SSH Passwordless Authentication
| Posted by watashii | Filed under Software, Unix
This post shows how to use PuTTY (Windows) to login to a remote server (UNIX) over SSH without password.
Step 1 – Setting up the remote server (UNIX)
Login to the remote server using the normal username and password.
Ensure that no-one but the user can access the .ssh path and authorized_keys file within the user directory
$ cd ~
$ chmod 700 .ssh
$ chmod 600 .ssh/authorized_keys
In the .ssh directory, we will create a public/private key-pair which will form the basis for authetication between the client and server. Unix utility ssh-keygen will accept DSA or RSA (two commonly used key types) with a default 1024 bits key size. Follow the prompts and accept the default filename, and leave an empty passphase to create your passwordless login.
$ ssh-keygen -t dsa
Generating public/private dsa key pair.
Enter file in which to save the key (~/.ssh/id_dsa):
Enter passphrase (empty for no passphrase):
Your identification has been saved in ~/.ssh/id_dsa.
Your public key has been saved in ~/.ssh/id_dsa.pub.
The key fingerprint is:
21:15:5d:13:68:42:10:46:bd:fa:bd:b6:7c:5d:64:f1
You should now have the key-pair files named id_dsa.pub and id_dsa. Append the public key in authorized_keys as per below.
$ cat id_dsa.pub >> .ssh/authorized_keys
Step 2 – Generating the PuTTY private key (Windows)
You will need to transfer the id_dsa private key file on to the Windows client PC via SFTP (or various means). Launch the puttygen Windows utility, go to [File > Load private key], and open your private key.
Save private key without a passphrase, as shown below, and name the file with a .ppk extension.
Step 3 – Setting up the PuTTY client (Windows)
So now you have a PuTTy-generated private key .ppk file, we can now use this to PuTTy-login to the UNIX server without needing a password.
Open your PuTTy Windows client, and before you connect your session, select the .ppk private key you generated under [SSH > Auth].
Share:
Related Posts:
- BusinessObjects InfoView LDAP Authentication Error
- Oracle SQLPlus Query Output to a File
- Starting / Shutdown Oracle Database in Unix
Tags: authentication, passwordless, putty, ssh, unix
