Generate New Ssh Host Key Debian

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How do I regenerate OpenSSH sshd server host keys stored in /etc/ssh/ssh_host_* files? Can I safely regenerate ssh host keys using remote ssh session as my existing ssh connections shouldn’t be interrupted on Debian or Ubuntu Linux? How do I regenerate new ssh server keys? How to regenerate new host keys on a Debian or Ubuntu Linux?
  • Run ssh-keygen(1) on your machine, and just hit enter when asked for a password. This will generate both a private and a public key. With older SSH versions, they will be stored in /.ssh/identity and /.ssh/identity.pub; with newer ones, they will be stored in /.ssh/idrsa and /.ssh/idrsa.pub.
  • May 27, 2010  Linux / UNIX: Generate SSH Keys; Install / Append SSH Key In A Remote Linux / UNIX Servers Authorizedkeys; Linux / Unix ssh-keygen: Create A Host Key File; OpenSSH Change a Passphrase With ssh-keygen command; How To Set up SSH Keys on a Linux / Unix System; How to fix: MacOS keep asking passphrase for ssh key after upgrade or reboots.

If you don't already have an SSH key, you must generate a new SSH key. If you're unsure whether you already have an SSH key, check for existing keys. If you don't want to reenter your passphrase every time you use your SSH key, you can add your key to the SSH agent, which manages your SSH keys and remembers your passphrase. I currently have an old SSH key uploaded on a server. The problem is I lost my /.ssh directory (with the original idrsa and idrsa.pub files). Consequently, I want to remove the old SSH key directly on the server and upload a new one. I am unable to ssh to a server that asks for a diffie-hellman-group1-sha1 key exchange method: ssh 123.123.123.123 Unable to negotiate with 123.123.123.123 port 22: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1 How to enable the diffie-hellman-group1-sha1 key exchange method on Debian 8.0?


[donotprint][/donotprint]To regenerate keys you need to delete old files and reconfigure openssh-server. It is also safe to run following commands over remote ssh based session. Your existing session shouldn’t be interrupted.

Generate New Ssh Host Key Debian Update


Debian Ssh Setup

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Why regenerate new ssh server keys?

Generate New Ssh Host Key Debian

Most Linux and Unix distribution create ssh keys for you during the installation of the OpenSSH server package. Activation key generator for autocad 2006. But it may be useful to be able re-generate new server keys from time to time. For example, when you duplicate VM (KVM or container) which contains an installed ssh package and you need to use different keys from cloned KVM VM guest/machine.

Steps to regenerate OpenSSH host keys on Linux

Let us see all steps

Step 1 – Delete old ssh host keys

Login as the root and type the following command to delete files on your SSHD server:
# /bin/rm -v /etc/ssh/ssh_host_*
Sample outputs:

Step 2 – Debian or Ubuntu Linux Regenerate OpenSSH Host Keys

Now create a new set of keys on your SSHD server, enter:
# dpkg-reconfigure openssh-server
Sample output:

You just regenerated new ssh server keys. You need to restart ssh server:
$ sudo systemctl restart ssh
OR
$ /etc/init.d/ssh restart

Step 3 – Update all ssh client(s) known_hosts files

Finally, you need to update ~/.ssh/known_hosts files on client computers, otherwise everyone will see an error message that read as follows:

Key

Either remove host fingerprint or update the file using vi text editor (command must be typed on client machine):
$ ssh-keygen -R remote-server-name-here
Now login using the ssh command:
$ ssh vivek@server1.cyberciti.biz

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Conclusion

You just regenerated OpenSSH Host Keys on a Debian or Ubuntu Linux using the dpkg-reconfigure command. For more info see the man page or this wiki page here:
$ man dpkg-reconfigure
$ man sshd

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How do I generate ssh RSA keys under Linux operating systems?
You need to use the ssh-keygen command as follows to generate RSA keys (open terminal and type the following command):
ssh-keygen -t rsa
OR
ssh-keygen
Sample outputs:

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The -t type option specifies the type of key to create. The possible values “rsa” or “dsa” for protocol version 2. The $HOME/.ssh stores the following two files:

  • $HOME/.ssh/id_rsa – Your private RSA key
  • $HOME/.ssh/id_rsa.pub – Your public RSA key

Generate New Ssh Host Key Debian Download

Please do not share keys file with anyone else. You can upload keys to remote server as follows:
ssh-copy-id userName@server2.nixcraft.net.in
Finally, you can login to remote server as follows:
ssh userName@server2.nixcraft.net.in
scp file.txt userName@server2.nixcraft.net.in:~/data2/

See also:

  • Howto Linux / UNIX setup SSH with DSA public key authentication (password less login)
  • sshpass: Login To SSH Server / Provide SSH Password Using A Shell Script
  • keychain: Set Up Secure Passwordless SSH Access For Backup Scripts

Generate New Ssh Host Key Debian Download

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