You are prompted to give the passphrase for the key.
To give passphrases for all keys, run the following command:
> ssh-socks-proxy-ctl key-passphrase --all
You are prompted to give passphrases for each key found by the SOCKS Proxy in turn.
After the passphrase has been given, it will be stored in cache and the key can be used non-interactively.
Note: The passphrase cache is used only for transparent tunneling with ssh-socks-proxy. Use ssh-add2 and ssh-agent2 to cache passphrases for ssh2, scp2, and sftp2. See the ssh-add2 and ssh-agent2 man pages for more information (Appendices ssh-add2 and ssh-agent2).