Retrieve the list of configured forwarded IP addresses.

    Args:
      interface: string, the output device to query.
      interface_ip: string, current interface ip address.

    Returns:
      list, the IP address strings.

def GetForwardedIps(self, interface, interface_ip=None):
    """Retrieve the list of configured forwarded IP addresses.

    Args:
      interface: string, the output device to query.
      interface_ip: string, current interface ip address.

    Returns:
      list, the IP address strings.
    """
    try:
      ips = netifaces.ifaddresses(interface)
      ips = ips[netifaces.AF_INET]
    except (ValueError, IndexError):
      return []
    forwarded_ips = []
    for ip in ips:
      if ip['addr'] != interface_ip:
        full_addr = '%s/%d' % (ip['addr'], netaddr.IPAddress(ip['netmask']).netmask_bits())
        forwarded_ips.append(full_addr)
    return self.ParseForwardedIps(forwarded_ips)