside C:\Users\{my-user}\.ssh directory
If for some reason your id_rsa.ppk is protected by a passphrase and you are sure you won't have security issues. Just remove the passphrase.
To remove the id_rsa.ppk's passphrase, follow these steps
Open PuttyGen
Go to Conversions => Import key
Remove the passphrase
Save the private key & public key
Replace the protected id_rsa.ppk with the unprotected id_rsa.ppk
Hope that helped!
You manually start your agent and set environment variables in order for commands to find it.
Whenever you start your a command (like SourceTree) without those environment variables set, that command is not able to access the agent and therefore asks for your password.
Making your agent start on system startup should solve things.
If ssh cannot reach the agent it will also look into ~/.ssh/ therefor if you place you keys there it should work, too. (Have a look at man ssh.)
After did below test, the password never asked for me.
To test whether your SSH key was added correctly, run the following command in your terminal (replacing gitlab.com with your GitLab's instance domain):
ssh -T git#gitlab.com
The first time you connect to GitLab via SSH, you should verify the authenticity of the GitLab host that you're connecting to. For example, when connecting to GitLab.com, answer yes to add GitLab.com to the list of trusted hosts:
The authenticity of host 'gitlab.com (35.231.145.151)' can't be established.
ECDSA key fingerprint is SHA256:HbW3g8zUjNSksFbqTiUWPWg2Bq1x8xdGUrliXFzSnUw.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'gitlab.com' (ECDSA) to the list of known hosts.
NOTE: Note: For GitLab.com, consult the SSH host keys fingerprints, section to make sure you're connecting to the correct server. For example, you can see the ECDSA key fingerprint shown above in the linked section.
Once added to the list of known hosts, you should validate the authenticity of GitLab's host again. Run the above command once more, and you should only receive a Welcome to GitLab, #username! message.
If the welcome message doesn't appear, you can troubleshoot the problem by running ssh in verbose mode with the following command:
ssh -Tvvv git#gitlab.com
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).
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.
I did ssh-add. During the session it works fine, but when I exit and reconnect to the server with ssh it does not work anymore ssh-add -l says: no identities.
I do start the ssh-agent in my .bash_profile using eval $(ssh-agent).
Any ideas what I can do to keep the identities?
// EDIT
So here is my scenario. I am connecting to my web-space using ssh. I want to pull data from github using git pull. I added the connection to github and git pull works fine. But it asks for the passphrase. Doing a ssh-add adn adding the passphrase stops that, but only for the current session.
I have to start the ssh-agent using something like eval $(ssh-agent) because it does not autostart on the server.
The main problem I am having is, that I need a script to do the git pull which is invoked by a request from github, so I can not give it the passphrase.
If you're spawning the agent when your session starts, then it'll die when you disconnect. You could connect to a screen or byobu/tmux server which keeps the agent alive (you can skip an instance of bash if you connect like ssh user#hostname -t 'byobu').
Otherwise, have the agent come up when the machine boots so your session comings and goings don't affect it.
Edit: you can also forward your agent from your local machine. This works very well if you happen to have the same keys available on both machines. Try something like this in your ~/.ssh/config:
Host whatever
Hostname whatever.com
User username
ForwardAgent yes
You invoke this with ssh whatever, in case you are not familiar with that config file.
I need to create a script that automatically setup a ssh tunnel. I think that a dedicated ssh key without password is a good start but I couldn't find if this is possible and how to do it.
This key should have limited privileges (only set the tunnel up) but I need another private key (with a password) for myself.
Thanks !
Ok, I've found the answer.
First, ssh-keygen -f theNewPrivateKey otherwise it will overwrite the old private key.
Second, ssh -i theNewPrivateKey me#mycomputer the -i option changes the private key used for the authentication.
Now I can try my script.
Edit: how does my new key has limited privileges:
When copying the public key to $HOME/.ssh/authorized_keys2 file of the target computer, I added this:
command="sleep 99999999999" ssh-dss AAAAB3NzaC1kc3MA...
(+ the rest of the key)
Then the only command allowed is to wait forever.
Since the purpose of creating this key was to create a reverse ssh tunnel this should be fine.
I then create the tunnel:
ssh -T -R 7878:localhost:22 -i .ssh/mynewkey me#myhomecomputer
Finally I can log from my home computer:
ssh myworklogin#localhost -p7878
I hope that this does not have security issues. If this is a bad thing, please let me know !
Try the
ssh-keygen
command.
I had a similar situation where i had to synch a server content automatically without having to proivide the password in my robocopy script.
This Link helped me.