how to ssh without password

Let say you want to access to a machine with IP 192.168.1.10, and make sure you have
command ssh, ssh-keygen, ssh-copy-id.
First, generate the ‘key’, the key will be used to open the remote machine’s door.

ssh-keygen

You will see something like that

Enter file in which to save the key (/home/myname/.ssh/id_rsa):

Whatever it appears just press enter until it ends, press enter for passphase as well.
Okay, the ‘key’ will be generated, something looks like ~/.ssh/id_rsa.pub
Copy over the ‘key’ to remote machine, and enter your password

ssh-copy-id -i ~/.ssh/id_rsa.pub macspc@192.168.1.10

Done. Now you can ssh 192.168.1.10 with username macspc without password.

ssh macspc@192.168.1.10

What I Did

~? ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/brijith/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/brijith/.ssh/id_rsa.
Your public key has been saved in /home/brijith/.ssh/id_rsa.pub.
The key fingerprint is:
4b:71:39:69:36:13:0a:69:65:21:de:5f:24:b4:1c:b6 brijith@Newmegadisk
~? ssh-copy-id -i ~/.ssh/id_rsa.pub macpc@192.168.1.10
29
Password:
Now try logging into the machine, with "ssh 'macspc@192.168.1.10'", and check in:
.ssh/authorized_keys
to make sure we haven't added extra keys that you weren't expecting.

Now you can login through ssh with out a password

ssh macspc@192.168.1.10

It wont ask password any more.

If you want to launch application of the remote system in your PC using ssh use -X option of it

eg:

ssh -X macspc@192.168.1.10

and then give the application name you want to launch in resulting terminal
eg:

gedit&

This will launch gedit of remote system in your system

gedit