Establishing a passwordless SSH connection between two Linux servers is a common practice to streamline secure remote access. This tutorial will guide you through the steps to set up passwordless SSH authentication and offer troubleshooting tips if the connection doesn’t work as expected.
Two Linux servers (Server A and Server B)
Administrative access to both servers
Log in to Server A using SSH or physical access.
Open a terminal window.
Generate an SSH key pair by running the following command:
ssh-keygen -t rsa
You can press Enter to accept the default location for the key pair (~/.ssh/id_rsa) and leave the passphrase empty for passwordless authentication.
4. Confirm the key generation by pressing Enter.
5. This will create a private key (id_rsa) and a public key (id_rsa.pub) in the ~/.ssh/ directory.
Use the ssh-copy-id command to copy the public key to Server B:
ssh-copy-id user@serverB_IP
Replace user with your username on Server B, and serverB_IP with the IP address or hostname of Server B.
You will be prompted to enter the password for your user account on Server B.
After successfully copying the public key, you should see a message confirming the key was added.
Attempt to SSH into Server B from Server A:
ssh user@serverB_IP
You should now be able to access Server B without being prompted for a password.
If the passwordless connection doesn’t work, here are some troubleshooting steps:
Check Permissions: Ensure the .ssh directory on both Server A and Server B has the correct permissions. It should be owned by the user and have restricted permissions:
chmod 700 ~/.ssh chmod 600 ~/.ssh/authorized_keys
Key File Names: Verify that you are using the default key names (id_rsa and id_rsa.pub) or the names you specified during key generation.
SSH Agent: Make sure you have added the private key to the SSH agent on Server A using ssh-add:
ssh-add ~/.ssh/id_rsa
3. Firewall and SELinux: Check if the firewall on either server is blocking SSH access and ensure SELinux permissions are not causing issues.
4. Logs: Check the SSH server logs on Server B for any error messages:
tail -f /var/log/auth.log # On Ubuntu/Debian tail -f /var/log/secure # On CentOS/RHEL
5. Debugging Mode: You can run SSH in debugging mode to get more information:
ssh -v user@serverB_IP
This will provide detailed debug output, which can help pinpoint the issue.
By following these steps and considering the troubleshooting tips, you should be able to establish a passwordless SSH connection between your Linux servers for secure and convenient remote access.
From another host, use SSH to log in into the host that you are testing as the SSH user. $ ssh -l user-name host-name user-name. The user name for the SSH user's account on the host. ...
In response to the prompt, type your password. If this step succeeds, your setup of SSH is complete.
SSH passwordless login is an SSH authentication method that employs a pair of public and private keys for asymmetric encryption. The public key resides on the server, and only a client that presents the private key can connect.
Another command you can use to check connectivity is traceroute . Again this tool will not show connectivity through one server to another (same issue as ping), but it will show you the path through the network that your taking to get to another server. ssh can be used in BatchMode to test connectivity.
To list all connected SSH sessions, you can use the “ss -t -a” command. The “-t” option shows only TCP connections and the “-a” option shows all sockets. The grep command is used to filter the output and shows only ssh connections.
For Linux. Open a terminal and enter the following command: ssh @ . For example, if the IP address is 192.168. 99.118 and the username is "rancher", enter the command ssh rancher@192.168.99.118 .
SSH or Secure Shell is a network communication protocol that enables two computers to communicate (c.f http or hypertext transfer protocol, which is the protocol used to transfer hypertext such as web pages) and share data.
The ssh command provides a secure encrypted connection between two hosts over an insecure network. This connection can also be used for terminal access, file transfers, and for tunneling other applications. Graphical X11 applications can also be run securely over SSH from a remote location.
To create a trust relationship, use the ssh-keygen program to generate the private and public key pair. The private key stays on the host with the agent. Copy the public key to the target remote host that has no agent. is the user name on the SSH user account you created on the target computer.
Address: Suite 751 871 Lissette Throughway, West Kittie, NH 41603
Phone: +2366831109631
Job: Sales Producer
Hobby: Creative writing, Motor sports, Do it yourself, Skateboarding, Coffee roasting, Calligraphy, Stand-up comedy
Introduction: My name is Laurine Ryan, I am a adorable, fair, graceful, spotless, gorgeous, homely, cooperative person who loves writing and wants to share my knowledge and understanding with you.
We notice you're using an ad blocker
Without advertising income, we can't keep making this site awesome for you.
