Aug 12, 2019 SSH is a encrypted protocol which allows client system to communicate securely with a server. Steps to Set Up SSH Keys on Ubuntu 18.04 server. Dec 15, 2018 By now, you probably know you should be using keys instead of passwords. This article details how to setup password login using ED25519 instead of RSA for Ubuntu 18.04 LTS. Why SSH Keys Are Needed. Https magesy. be vst- vsti- tags mixmeister. A key is a physical (digital version of physical) access token that is harder to steal/share. We use keys in ssh servers to help increase security.
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Introduction
Throughout this tutorial you will learn how to configure a basic level of security on a brand new Vultr VC2 virtual machine running Ubuntu 18.04.
Prerequisites
- A Vultr account, you can create one here
- A new Ubuntu 18.04 Vultr VM
Create and modify a user
The first thing we are going to do is create our new user that we will be using to log into the VM:
Note:It is recommended to use a unique username that will be difficult to guess. Most bots will default to try
root
, admin
, moderator
, and similar.You will be prompted for a password here. It is strongly Free mac microsoft office 2011. recommended that you use a strong alpha numeric password. Fa premier league manager 2002 torrent fifa 07. After that, follow the prompts on your screen and when it asks you if the information is correct just press Y.
Once that new user is added we will need to give that user sudo permissions so we can execute commands from the user on behalf of the root user:
Once you have given your user sudo permissions switch to your new user:
Generate and configure an SSH key
To generate the SSH key, please follow this doc.
Once you have generated your new SSH key, copy your public key. It should look like the following:
Configure your users directory
Navigate to your users home directory if you are not already in it:
$HOME
is the environment variable for your users home directory. This is automatically set when the new user is created.While in our home directory we are going to place another directory inside it. This directory will be hidden from other users on the machine, except root and the user who owns the directory. Create the new directory and restrict its permissions with the following commands:
Now we are going to open a file in
.ssh
called authorized_keys
. This is the universal file that OpenSSH looks for. You can change the name of this inside the OpenSSH config, /etc/ssh/sshd_config
, if the need arises.Use your favorite editor to create the file. This tutorial will use nano:
Copy and paste your ssh key into the
authorized_keys
file that we have opened. Once the public key is inside you can save the file by pressing CTRL + O. Make sure the appropriate file path shows up:
If it is the right file path just press ENTER, otherwise, make necessary changes to match the example above. Then exit the file with CTRL + X.
Now we are going to restrict access to the file:
Exit our created user and go back to the root user:
Disabling password authentication
We can now disable password authentication to the server, that way login will require an ssh key. It is important to note that if you disable password authentication and the public key was not installed correctly you will lock yourself out of your server. It is recommended that you test the key first before even logging out of your root user.
We are currently logged into our root user, so we are going to edit the
sshd_config
:We are going to search for 3 values to make sure that OpenSSH is configured properly.
PasswordAuthentication
PubkeyAuthentication
ChallengeResponseAuthentication
We can find these values by pressing CTRL + W.
The values should be set to the following:
If the values are commented out, remove the
#
at the beginning of the line and make sure that the values of those variables are as shown above. Once you have changed those variables, save and exit your editor, with CTRL + O, ENTER and finally CTRL + X.Now we are going to reload
sshd
with the following command:Now we can test the login. Make sure you have not logged out of your root session yet, and open up a new ssh window and connect with your ssh key linked to the connection.
In PuTTY this is under
Connection
-> SSH
-> Auth
.Browse to find your private key for authentication, as you should have saved it when creating the ssh key.
Connect to your server with the private key as your authentication. You will now be logged in to your Vultr VC2 virtual machine.
Note: Free download indesign cs6 for mac. If you added a passphrase while generating the ssh key you will be prompted for one. This is completely different from your actual user's password on the virtual machine.
Setup a basic firewall
Configure UFW
First we are going to start by installing UFW if it is not already on the virtual machine. A good way to check is with the following command:
If UFW is installed, it will output
Status:inactive
. If it is not installed, you will be instructed to do so.We can install it with this command:
Now we are going to allow SSH port
22
in our firewall:Alternatively, you can allow OpenSSH:
Either one of the commands above will work.
