diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 1cb942f..92c7b18 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -1,5 +1,5 @@
 set(SOURCE stellar_config.cpp stellar_stat.cpp stellar_core.cpp)
-set(LIBRARY session_manager plugin_manager ip_reassembly packet_io packet pthread fieldstat4 toml nmx_pool)
+set(LIBRARY session_manager plugin_manager ip_reassembly packet_io snowflake packet pthread fieldstat4 toml nmx_pool)
 
 set(PLUGIN http glimpse_detector)
 
diff --git a/src/core/stellar_config.h b/src/core/stellar_config.h
index d4d622e..d1d5500 100644
--- a/src/core/stellar_config.h
+++ b/src/core/stellar_config.h
@@ -6,7 +6,6 @@ extern "C"
 #endif
 
 #include "packet_io.h"
-#include "snowflake.h"
 #include "ip_reassembly.h"
 #include "session_manager.h"
 
@@ -26,6 +25,12 @@ struct schedule_options
     uint64_t packet_io_yield_interval; // range: [1, 60000] (ms)
 };
 
+struct snowflake_options
+{
+    uint8_t snowflake_base;
+    uint8_t snowflake_offset;
+};
+
 struct stellar_config
 {
     struct packet_io_options pkt_io_opts;
diff --git a/src/core/stellar_core.cpp b/src/core/stellar_core.cpp
index baac4e1..7f83d7d 100644
--- a/src/core/stellar_core.cpp
+++ b/src/core/stellar_core.cpp
@@ -59,6 +59,7 @@ struct stellar_thread
     uint16_t idx;
     uint64_t is_runing;
     struct schedule_data sched_data;
+    struct snowflake *snowflake;
     struct ip_reassembly *ip_mgr;
     struct session_manager *sess_mgr;
     struct stellar *st;
@@ -84,7 +85,10 @@ struct stellar
     struct stellar_config config;
 };
 
-static thread_local uint16_t __thread_id = 0; // TODO
+static thread_local uint16_t __current_thread_idx = UINT16_MAX;
+static thread_local struct snowflake *__current_thread_snowflake = NULL;
+
+uint64_t stellar_generate_session_id(uint64_t now_sec);
 
 /******************************************************************************
  * Stellar Thread Main Loop
@@ -191,7 +195,9 @@ static void *work_thread(void *arg)
     struct packet_io *packet_io = runtime->packet_io;
     struct plugin_manager_schema *plug_mgr = runtime->plug_mgr;
     uint16_t thr_idx = thread->idx;
-    __thread_id = thr_idx;
+
+    __current_thread_idx = thr_idx;
+    __current_thread_snowflake = thread->snowflake;
 
     memset(packets, 0, sizeof(packets));
 
@@ -407,12 +413,19 @@ static int stellar_thread_init(struct stellar *st)
         thread->sched_data.merge_stat_interval = config->sched_opts.merge_stat_interval;
         thread->sched_data.packet_io_yield_interval = config->sched_opts.packet_io_yield_interval;
 
+        thread->snowflake = snowflake_new(i, config->snowflake_opts.snowflake_base, config->snowflake_opts.snowflake_offset);
+        if (thread->snowflake == NULL)
+        {
+            STELLAR_LOG_ERROR("unable to create snowflake id generator");
+            return -1;
+        }
         thread->sess_mgr = session_manager_new(&config->sess_mgr_opts, now_ms);
         if (thread->sess_mgr == NULL)
         {
             STELLAR_LOG_ERROR("unable to create session manager");
             return -1;
         }
+        session_manager_set_session_id_generator(thread->sess_mgr, stellar_generate_session_id);
         thread->ip_mgr = ip_reassembly_new(&config->ip_reass_opts);
         if (thread->ip_mgr == NULL)
         {
@@ -436,8 +449,9 @@ static void stellar_thread_clean(struct stellar *st)
         struct stellar_thread *thread = &runtime->threads[i];
         if (ATOMIC_READ(&thread->is_runing) == 0)
         {
-            session_manager_free(thread->sess_mgr);
             ip_reassembly_free(thread->ip_mgr);
+            session_manager_free(thread->sess_mgr);
+            snowflake_free(thread->snowflake);
         }
     }
     STELLAR_LOG_FATAL("worker thread context cleaned");
@@ -526,12 +540,6 @@ struct stellar *stellar_new(const char *stellar_cfg_file, const char *plugin_cfg
     }
     stellar_config_print(config);
 
