An attacker could impersonate the server, but never connect to the real server. With password authentication any server you connect to (legitimate or not) will see the password. For those reasons an ssh key without password is a lot more secure than just storing the password. Finally append a's new public key to b@B.ssh/authorizedkeys and enter b's password one last time: a@A: cat.ssh/idrsa.pub ssh b@B 'cat.ssh/authorizedkeys' b@B's password: From now on you can log into B as b from A as a without password: a@A: ssh b@B A note from one of our readers: Depending on your version of SSH you might also.

SSH (Secure SHELL) is an open source and most trusted network protocol that is used to login into remote servers for execution of commands and programs. It is also used to transfer files from one computer to another computer over the network using secure copy (SCP) Protocol.

In this article we will show you how to setup password-less login on RHEL/CentOS 7.x/6.x/5.x and Fedora using ssh keys to connect to remote Linux servers without entering password. Using Password-less login with SSH keys will increase the trust between two Linux servers for easy file synchronization or transfer.

My Setup Environment

If you are dealing with number of Linux remote servers, then SSH Password-less login is one of the best way to automate tasks such as automatic backups with scripts, synchronization files using scp and remote command execution.

In this example we will setup SSH password-less automatic login from server 192.168.0.12 as user tecmint to 192.168.0.11 with user sheena.

Step 1: Create Authentication SSH-Kegen Keys on – (192.168.0.12)

First login into server 192.168.0.12 with user tecmint and generate a pair of public keys using following command.

Create SSH RSA Key

Step 2: Create .ssh Directory on – 192.168.0.11

Use SSH from server 192.168.0.12 to connect server 192.168.0.11 using sheena as user and create .ssh directory under it, using following command.

Step 3: Upload Generated Public Keys to – 192.168.0.11

Use SSH from server 192.168.0.12 and upload new generated public key (id_rsa.pub) on server 192.168.0.11 under sheena‘s .ssh directory as a file name authorized_keys.

Upload RSA Key

Step 4: Set Permissions on – 192.168.0.11

Ssh Connect Without Password

Due to different SSH versions on servers, we need to set permissions on .ssh directory and authorized_keys file.

Step 5: Login from 192.168.0.12 to 192.168.0.11 Server without Password

From now onwards you can log into 192.168.0.11 as sheena user from server 192.168.0.12 as tecmint user without password.

SSH Remote Passwordless Login

You can login to a remote Linux server without entering password in 3 simple steps using ssky-keygen and ssh-copy-id as explained in this article.

ssh-keygen creates the public and private keys. ssh-copy-id copies the local-host’s public key to the remote-host’s authorized_keys file. ssh-copy-id also assigns proper permission to the remote-host’s home, ~/.ssh, and ~/.ssh/authorized_keys.

This article also explains 3 minor annoyances of using ssh-copy-id and how to use ssh-copy-id along with ssh-agent.

Step 1: Create public and private keys using ssh-key-gen on local-host

Step 2: Copy the public key to remote-host using ssh-copy-id

Note: ssh-copy-id appends the keys to the remote-host’s .ssh/authorized_key.

Step 3: Login to remote-host without entering the password

The above 3 simple steps should get the job done in most cases.

We also discussed earlier in detail about performing SSH and SCP from openSSH to openSSH without entering password.

If you are using SSH2, we discussed earlier about performing SSH and SCP without password from SSH2 to SSH2 , from OpenSSH to SSH2 and from SSH2 to OpenSSH.

Using ssh-copy-id along with the ssh-add/ssh-agent

/aes-256-key-generator-java.html. When no value is passed for the option -i and If ~/.ssh/identity.pub is not available, ssh-copy-id will display the following error message.

If you have loaded keys to the ssh-agent using the ssh-add, then ssh-copy-id will get the keys from the ssh-agent to copy to the remote-host. i.e, it copies the keys provided by ssh-add -L command to the remote-host, when you don’t pass option -i to the ssh-copy-id.

Bash Ssh Generate Key Login Without Password Windows 8 1

Three Minor Annoyances of ssh-copy-id

Following are few minor annoyances of the ssh-copy-id.

1. Default public key: ssh-copy-id uses ~/.ssh/identity.pub as the default public key file (i.e when no value is passed to option -i). Instead, I wish it uses id_dsa.pub, or id_rsa.pub, or identity.pub as default keys. i.e If any one of them exist, it should copy that to the remote-host. If two or three of them exist, it should copy identity.pub as default.
2. The agent has no identities: When the ssh-agent is running and the ssh-add -L returns “The agent has no identities” (i.e no keys are added to the ssh-agent), the ssh-copy-id will still copy the message “The agent has no identities” to the remote-host’s authorized_keys entry.
3. Duplicate entry in authorized_keys: I wish ssh-copy-id validates duplicate entry on the remote-host’s authorized_keys. If you execute ssh-copy-id multiple times on the local-host, it will keep appending the same key on the remote-host’s authorized_keys file without checking for duplicates. Even with duplicate entries everything works as expected. But, I would like to have my authorized_keys file clutter free.

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