Now that we have allowed the port through our firewall we can enable UFW:
You will be asked if you are sure you want to perform this operation. Typing
y
followed by ENTER will enable the firewall:Note:If you did not allow OpenSSH or Port 22, you will lock yourself out of your virtual machine. Make certain that one of these is allowed before enabling UFW.
Once the firewall is enabled, you will still be connected to your instance. We are going to double check our firewall now with the same command as before: https://cacoarhinin.tistory.com/7.
You will see something similar to the following output:
Configuring the Vultr firewall
To further secure our server we are going to use our Vultr Firewall. Log in to your account. Once logged in you will navigate to the firewall tab located towards the top of your screen:
Now we are going to add a new firewall group. This will allow us to specify which ports can even reach our UFW firewall, providing us with a double layer of security:
Vultr will now ask you what you are going to name your firewall using the 'Description' field. Make sure you describe what the servers under this firewall group will be doing, for easier future administration. For the sake of this tutorial we are going to name it
test
. You can always change the description later if you would like.First we are going to need to get our IP address. The reason we are doing this directly is that if your IP address is not static and is constantly changing, you can simply log in to your Vultr account and change the IP address.
That is also why we did not require the IP address on the UFW firewall. Plus it limits the use of your virtual machine's firewall from filtering out all the other ports and just lets the Vultr firewall handle it. This limits the strain of overall traffic filtering on your instance.
Free product key generator windows 10. Use Vultr's network looking glass to find your IP address.
So now that we have our IP address we are going to add an IPV4 Rule to our newly created firewall:
Once you have the IP address entered, click the
+
symbol to add your IP address to the firewall.Your firewall group will look like the following:
https://newqa137.weebly.com/fmrte-2012-activation-key-generator.html. Now that we have our IP properly binded in the Firewall group, we need to link our Vultr Instance. On the left hand side you will see a tab that says 'Linked Instances':
![Ubuntu 18.04 ssh connection refused Ubuntu 18.04 ssh connection refused](/uploads/1/3/3/8/133819650/700338889.png)
Ubuntu 18.04 Ssh Connection Refused
Once on the page you will see a drop down with a list of your server instances:
Click the drop down and select your instance. Then, when your ready to add the instance to the firewall group click the
+
symbol.Congratulations, you have successfully secured your Vultr VC2 Virtual Machine. This gives you a good basis for a very basic security layer without the worry of someone trying to brute-force your instance.
I![18.04 18.04](/uploads/1/3/3/8/133819650/202359144.png)
Introduction: OpenSSH is a free and open source client/server technology for secure remote login. It is an implementation of the SSH protocol. OpenSSH divided into sshd (server) and various client tools such as sftp, scp, ssh and more. One can do remote login with OpenSSH either using password or combination of private and public keys named as public key based authentication. It is an alternative security method for user passwords. This method is recommended on a VPS, cloud, dedicated or even home-based server or laptop. This page shows how to set up SSH keys on Ubuntu 18.04 LTS server.
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Ubuntu 18.04 Setup SSH Public Key Authentication
The procedure to set up secure ssh keys on Ubuntu 18.04: Paypal money adder ultimate activation key generator for city car driving.
- Create the key pair using ssh-keygen command.
- Copy and install the public key using ssh-copy-id command.
- Add yourself to sudo admin account on Ubuntu 18.04 server.
- Disable the password login for root account on Ubuntu 18.04.
Sample set up for SSH Keys on Ubuntu 18.04
Where,
- 202.54.1.55 – You store your public key on the remote hosts and you have an accounts on this Ubuntu Linux 18.04 LTS server.
- Linux/macbook laptop – Your private key stays on the desktop/laptop/computer (or local server) you use to connect to 202.54.1.55 server. Do not share or give your private file to anyone.
In public key based method you can log into remote hosts and server, and transfer files to them, without using your account passwords. Feel free to replace 202.54.1.55 and client names with your actual setup. Enough talk, let’s set up public key authentication on Ubuntu Linux 18.04 LTS.
