Use ssh to connect to AWS EC2 instance

1: Create a new key pair

1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2. In the navigation pane, choose Key Pairs.
3. Choose Create key pair.
4. For Key pair name, enter a name for the new key pair, and then choose Create key pair.
5. Your browser will download the private key file automatically. The private key file is automatically downloaded by your browser. The base file name is the name you specified as the name of your key pair, and the file name extension is .pem. Save the private key file in a safe place.
6. Choose Close.
7. Important: You can create a key pair only once. Be sure to save the private key file to your computer. You’ll need to provide the name of your key pair when you launch an instance and the corresponding private key each time you connect to the instance.

2: Connect to your instance

1. Open a terminal window.
2. Use the cd command to navigate to the directory where your private key file is located.
3. Use the following command to set the permissions of your private key file so that only you can read it:

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chmod 400 /path/my-key-pair.pem

4. Use the following command to connect to your instance. Replace ec2-user with the appropriate user name for your AMI.

• For Amazon Linux 2 or the Amazon Linux AMI, the user name is ec2-user.
• For a CentOS AMI, the user name is centos.
• For a Debian AMI, the user name is admin.
• For a Fedora AMI, the user name is ec2-user or fedora.
• For a RHEL AMI, the user name is ec2-user or root.
• For a SUSE AMI, the user name is ec2-user or root.
• For an Ubuntu AMI, the user name is ubuntu. Here my OS is Ubuntu.
• Otherwise, if ec2-user and root don’t work, check with your AMI provider.

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ssh -i /path/my-key-pair.pem user_name@ip_address

3: (Optional) Connect to your instance using a password

1. Open a terminal window.
2. Use the following command to connect to your instance.

   1	ssh user_name@my-instance-ip

I meet Permission denied (publickey) error.

To fix it.

Step1: Firstly I need to use the previous command to connect to my instance.

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ssh -i /path/my-key-pair.pem user_name@ip_address

Step2: Set up a password for the user using passwd command along with the username.

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sudo passwd ubuntu

Step 3: Edit sshd_config file.

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sudo vim /etc/ssh/sshd_config

Find the Line containing PasswordAuthentication parameter and change its value from no to yes.

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PasswordAuthentication yes

If you want to set up root login, find PermitRootLogin parameter and change its value from prohibit-password to yes

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PermitRootLogin yes

After this changes save file and exit.

Step 4: Restart the SSH service.

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service ssh restart ## for ubuntu

service sshd restart ## for centos

Step 5: Add the .pem file to Local ssh.

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chmod 400 /path/my-key-pair.pem
ssh-add -k /path/my-key-pair.pem

Step 6: Now you can connect to your instance using a password.

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ssh user_name@my-instance-ip