-    if (snowflake_id_init(&config->snowflake_opts) != 0)
-    {
-        STELLAR_LOG_ERROR("unable to init id generator");
-        goto error_out;
-    }
-
     runtime->stat = stellar_stat_new(config->pkt_io_opts.nr_threads);
     if (runtime->stat == NULL)
     {
@@ -666,7 +674,30 @@ struct session_manager *stellar_get_session_manager(const struct stellar *st)
 
 uint16_t stellar_get_current_thread_index()
 {
-    return __thread_id;
+    if (__current_thread_idx == UINT16_MAX)
+    {
+        printf("get current thread index before set\n");
+        abort();
+        return UINT16_MAX;
+    }
+    else
+    {
+        return __current_thread_idx;
+    }
+}
+
+uint64_t stellar_generate_session_id(uint64_t now_sec)
+{
+    if (__current_thread_snowflake == NULL)
+    {
+        printf("get current thread snowflake before set\n");
+        abort();
+        return 0;
+    }
+    else
+    {
+        return snowflake_generate(__current_thread_snowflake, now_sec);
+    }
 }
 
 // only send user crafted packet, can't send packet which come from network
diff --git a/src/session/CMakeLists.txt b/src/session/CMakeLists.txt
index 3f0f5db..e632679 100644
--- a/src/session/CMakeLists.txt
+++ b/src/session/CMakeLists.txt
@@ -8,9 +8,9 @@ add_library(session_manager
     session_transition.cpp
 )
 target_include_directories(session_manager PUBLIC ${CMAKE_CURRENT_LIST_DIR})
-target_include_directories(session_manager PUBLIC ${CMAKE_SOURCE_DIR}/src/stellar)
+target_include_directories(session_manager PUBLIC ${CMAKE_SOURCE_DIR}/src/core)
 target_include_directories(session_manager PUBLIC ${CMAKE_SOURCE_DIR}/include)
 target_include_directories(session_manager PUBLIC ${CMAKE_SOURCE_DIR}/src/utils)
-target_link_libraries(session_manager timeout snowflake packet dablooms log tcp_reassembly)
+target_link_libraries(session_manager timeout packet tcp_reassembly)
 
 add_subdirectory(test)
\ No newline at end of file
diff --git a/src/session/session_manager.cpp b/src/session/session_manager.cpp
index 4fb4e86..a9cb5e1 100644
--- a/src/session/session_manager.cpp
+++ b/src/session/session_manager.cpp
@@ -6,7 +6,6 @@
 #include "utils.h"
 #include "packet_helper.h"
 #include "packet_filter.h"
-#include "snowflake.h"
 #include "session_private.h"
 #include "session_pool.h"
 #include "session_table.h"
@@ -37,6 +36,7 @@ struct session_manager
       * because the function is called by pluin and has no time input.
       */
      uint64_t now_ms;
+     session_id_generate_fn id_generator;
 };
 
 #define EVICTE_SESSION_BURST (RX_BURST_MAX)
@@ -535,7 +535,15 @@ static void session_update(struct session_manager *mgr, struct session *sess, en
 {
      if (session_get_current_state(sess) == SESSION_STATE_INIT)
      {
-          session_set_id(sess, snowflake_id_generate(mgr->now_ms / 1000));
+          if (mgr->id_generator)
+          {
+               uint64_t sess_id = mgr->id_generator(mgr->now_ms / 1000);
+               session_set_id(sess, sess_id);
+          }
+          else
+          {
+               session_set_id(sess, 0);
+          }
           enum packet_direction pkt_dir = packet_get_direction(pkt);
           if (dir == FLOW_DIRECTION_C2S)
           {
@@ -974,6 +982,11 @@ void session_manager_free(struct session_manager *mgr)
      }
 }
 
+void session_manager_set_session_id_generator(struct session_manager *mgr, session_id_generate_fn generator)
+{
+     mgr->id_generator = generator;
+}
+
 void session_manager_record_duplicated_packet(struct session_manager *mgr, const struct packet *pkt)
 {
      if (mgr->opts.duplicated_packet_filter_enable)
diff --git a/src/session/session_manager.h b/src/session/session_manager.h
index 4e1d2be..a7ede4b 100644
--- a/src/session/session_manager.h
+++ b/src/session/session_manager.h
@@ -132,6 +132,9 @@ struct session_scan_opts
 struct session_manager;
 struct session_manager *session_manager_new(struct session_manager_options *opts, uint64_t now_ms);
 void session_manager_free(struct session_manager *mgr);
+
+typedef uint64_t (*session_id_generate_fn)(uint64_t now_ms);
+void session_manager_set_session_id_generator(struct session_manager *mgr, session_id_generate_fn generator);
 void session_manager_record_duplicated_packet(struct session_manager *mgr, const struct packet *pkt);
 
