def join_ssh(seed_host):
    """
    SSH configuration for joining node.
    """
    if not seed_host:
        error("No existing IP/hostname specified (use -c option)")

    utils.start_service("sshd.service", enable=True)
    configure_local_ssh_key()
    swap_public_ssh_key(seed_host)

    # This makes sure the seed host has its own SSH keys in its own
    # authorized_keys file (again, to help with the case where the
    # user has done manual initial setup without the assistance of
    # ha-cluster-init).
    rc, _, err = invoke("ssh root@{} crm cluster init -i {} ssh_remote".format(seed_host, _context.default_nic_list[0]))
    if not rc:
        error("Can't invoke crm cluster init -i {} ssh_remote on {}: {}".format(_context.default_nic_list[0], seed_host, err))