Returns interfaces data.

def interfaces_info():
    """Returns interfaces data.
    """
    def replace(value):
        if value == netifaces.AF_LINK:
            return 'link'
        if value == netifaces.AF_INET:
            return 'ipv4'
        if value == netifaces.AF_INET6:
            return 'ipv6'
        return value

    results = {}
    for iface in netifaces.interfaces():
        addrs = netifaces.ifaddresses(iface)
        results[iface] = {replace(k): v for k, v in addrs.items()}

    return results