Using Xagent, the SSH client on a remote host can use a user key used by Xshell, which is a user key held by Xagent. To use an Xagent user key on a remote host, both Xshell and the remote host SSH server must support agent-forwarding.
To Activate Agent-Forwarding on the ssh.com Server:

Open the /etc/ssh2/sshd2_config file.
Set value for AllowAgentForwarding option as follows: AllowAgentForwardingyes
Restart SSH server.

Note
OpenSSH servers automatically enable the agent forwarding feature unless user specifies the no-agent-forwarding option.

To Use Xagent Key on the Remote Host:

Set Xshell to use Xagent.
Execute Xagent if Xagent is not running.
Connect to SSH server and login.
- Note
  If the SSH server supports the agent forwarding feature, the environment variable for agent forwarding (SSH_AUTH_SOCK or SSH2_AUTH_SOCK) is set to a proper value.
Connect to another server, which supports public key authentication, from the remote server.
When Passphrase dialog box is displayed, enter passphrase to the selected user key.

Note
Passphrase dialog box is displayed only when the selected key status is Close. You can check user key status in Xagent user keys list.