Ssh – Not able to do password-free access to remote machine!

ssh

When I run

ravbholua@ravbholua-Aspire-5315:~$ rlogin 109.202.101.166

it promps me for password as below:

ravbholua@ravbholua-Aspire-5315:~$ rlogin 109.202.101.166
ravbholua@109.202.101.166's password:

To make password free access, I created a file /etc/hosts.equiv
in the remote machine (ravi.com) as below:

root@ravi:/etc# cat hosts.equiv
localhost
42.110.54.211
root@ravi:/etc#

But still whenever I run the above command to login to this remote
machine, it asks for password.

Additionally, I also created .rhosts file in my same like-to-like account
in remote machine in home dir. as below:

ravbholua@ravi:~$ cat .rhosts
localhost
42.110.54.211
ravbholua@ravi:~$

What may be the problem that I am not able to have password-free access.

One important point to be noted:
To know what's my internet IP address is, I got from the below two sites (both gave the same IP address)

http://www.ipchicken.com/
http://whatismyip.org/

You may please refer to the below link where I had asked for the same query but
couldn't get resolved.
not-able-to-do-password-free-access-to-remote-machine

Edit: I ran:

ravbholua@ravbholua-Aspire-5315:~$ sudo scp ~/.ssh/id_rsa.pub rs:.ssh/authorized_keys

as without sudo, it messaged:permission denied. Then I tried both 

sudo ssh rs

and 

ssh rs

Still I was prompted for password. I entered my remote server after entering password and found the file that was transferred in /root/.ssh as shown ahead.

root@ravi:~/.ssh# ls                             
authorized_keys known_hosts                                      
root@ravi:~/.ssh#

Please note rs is an alias for my remote server.

Best Answer

You can also use ssh to configure password-less login to a remote computer.

It is just (on computer a):

$ ssh-keygen # use an empty password!
$ scp ~/.ssh/id_rsa.pub computer_b:.ssh/authorized_keys

That's it.

Now you can do a

$ ssh computer_b

without having to enter a password.

You can optionally configure things like:

  • host alias for computer_b, e.g. to be able to enter ssh alias
  • set public-key authentication as default for that host/alias
  • allow only public-key authentication (for the sshd on computer_b)

Unless you can't use ssh, it seems to be much more convenient to setup than rlogin.

Plus, ssh protects you against main-in-the-middle attacks and eavesdropping.

Troubleshooting

Make sure that the ~/.ssh has the right permissions (on both systems) - i.e. is only accessible by your user - otherwise ssh ignores it. That means only rwx------ for the directory and rw------- for the files. Use ls -l and ls -ld to verify this.

Make sure that the remote ~/.ssh/authorized_keys contains the correct public key. Verify via:

$ ssh computer_b cat '~/.ssh/authorized_keys' # remote
$ cat ~/.ssh/id_rsa.pub # local

If the setup does not work like this, perhaps you have to explicitly configure the client side, i.e. adding something like this to .ssh/config:

Host computer_b
Hostname some_hostname
User juser
PreferredAuthentications publickey # makes testing easier
IdentitiesOnly yes
IdentityFile ~/.ssh/id_rsa.pub

For diagnosing issues it is also useful to add -v to ssh call, e.g.:

$ ssh -v computer_b
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