Setting SSH in unix

What is SSH

(SSH client) is a program for logging into a remote machine and for executing commands on a remote machine. It is intended to replace rlogin and rsh, and provide secure encrypted communications between two untrusted hosts over an insecure network. X11 connections and arbitrary TCP/IP ports can also be forwarded over the secure channel.

Login session and remote execution

When the user’s identity has been accepted by the server, the server either executes the given command, or logs into the machine and gives the user a normal shell on the remote machine. All communication with the remote command or shell will be automatically encrypted.

How to set up SSH to login from one server to another?

Let’s begin

First, install OpenSSH on two UNIX machines, Let us name them as Argon and Boron .

On each machine type ssh workingmachine.com(example) and make a connection with your regular password. This will create a .ssh dir in your home directory  with the proper perms.
On your primary machine where you want your secret keys to live (let’s say Argon), type
ssh-keygen -t dsa
This will prompt you for a secret passphrase. If this is your primary identity key, make sure to use a good passphrase. If this works right you will get two files called id_dsa and id_dsa.pub in your .ssh dir. Note: it is possible to just press the enter key when prompted for a passphrase, which will
make a key with no passphrase. This is a Bad Idea for an identity key, so try to avoid! See below for uses of keys without passphrases.

scp ~/.ssh/id_dsa.pub boron:.ssh/authorized_keys2
Copy the id_dsa.pub file to the other host’s .ssh dir with the name authorized_keys2.
Now boron is ready to accept your ssh key. How to tell it which keys to use? The ssh-add command will do it. For a test, type
ssh-agent sh -c ‘ssh-add < /dev/null && bash’
This will start the ssh-agent, add your default identity(prompting you for your passphrase), and spawn a bash shell. From this new shell you should be
able to:
ssh boron
This should let you in without typing a password or passphrase. Yuppie! You can ssh and scp all you want from this bash shell and not have to type any password or passphrase.

 

No related posts.

7 Responses to “Setting SSH in unix”

Leave a Reply


× seven = 14