To connect to an Amazon AWS EC2 instance from a CentOS or RHEL system using an SSH client, you will need to have the SSH client installed on your system, and you will need to have the private key file that was used to launch the EC2 instance.
First, make sure that the SSH client is installed on your system. On CentOS or RHEL, you can use the yum command to install the openssh-clients package, which includes the ssh command-line client. For example, to install the openssh-clients package, you would run the following command:
sudo yum install openssh-clients
Next, locate the private key file that was used to launch the EC2 instance. This file will typically have a .pem extension, and it should be stored in a secure location on your local system.
Once you have the private key file, you can use the ssh command to connect to the EC2 instance. The ssh command requires the private key file, the username to use for the SSH connection, and the public DNS or IP address of the EC2 instance. For example, to connect to an EC2 instance with the private key file mykey.pem, the username ec2-user, and the public DNS ec2-123-45-67-89.compute-1.amazonaws.com, you would run the following command:
ssh -i mykey.pem ec2-user@ec2-123-45-67-89.compute-1.amazonaws.com
This will connect to the EC2 instance using the specified private key file and username, and open an SSH terminal session.