Not able to "git pull" - Host key verification failed - linux

Question

I've got root access to our production server and I want to deploy the latest version in git to the server but I'm running into the error below when I "git pull" on the folder I want to update.
I've browsed around a bit, but can't find a clear answer on what to do..
The staging server runs on the same machine, but just in a different folder and when I pull on that folder it all goes fine.
I'm not very experienced when it comes to Linux, so please help me out with a clear answer on how to fix :-)
Otherwise I have access to anything I need
p.s.
This has worked in the past, so I'm assuming it's got something to do with the SSH key
Error:
###########################################################
# WARNING: POSSIBLE DNS SPOOFING DETECTED! #
###########################################################
The ECDSA host key for www.site.org has changed,
and the key for the corresponding IP address x.x.x.x
is unknown. This could either mean that
DNS SPOOFING is happening or the IP address for the host
and its host key have changed at the same time.
###########################################################
# WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! #
###########################################################
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
*************
Please contact your system administrator.
Add correct host key in /root/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /root/.ssh/known_hosts:1
remove with: ssh-keygen -f "/root/.ssh/known_hosts" -R gitlab.site.org
ECDSA host key for gitlab.site.org has changed and you have requested strict checking.
Host key verification failed.

Answer 1

In the log you see the following text:
(...)
Please contact your system administrator.
Add correct host key in /root/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /root/.ssh/known_hosts:1
remove with: ssh-keygen -f "/root/.ssh/known_hosts" -R gitlab.site.org
ECDSA host key for gitlab.site.org has changed and you have requested strict checking.
Host key verification failed.
So it is a matter of performing the command that is suggested there:
ssh-keygen -f "/root/.ssh/known_hosts" -R gitlab.site.org

Answer 2

Windows:
Go to /Users/Abhilash/.ssh/known_hosts and delete the contents in it and save.
Linux / Mac:
Go to ~/.ssh/
nano known_hosts
remove content inside and save ctrl+O
Note:
You will be promted to save the key while pushing again.

Answer 3

I have also faced the same issue after following these steps it worked for me.
For macOS:
Step 1: Go to Folder or use command+shift+g
Step 2: type "~/.ssh/"
Step 3: Open "known_hosts" file and Remove all the content
Step 4: Now Open terminal and pull from another branch, It will ask for password give your system password.
It will work surely.

Answer 4

All of the other answers introduce security risks.
This error appears because you have a record in your known_hosts file which says that the server should have a particular ssh key. But when you try to connect, the server has sent a different ssh key which does not match the one in your known_hosts file. Your particular error message says:
Offending ECDSA key in /root/.ssh/known_hosts:1
This means that the first line in the known_hosts file is different to what the remote server is sending.
The secure way to fix the issue is as follows:
Find out what the correct key fingerprint should be from a trustworthy source. e.g. Here you can find the correct fingerprints for GitHub and GitLab. (If your organisation self-hosts GitLab, you will need to talk to your administrator to get the ssh key fingerprints.)
CHECK that the existing fingerprint in your known_hosts file is correct.
You can run ssh-keygen -lf ~/.ssh/known_hosts (or /root/.ssh/known_hosts in your case) to generate SHA256 fingerprints from your known_hosts file. Your error message says that the problem is with the first key. Find the equivalent SHA256 fingerprint on GitHub or GitLab and check if it matches exactly.
e.g. Here is the output of the above command:
256 SHA256:HbW3g8zUjNSksFbqTiUWPWg2Bq1x8xdGUrliXFzSnUw gitlab.com (ECDSA)
and here is the ECDSA SHA256 fingerprint from the GitLab website:
HbW3g8zUjNSksFbqTiUWPWg2Bq1x8xdGUrliXFzSnUw
If the existing fingerprint from known_hosts matches the official fingerprint from the GitHub or GitLab website, then ssh has detected a Man in the Middle (MitM) attack. STOP. Do not connect to the server. Try connecting from a different internet connection. Talk to your administrator.
If the existing fingerprint in known_hosts does not match the official fingerprint, then either you were under a MitM attack previously, or the server hosting GitLab has changed its ssh keys. You can delete the fingerprint from your known_hosts file. (Note: Only delete the specific fingerprint which is causing trouble.) Next time you connect to GitLab, you will be prompted to add the new fingerprint to the known_hosts file.
The authenticity of host 'gitlab.com (172.65.251.78)' can't be established.
ECDSA key fingerprint is SHA256:HbW3g8zUjNSksFbqTiUWPWg2Bq1x8xdGUrliXFzSnUw.
Are you sure you want to continue connecting (yes/no/[fingerprint])?
Double-check that the fingerprint matches what is shown on the GitHub or GitLab website, then type yes or no accordingly.

Answer 5

Try replacing ssh with:
ssh -oStrictHostKeyChecking=no
since if the key hasn’t been accepted yet, then it will ask do you want to accept it yes/no. Alternatively, you can also do this in your CI file just before the SSH command:
echo "StrictHostKeyChecking no" >> ~/.ssh/config
courtesy:
https://forum.gitlab.com/t/error-host-key-verification-failed/77315/3

Answer 6

if you'd like to remove this message permanently you can edit your ssh config file (~/.ssh/config) to include:
Host {YOUR HOST HERE}
StrictHostKeyChecking no
UserKnownHostsFile /dev/null