public static boolean WritePrefix(String hostname, String prefix)
    {
        Prefixes.add(hostname + " " + prefix);
        try
        {
            BufferedWriter writer = new BufferedWriter(new FileWriter(PrefixesFile, true));
            writer.write(hostname + " " + prefix + "\r\n");
            writer.close();
            return true;
        }
        catch(Exception e)
        {
            Utils.LogException(e, "writing prefix");
            return false;
        }
    }