diff --git a/include/fileutils.h b/include/fileutils.h
index f3bdb5c..434eac0 100644
--- a/include/fileutils.h
+++ b/include/fileutils.h
@@ -23,6 +23,7 @@
 #include <cstdio>
 #include <ios>
 #include <filesystem>
+#include <map>
 
 #ifndef _WIN32
 #include <sys/stat.h>               // mode_t
@@ -91,5 +92,21 @@
  */
 int accessFile(const std::string& file, int mode);
 
+
+class IdList
+{
+public:
+    IdList() = default;
+    IdList(std::filesystem::path p): path(std::move(p)) {
+        load();
+    }
+    bool add(uint64_t id);
+private:
+    void load();
+    std::filesystem::path path;
+    std::map<uint64_t, std::chrono::system_clock::time_point> ids;
+    std::chrono::system_clock::time_point last_maintain;
+};
+
 } // namespace fileutils
 } // namespace dhtnet