 struct session *session_manager_new_session(struct session_manager *mgr, const struct packet *pkt, uint64_t now_ms);
diff --git a/src/session/test/gtest_case_tcp_fast_open.cpp b/src/session/test/gtest_case_tcp_fast_open.cpp
index 4216655..3680faa 100644
--- a/src/session/test/gtest_case_tcp_fast_open.cpp
+++ b/src/session/test/gtest_case_tcp_fast_open.cpp
@@ -3,10 +3,8 @@
 #include "tuple.h"
 #include "packet_private.h"
 #include "packet_parser.h"
-#include "snowflake.h"
 #include "session_private.h"
 #include "session_manager.h"
-#include "tcp_reassembly.h"
 
 struct session_manager_options opts = {
     // max session number
@@ -48,6 +46,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 /******************************************************************************
  * case: TCP init -> opening (by TCP Fast Open)
  ******************************************************************************/
@@ -310,6 +314,7 @@ TEST(CASE, TCP_FAST_OPEN)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S fast open packet\n");
@@ -420,11 +425,6 @@ TEST(CASE, TCP_FAST_OPEN)
 
 int main(int argc, char **argv)
 {
-    struct snowflake_options opt = {
-        .snowflake_base = 1,
-        .snowflake_offset = 2,
-    };
-    snowflake_id_init(&opt);
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
-}
+}
\ No newline at end of file
diff --git a/src/session/test/gtest_filter_tcp_dupkt.cpp b/src/session/test/gtest_filter_tcp_dupkt.cpp
index 1b5a8bd..93c3243 100644
--- a/src/session/test/gtest_filter_tcp_dupkt.cpp
+++ b/src/session/test/gtest_filter_tcp_dupkt.cpp
@@ -1,6 +1,5 @@
 #include <gtest/gtest.h>
 
-#include "packet_helper.h"
 #include "packet_private.h"
 #include "packet_parser.h"
 #include "session_private.h"
@@ -47,12 +46,18 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 static void packet_set_ip_id(struct packet *pkt, uint16_t ip_id)
 {
     const struct layer_private *ipv4_layer = packet_get_innermost_layer(pkt, LAYER_PROTO_IPV4);
     EXPECT_TRUE(ipv4_layer);
     struct ip *hdr = (struct ip *)ipv4_layer->hdr_ptr;
-    ip4_hdr_set_ipid(hdr, ip_id);
+    hdr->ip_id = htons(ip_id);
 }
 
 #if 1
@@ -65,6 +70,7 @@ TEST(TCP_DUPKT_FILTER_ENABLE, SYN_DUP)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -131,6 +137,7 @@ TEST(TCP_DUPKT_FILTER_ENABLE, SYNACK_DUP)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // S2C SYNACK Packet
     printf("\n=> Packet Parse: TCP S2C SYNACK packet\n");
@@ -198,6 +205,7 @@ TEST(TCP_DUPKT_FILTER_ENABLE, SKIP)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -284,6 +292,7 @@ TEST(TCP_DUPKT_FILTER_DISABLE, SYN_DUP)
 
     mgr = session_manager_new(&_opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -334,6 +343,7 @@ TEST(TCP_DUPKT_FILTER_DISABLE, SYNACK_DUP)
 
     mgr = session_manager_new(&_opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // S2C SYNACK Packet
     printf("\n=> Packet Parse: TCP S2C SYNACK packet\n");
@@ -375,4 +385,4 @@ int main(int argc, char **argv)
 {
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
-}
+}
\ No newline at end of file
diff --git a/src/session/test/gtest_overload_evict_tcp_sess.cpp b/src/session/test/gtest_overload_evict_tcp_sess.cpp
index 632df10..a50d858 100644
--- a/src/session/test/gtest_overload_evict_tcp_sess.cpp
+++ b/src/session/test/gtest_overload_evict_tcp_sess.cpp
@@ -1,7 +1,6 @@
 #include <gtest/gtest.h>
 
 #include "utils.h"
-#include "packet_helper.h"
 #include "packet_private.h"
 #include "packet_parser.h"
 #include "session_private.h"
@@ -48,12 +47,18 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 static void packet_set_ip_src_addr(struct packet *pkt, uint32_t addr)
 {
     const struct layer_private *ipv4_layer = packet_get_innermost_layer(pkt, LAYER_PROTO_IPV4);
     EXPECT_TRUE(ipv4_layer);
     struct ip *hdr = (struct ip *)ipv4_layer->hdr_ptr;
-    ip4_hdr_set_src_addr(hdr, addr);
+    hdr->ip_src.s_addr = htonl(addr);
 }
 
