How to configure paswordless ssh with ssh-agent

1. Obtain your private ssh key (key format doesn’t matter)
   Let’s assume we have a key “key.pem”

2. Copy pubkey to the proxy server and the target one
   for i in 1 2; do ssh-copy-id ubuntu@10.10.10.1$i; done

3. Start locally ssh-agent, export connection details in shell
   eval${ssh-agent -s}

4. Add key to your current ssh session
   ssh-add -k key.pem; ssh-add -l

5. SSH to the Proxy (you don’t need to specify key, after step 4), configure forwarding if necessary
   ssh ubuntu@proxy
   vim /etc/ssh/ssh_config
   Host $host_ip ForwardAgent yes
6. Voila! Now you can ssh to Proxy server + 1 another server (A) + 1 (B).
   If you only want to passthrough 1 proxy server you don’t need to configure ForwardAgent option