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Oh Chin Boon
Asked: 2013-03-25 23:17:58 +0800 CST

How do I SSH into a Linux server from a Linux bastion host?

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The scenario is like this: 

Windows workstation -> Linux bastion host -> Linux server

From my Windows workstation I use PuTTY to SSH into the Linux bastion host from which I then SSH into the Linux server.

Question is, how do I do that when the authentication between the bastion host and Linux server is ppk authentication and I do not wish to store the ppk key for the Linux server on my bastion host?

ssh

1 Answers

  1. This is usually approached by means of Using agent forwarding:

    Agent forwarding is a mechanism that allows applications on your SSH server machine to talk to the agent on your client machine.

    That is, assuming you are Using Pageant for authentication in the first place, you simply need to set the option to ‘Allow agent forwarding’ when starting your SSH session and you should be good to go, i.e. using ssh on the bastion host will automatically attempt to retrieve a key from your local Pageant process.

    • Obviously there are a few environmental constraints, most notably that at present, agent forwarding in SSH-2 is only available when your SSH server is OpenSSH, but accordingly I haven't had any problems using it with most regular Amazon EC2 AMIs, e.g. the official Ubuntu ones.
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