• 02 Jan, 2026
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Passwordless SSH Configuration for Oracle RAC

Passwordless SSH Configuration for Oracle RAC-

Step-by-Step guide

Why Passwordless SSH?

During a RAC installation, the Grid Infrastructure (GI) software must be installed on all nodes. Instead of you logging into each server manually, the installer uses scp (secure copy) and ssh (secure shell) to push binaries and run configuration scripts. If SSH asks for a password, the installation will fail.

Prerequisites

Before starting, ensure the following are true for all nodes (e.g., racnode1 and racnode2):

• The oracle and grid users are created.

• The /home/oracle and /home/grid directories exist and have correct permissions.

• Hostnames are resolvable via /etc/hosts or DNS.

Step 1: Generate RSA Keys

Log in as the grid user (or oracle user, depending on which software you are configuring). You must repeat these steps for both users.

On both nodes, run the following command. When prompted for a passphrase, leave it empty by pressing Enter.

mkdir -p ~/.ssh
chmod 700 ~/.ssh
ssh-keygen -t rsa

This generates two files in ~/.ssh/:

1. id_rsa (Private Key)

2. id_rsa.pub (Public Key)

Step 2: Create the Authorized Keys File

The goal is to consolidate the public keys from all nodes into a single file called authorized_keys.

On Node 1:

Copy the public key of Node 1 into a new authorized_keys file:

cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys

On Node 2:

Send Node 2’s public key to Node 1:

scp ~/.ssh/id_rsa.pub grid@racnode1:~/.ssh/id_rsa_node2.pub

Back on Node 1:

Append Node 2’s key to the authorized list and send the complete file back to Node 2:

cat ~/.ssh/id_rsa_node2.pub >> ~/.ssh/authorized_keys
scp ~/.ssh/authorized_keys grid@racnode2:~/.ssh/

Step 3: Set Permissions

SSH is very strict about file permissions. If the permissions are too “open,” SSH will ignore the keys for security reasons. Run these on all nodes:

chmod 600 ~/.ssh/authorized_keys

Step 4: Establish First-Time Connectivity

You must manually SSH into every node (including the node itself) at least once to add the host signatures to the known_hosts file.

On Node 1, run:

ssh racnode1 date
ssh racnode1-priv date
ssh racnode2 date
ssh racnode2-priv date

On Node 2, run:

ssh racnode1 date
ssh racnode1-priv date
ssh racnode2 date
ssh racnode2-priv date

Note: If you are prompted “Are you sure you want to continue connecting (yes/no)?”, type yes. After this, the date command should return the system time without asking for a password.

Step 5: Verification (The Easy Way)

Oracle provides a utility called cluvfy (Cluster Verification Utility) bundled with the installation media. This is the gold standard for checking your work.

Navigate to your Grid installation media directory and run:

./runcluvfy.sh comp nodecon -n racnode1,racnode2 -verbose

If the check for “User equivalence” passes, your passwordless SSH is correctly configured.

Key Troubleshooting Tips

• Permissions: Ensure the home directory is not writable by “group” or “others” (chmod 700 ~).

• SELinux: Sometimes SELinux can block SSH key access. If you face issues, check /var/log/audit/audit.log.

• StrictModes: In /etc/ssh/sshd_config, if StrictModes is set to yes, ensure file ownership is correct.

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