Host key verification failed ssh windows

You are connecting via the SSH protocol, as indicated by the ssh:// prefix on your clone URL. Using SSH, every host has a key. Clients remember the host key associated with a particular address and refuse to connect if a host key appears to change. This prevents man in the middle attacks.

The host key for domain.example has changed. If this does not seem fishy to you, remove the old key from your local cache by editing ${HOME}/.ssh/known_hosts to remove the line for domain.example or letting an SSH utility do it for you with

ssh-keygen -R domain.example

From here, record the updated key either by doing it yourself with

ssh-keyscan -t rsa domain.example >> ~/.ssh/known_hosts

or, equivalently, let ssh do it for you next time you connect with git fetch, git pull, or git push (or even a plain ol’ ssh domain.example) by answering yes when prompted

The authenticity of host 'domain.example (a.b.c.d)' can't be established.
RSA key fingerprint is XX:XX:...:XX.
Are you sure you want to continue connecting (yes/no)?

The reason for this prompt is domain.example is no longer in your known_hosts after deleting it and presumably not in the system’s /etc/ssh/ssh_known_hosts, so ssh has no way to know whether the host on the other end of the connection is really domain.example. (If the wrong key is in /etc, someone with administrative privileges will have to update the system-wide file.)

I strongly encourage you to consider having users authenticate with keys as well. That way, ssh-agent can store key material for convenience (rather than everyone having to enter her password for each connection to the server), and passwords do not go over the network.

If you’ve ever tried to connect to a remote server using ssh, and received an error message that says “Host key verification failed,” you know how frustrating it can be. This article will show you three ways to fix the problem.

What is a Host Key in SSH?

A Host key is a unique identifier that is used to verify the identity of a remote host. When you connect to a remote host, the Host key is verified against a list of known Host keys. If there is a match, the connection will be allowed to proceed. If there is not a match, the connection will be denied.

The Host key is also used to generate a cryptographic signature for each connection. This signature is used to verify the integrity of the data that is transferred between the client and server.

Understanding error message Host key verification failed

If you receive the error message “Host key verification failed”, it means that the key stored for the host you’re trying to connect to has changed. It is often caused by connecting to a different server than the one you originally connected to (for example, your server has been rebuilt by a new one).

Whenever we connect to a server via SSH, that server’s public key is stored in our home directory. The file is called known_hosts. 

This file is local to the user account and contains the known keys for remote hosts. These are collected from the hosts when connecting for the first time.

As with those keys stored in the file, ~/.ssh/known_hosts, these keys are used to verify the identity of the remote host, thus protecting against impersonation or man-in-the-middle attacks.

When we reconnect to the same server, the SSH connection will verify the current public key matches the one we have saved in our known_hosts file. If there is a match, the connection will proceed. If the match fails, ssh will fail with an error message Host key verification failed happens.

Example of Host key verification failed

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 RSA key sent by the remote host is x. Please contact your system administrator.
Add correct host key in /home/ec2-user/.ssh/known_hosts to get rid of this message.

Offending RSA key in /home/ec2-user.ssh/known_hosts:222 RSA host key for www.howtouselinux.com has changed and you have requested strict checking.Host key verification failed.

Methods to fix problem of Host key verification failed

Host key verification failed error occurs when the server’s host key does not match the key that was expected. This can happen when the server’s key has been changed, or when the key has been compromised. 

Here are three ways to fix this Host key verification failed error.

• Manually edit the “~/.ssh/known_hosts” file and remove the old key for the host you’re trying to connect to. This will allow you to connect to the new server without any problems.
• Use the “ssh-keygen -R” command to remove the old key from your “~/.ssh/known_hosts” file. This will allow you to connect to the new server without any problems.
• Use the “-o StrictHostKeyChecking=no” option when connecting to the server. This will prevent ssh from checking the “~/.ssh/known_hosts” file, and will allow you to connect to the new server without any problems.

Remove old host key info from known_hosts file

The easiest way to fix the problem of Host key verification failed is removing the old host key info and reconnect the server.

We can fix this issue with the following steps.

• Locate our known_hosts file
• open in a general text editor with vi /home/user/.ssh/known_hosts
• search the old host name and press “ESC dd” to delete the line.
• save the changes by pressing “esc” and typing “:wq!”.
• reconnect the server

Remove old host key info with ssh-keygen command

We can also remove the old host key with ssh-keygen command.