How to create the RSA/ed25519 key pair on your local desktop/laptop
Open the Terminal and type following commands if .ssh directory does not exists:
Next generate a key pair for the protocol, run:
OR
These days ED25519 keys are favored over RSA keys when backward compatibility is not needed:
$ mkdir -p $HOME/.ssh
$ chmod 0700 $HOME/.ssh
Next generate a key pair for the protocol, run:
$ ssh-keygen
OR
$ ssh-keygen -t rsa 4096 -C 'My key for Linode server'
These days ED25519 keys are favored over RSA keys when backward compatibility is not needed:
$ ssh-keygen -t ed25519 -C 'My key for Linux server # 42'
How to install the public key in Ubuntu 18.04 remote server
The syntax is as follows:
For example:
I am going to install ssh key for a user named vivek (type command on your laptop/desktop where you generated RSA/ed25519 keys):
ssh-copy-id your-user-name@your-ubuntu-server-name
ssh-copy-id -i ~/.ssh/file.pub your-user-name@your-ubuntu-server-name
For example:
## for RSA KEY ##
ssh-copy-id -i $HOME/.ssh/id_rsa.pub [email protected]
## for ED25519 KEY ##
ssh-copy-id -i $HOME/.ssh/id_ed25519.pub [email protected]
## install SSH KEY for root user ##
ssh-copy-id -i $HOME/.ssh/id_ed25519.pub [email protected]
I am going to install ssh key for a user named vivek (type command on your laptop/desktop where you generated RSA/ed25519 keys):
$ ssh-copy-id -i ~/.ssh/id_ed25519.pub [email protected]
Test it
Now try logging into the Ubuntu 18.04 LTS server, with ssh command from your client computer/laptop using ssh keys:
$ ssh your-user@your-server-name-here
$ ssh [email protected]
What are ssh-agent and ssh-add, and how do I use them on Ubuntu 18.04?
To get rid of a passphrase for the current session, add a passphrase to ssh-agent (see ssh-agent command for more info) and you will not be prompted for it when using ssh or scp/sftp/rsync to connect to hosts with your public key. The syntax is as follows:
Type the ssh-add command to prompt the user for a private key passphrase and adds it to the list maintained by ssh-agent command:
Enter your private key passphrase. Now try again to log into [email protected] and you will NOT be prompted for a password:
$ eval $(ssh-agent)
Type the ssh-add command to prompt the user for a private key passphrase and adds it to the list maintained by ssh-agent command:
$ ssh-add
Enter your private key passphrase. Now try again to log into [email protected] and you will NOT be prompted for a password:
$ ssh [email protected]
How to disable the password based login on a Ubuntu 18.04 server
Login to your server, type:
Now login as root user:
OR
Edit sshd_config file:
OR
Find PermitRootLogin and set it as follows:
Save and close the file. I am going to add a user named vivek to sudoers group on Ubuntu 18.04 server so that we can run sysadmin tasks:
Restart/reload the sshd service:
You can exit from all session and test it as follows:
## client commands ##
$ eval $(ssh-agent)
$ ssh-add
$ ssh [email protected]
Now login as root user:
$ sudo -i
OR
$ su -i
Edit sshd_config file:
# vim /etc/ssh/sshd_config
OR
# nano /etc/ssh/sshd_config
Find PermitRootLogin and set it as follows:
PermitRootLogin no
Save and close the file. I am going to add a user named vivek to sudoers group on Ubuntu 18.04 server so that we can run sysadmin tasks:
# adduser vivek sudo
Restart/reload the sshd service:
# systemctl reload ssh
You can exit from all session and test it as follows:
$ ssh [email protected]
## become root on server for sysadmin task ##
$ sudo -i
How do I add or replace a passphrase for an existing private key?
To to change your SSH passphrase type the following command:
$ ssh-keygen -p
How do I backup my existing private/public SSH keys
Just copy files to your backup server or external USB pen/hard drive:
How do I protect my ssh keys?
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- Always use a strong passphrase.
- Do not share your private keys anywhere online or store in insecure cloud storage or gitlab/github servers.
- Restrict privileges of the account.
Tip: Create and setup an OpenSSH config file to create shortcuts for servers
See how to create and use an OpenSSH ssh_config file for more info.
How do I secure my OpenSSH server?
See “OpenSSH Server Best Security Practices” for more info.
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Conclusion
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You learned how to create and install ssh keys for SSH key-based authentication for Ubuntu Linux 18.04 LTS server. See OpenSSH server documents here and here for more info.
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