I'd be needing to connect to several AWS EC2 instances and putty works fine with the keys, but it's just one at a time. I also tried Remmina, however it keeps asking SSH private keyphrase what it shouldn't. Any other suggestion?
62 Answers
I use ssh-agent to load keys. You can control the length of time the keys are active.
You can also use a private configuration file to specify the key and other settings for individual hosts.
If I understand your question correctly you want to manage multiple simultaneous SSH connections and their associated shell sessions. For that job use the default SSH client ssh and your favourite terminal emulator/multiplexer (see What terminal emulators are available for heavy terminal users? for suggestions).
If you want to avoid retyping the SSH key pass phrase for every new connection you should use a "key agent" like ssh-agent to keep a copy of once unlocked SSH keys in memory for later reuse.