Open up a terminal session, and type one of the following

• ssh-keygen -R hostname
• ssh-keygen -R ipaddress
• ssh-keygen -f “/home/ec2-user.ssh/known_hosts” -R “192.168.0.106”

Disable SSH stricthostkeychecking option

The stricthostkeychecking option in SSH is a security feature that verifies the host key information for each connection. If there is a problem with the host key information, the connection will not be allowed to proceed. This option can be disabled, which will allow the connection to proceed even if there is a problem with the host key information.

• Open up a terminal window.
• Type in the following command: ssh -o StrictHostKeyChecking=no hostname

This command removes the old host key for the device in the known_hosts file and replaces old host key with the new host key.

Understanding SSH known_hosts File with Examples

For most of the cases, the error msg returned by the Linux would have told you what to do. For instance in the earlier answer:

my_mac:~ oivanche$ sudo ssh pi@192.168.0.45
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    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
SHA256:sx1Z4xyGY9venBP6dIHAoBj0VhDOo7TUVCE2xWXpzQk.
Please contact your system administrator.
Add correct host key in /var/root/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /var/root/.ssh/known_hosts:74
ECDSA host key for 192.168.0.45 has changed and you have requested strict checking.
Host key verification failed.

It says that the remote server host key has changed — therefore your previously stored local record DOES NOT MATCH any more. For security reasons the connection is not established.

The simplest solution would be just deleted the line mentioned (line 74) in your local pc in /var/root/.ssh/known_hosts by

sudo nano /var/root/.ssh/known_hosts

You would want to deleted the line mentioned ONLY. No easier way just use your keyboard cursor and backspace or delete keys.

Once deletion is done, save it by command Ctrl+o and quit the file by command Ctrl+x.

Now reconnect to your host via ssh, using something like this:

ssh -i /Users/ben/document/key.pem root@192.168.0.45

where /Users/ben/document/key.pem is your server’s key pair you had set to use (can’t find it anymore? go to the hosting site to regenerate one) and 192.168.0.45 is your remote server IP you are connecting to.

When prompted with something like are you sure you want to add the host key permanently to this machine? type yes. Then you have updated your local key for connecting to the remote server for good.

Hope this clarifies and helps.

Are you getting Host key verification failed sftp error?

Often, the users may get this error while attempting to connect using SFTP to the host server.

Unfortunately, the error occurs due to the mismatch of the private key from the list of known hosts files, which contains the host key.

At Bobcares, we often get requests from our customers to fix an error message Host key verification failed sftp as part of our Server Management Services.

Today, let’s get into the details on how our Support Engineers fix this error.

What is Host key verification failed sftp error?

SFTP is a secure version of the File Transfer Protocol, which facilitates data access and transfer over a Secure Shell (SSH) data stream.

By default, it uses the unique host key for verifying the exact server. This error occurs due to the mismatch of key verified from the ~/.ssh/known_hosts file.

While trying to connect the host server via sftp protocol, the user may get the following.

Initially, when the customer connects to a server via SSH, the public host key of the client has been saved to the ~/.ssh/known_hosts file.

The next time when users connect to the remote server, the client compares this key to the one that the server supplies.

After that, a connection will establish when the key matches, otherwise the Host key verification failed sftp error will pop up.

How to fix Host key verification failed sftp

Usually, our Support Engineers fix the error by removing the old key from the ~/.ssh/known_hosts file. Removal of the old key is either done manually or by using the ssh-keygen command.

1. Manual removal of key

One of our customers approached us with a problem with file transfer. He received an error when he tried to upload a file via SFTP to another system.

The error said Host key verification failed sftp.

Normally, all the keys are available in the file ~/. ssh/known_hosts. The file known_hosts will be found in the home directory of its user. This error happens due to a mismatch of the private key from the list of known hosts files.

The fix involves the manual removal of the offending key from the file.

To fix the error, we opened the ~/.ssh/known_hosts file and removed the entry from the known_hosts file.

Thus, it resolved the problem of the customer and he could upload files via sftp.

2. ssh-keygen command

Similarly, when a key mismatch occurs, we use the ssh-keygen command to remove the old key from the file ~/.ssh/known_hosts.

ssh-keygen -R [hostname|IP address]

After the removal of the key by using any of this method, the remote server asks for a confirmation to add the new key to the ~/.ssh/known_host file. It indicates the successful removal of the old key.