 #if 1
@@ -65,6 +70,7 @@ TEST(TCP_OVERLOAD, EVICT_OLD_SESS)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -106,6 +112,7 @@ TEST(TCP_OVERLOAD, EVICT_NEW_SESS)
 
     mgr = session_manager_new(&_opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
diff --git a/src/session/test/gtest_overload_evict_udp_sess.cpp b/src/session/test/gtest_overload_evict_udp_sess.cpp
index bdbd1bb..7137896 100644
--- a/src/session/test/gtest_overload_evict_udp_sess.cpp
+++ b/src/session/test/gtest_overload_evict_udp_sess.cpp
@@ -1,7 +1,6 @@
 #include <gtest/gtest.h>
 
 #include "utils.h"
-#include "packet_helper.h"
 #include "packet_private.h"
 #include "packet_parser.h"
 #include "session_private.h"
@@ -48,12 +47,18 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 static void packet_set_ip_src_addr(struct packet *pkt, uint32_t addr)
 {
     const struct layer_private *ipv4_layer = packet_get_innermost_layer(pkt, LAYER_PROTO_IPV4);
     EXPECT_TRUE(ipv4_layer);
     struct ip *hdr = (struct ip *)ipv4_layer->hdr_ptr;
-    ip4_hdr_set_src_addr(hdr, addr);
+    hdr->ip_src.s_addr = htonl(addr);
 }
 
 #if 1
@@ -66,6 +71,7 @@ TEST(UDP_OVERLOAD, EVICT_OLD_SESS)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S REQ Packet
     printf("\n=> Packet Parse: UDP C2S REQ packet\n");
@@ -155,6 +161,7 @@ TEST(UDP_OVERLOAD, EVICT_NEW_SESS)
 
     mgr = session_manager_new(&_opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S REQ Packet
     printf("\n=> Packet Parse: UDP C2S REQ packet\n");
diff --git a/src/session/test/gtest_sess_mgr_scan.cpp b/src/session/test/gtest_sess_mgr_scan.cpp
index a8984af..708554c 100644
--- a/src/session/test/gtest_sess_mgr_scan.cpp
+++ b/src/session/test/gtest_sess_mgr_scan.cpp
@@ -1,6 +1,5 @@
 #include <gtest/gtest.h>
 
-#include "snowflake.h"
 #include "session_private.h"
 #include "session_manager.h"
 #include "packet_private.h"
@@ -47,6 +46,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 static inline void packet_overwrite_src_addr(struct packet *pkt, struct in_addr addr)
 {
     const struct layer_private *ipv4_layer = packet_get_innermost_layer(pkt, LAYER_PROTO_IPV4);
@@ -128,6 +133,7 @@ TEST(SESS_MGR_SCAN, OPTS)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // new session
     memset(&pkt, 0, sizeof(pkt));
@@ -388,11 +394,6 @@ TEST(SESS_MGR_SCAN, OPTS)
 
 int main(int argc, char **argv)
 {
-    struct snowflake_options opt = {
-        .snowflake_base = 1,
-        .snowflake_offset = 2,
-    };
-    snowflake_id_init(&opt);
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
 }
\ No newline at end of file
diff --git a/src/session/test/gtest_sess_mgr_tcp_reassembly.cpp b/src/session/test/gtest_sess_mgr_tcp_reassembly.cpp
index f92a6db..9e5d0da 100644
--- a/src/session/test/gtest_sess_mgr_tcp_reassembly.cpp
+++ b/src/session/test/gtest_sess_mgr_tcp_reassembly.cpp
@@ -1,11 +1,9 @@
 #include <gtest/gtest.h>
 
-#include "packet_helper.h"
 #include "packet_private.h"
 #include "packet_parser.h"
 #include "session_private.h"
 #include "session_manager.h"
-#include "tcp_reassembly.h"
 #include "test_packets.h"
 
 struct session_manager_options opts = {
@@ -48,6 +46,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 static void hex_dump(const char *payload, uint32_t len)
 {
     printf("Payload Length: %u\n", len);
@@ -72,6 +76,7 @@ TEST(SESS_MGR_TCP_REASSEMBLY, OUT_OF_ORDER)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -263,6 +268,7 @@ TEST(SESS_MGR_TCP_REASSEMBLY, SEQ_WRAPAROUND)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -350,4 +356,4 @@ int main(int argc, char **argv)
 {
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
-}
+}
\ No newline at end of file
diff --git a/src/session/test/gtest_state_tcp_active_to_closing.cpp b/src/session/test/gtest_state_tcp_active_to_closing.cpp
index 219d6a5..5f79726 100644
--- a/src/session/test/gtest_state_tcp_active_to_closing.cpp
+++ b/src/session/test/gtest_state_tcp_active_to_closing.cpp
@@ -2,10 +2,8 @@
 #include <gtest/gtest.h>
 