3. Problem with root user’s key

Often, many customers find problems while transferring files from one server to another. They may have the following error when they try to transfer the file.

"Could not open location 'sftp://dad@192.168.0.3/home/dad/Desktop/Desktop-Laptop%20swap%20file' Host key verification failed"

Sometimes, this occurs when the root user’s key mismatch with the key that already stored in the known_host file. Then we have to remove the old key entry from /root/.ssh/known_hosts file.

So our Support Engineers removed the old key by using the ssh-keygen command. After that, the user was easily able to transfer the files without any error.

[Need more help to solve sftp errors?- We’ll help you.]

Conclusion

In short, Host key verification failed sftp error mainly occurs when the server’s public host key mismatches with the key in the known_hosts file. Today, we saw how our Support Engineers fix this error for our customers.

var google_conversion_label = «owonCMyG5nEQ0aD71QM»;

При использовании ssh-сервера вы можете столкнуться с одной из распространенных ошибок: «Host Key Verification Failed». Чтобы понять, почему возникает эта ошибка, давайте сначала разберемся, как ssh устанавливает соединение.

Когда вы пытаетесь подключиться к удаленному серверу, сервер просит вас подтвердить, пытаетесь ли вы установить соединение с правильным сервером.

Если вы наберете «да», клиент добавит открытый ключ хоста в файл «.ssh/known_hosts». После добавления ключа удаленного сервера в следующий раз, когда вы попытаетесь подключиться к тому же серверу, клиент сравнит ключи с ключами, хранящимися в файле «known_hosts».

Вы не получите никаких предупреждений, если ключ присутствует в файле «known_hosts». Сервер будет подключен сразу.

Почему возникает ошибка «Host Key Verification Failed»

Основная причина, вызывающая ошибку Host Key Verification Failed», заключается в том, что ключ удаленного хоста был изменен и больше не тот, который хранится в файле «known_hosts». Ключ обычно меняется, когда серверы перестраиваются, и вы получаете сообщение об ошибке, как показано ниже:

Как исправить ошибку «Host Key Verification Failed»

Чтобы исправить эту ошибку, нам нужно удалить неверный ключ из файла «known_hosts», находящегося в нашей системе в каталоге «.ssh». Ошибка дает вам IP-адрес удаленного сервера и номер строки, в которой хранится ключ в файле «known_hosts».

В приведенной выше ошибки, «/home/user/.ssh/known_hosts:7», то «: 7» является задеть номер строки. Ниже перечислены несколько подходов к исправлению этой ошибки:

Способ 1:

Первый способ исправить эту ошибку – использовать команду sed. Команда «sed» используется для изменения текстовых файлов для поиска, добавления или удаления чего-либо из файлов. Мы используем его для удаления хоста-нарушителя:

$ sed -i '7d' ~.ssh/known_hosts

Если «7» – это номер строки, показанный в приведенной выше ошибке, ваш номер строки может быть другим; убедитесь, что вы используете правильный номер строки. Команда удалит неправильную строку из файла «known_hosts» и решит проблему.

Способ 2:

Второй подход – открыть файл «known_hosts» в любом редакторе:

$ nano.ssh/known_hosts

И вручную удалите оскорбительную строку и сохраните файл.

Способ 3:

Третий метод – удаление сервера с помощью команды «ssh-keygen». Следуйте синтаксису, указанному ниже:

$ ssh-keygen -R [IP_ADDRESS]

Например, чтобы удалить ключ хоста «192.168.10.116», используйте:

$ ssh-keygen -R 192.168.10.116

Заключение

Ошибка проверки ключа хоста возникает, когда ключ удаленного сервера изменяется, а клиент не проверяет его по сохраненным ключам. Ключи сервера хранятся в файле «known_hosts» на стороне клиента, и после установления соединения клиент проверяет ключ, сравнивая его с ключами, хранящимися в файле «known_host», и в случае сбоя вы получаете “Host key verification failed”.

Чтобы исправить это, удалите хост-нарушитель из файла «known_hosts». В этой статье упоминаются три различных метода удаления вредоносного хоста, и любой метод может использоваться для устранения этой ошибки.