 #include "tuple.h"
-#include "packet_helper.h"
 #include "packet_private.h"
 #include "packet_parser.h"
-#include "snowflake.h"
 #include "session_private.h"
 #include "session_manager.h"
 #include "test_packets.h"
@@ -50,6 +48,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 static void build_active_tcp_session(struct session_manager *mgr, struct session *sess)
 {
     struct packet pkt;
@@ -94,6 +98,7 @@ TEST(TCP_ACTIVE_TO_CLOSING, BY_FIN_FIN)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet & C2S DATA Packet
     build_active_tcp_session(mgr, sess);
@@ -185,6 +190,7 @@ TEST(TCP_ACTIVE_TO_CLOSING, BY_C2S_RST)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet & C2S DATA Packet
     build_active_tcp_session(mgr, sess);
@@ -198,8 +204,7 @@ TEST(TCP_ACTIVE_TO_CLOSING, BY_C2S_RST)
     const struct layer_private *tcp_layer = packet_get_innermost_layer(&pkt, LAYER_PROTO_TCP);
     EXPECT_TRUE(tcp_layer);
     struct tcphdr *hdr = (struct tcphdr *)tcp_layer->hdr_ptr;
-    tcp_hdr_set_flags(hdr, 0);
-    tcp_hdr_set_rst_flag(hdr, true);
+    hdr->th_flags = TH_RST;
     printf("<= Packet Parse: done\n\n");
 
     // lookup session
@@ -271,6 +276,7 @@ TEST(TCP_ACTIVE_TO_CLOSING, BY_S2C_RST)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet & C2S DATA Packet
     build_active_tcp_session(mgr, sess);
@@ -284,8 +290,7 @@ TEST(TCP_ACTIVE_TO_CLOSING, BY_S2C_RST)
     const struct layer_private *tcp_layer = packet_get_innermost_layer(&pkt, LAYER_PROTO_TCP);
     EXPECT_TRUE(tcp_layer);
     struct tcphdr *hdr = (struct tcphdr *)tcp_layer->hdr_ptr;
-    tcp_hdr_set_flags(hdr, 0);
-    tcp_hdr_set_rst_flag(hdr, true);
+    hdr->th_flags = TH_RST;
     printf("<= Packet Parse: done\n\n");
 
     // lookup session
@@ -355,6 +360,7 @@ TEST(TCP_ACTIVE_TO_CLOSING, BY_DATA_TIMEOUT)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet & C2S DATA Packet
     build_active_tcp_session(mgr, sess);
@@ -404,6 +410,7 @@ TEST(TCP_ACTIVE_TO_CLOSING, BY_C2S_HALF_CLOSED_TIMEOUT)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet & C2S DATA Packet
     build_active_tcp_session(mgr, sess);
@@ -483,6 +490,7 @@ TEST(TCP_ACTIVE_TO_CLOSING, BY_S2C_HALF_CLOSED_TIMEOUT)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet & C2S DATA Packet
     build_active_tcp_session(mgr, sess);
@@ -549,11 +557,6 @@ TEST(TCP_ACTIVE_TO_CLOSING, BY_S2C_HALF_CLOSED_TIMEOUT)
 
 int main(int argc, char **argv)
 {
-    struct snowflake_options opt = {
-        .snowflake_base = 1,
-        .snowflake_offset = 2,
-    };
-    snowflake_id_init(&opt);
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
-}
+}
\ No newline at end of file
diff --git a/src/session/test/gtest_state_tcp_init_to_opening.cpp b/src/session/test/gtest_state_tcp_init_to_opening.cpp
index 26fb4ca..30c07fc 100644
--- a/src/session/test/gtest_state_tcp_init_to_opening.cpp
+++ b/src/session/test/gtest_state_tcp_init_to_opening.cpp
@@ -2,10 +2,8 @@
 #include <gtest/gtest.h>
 
 #include "tuple.h"
-#include "packet_helper.h"
 #include "packet_private.h"
 #include "packet_parser.h"
-#include "snowflake.h"
 #include "session_private.h"
 #include "session_manager.h"
 #include "test_packets.h"
@@ -50,6 +48,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 /******************************************************************************
  * case: TCP init -> opening (by SYN)
  ******************************************************************************/
@@ -65,6 +69,7 @@ TEST(TCP_INIT_TO_OPENING, BY_SYN)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -142,6 +147,7 @@ TEST(TCP_INIT_TO_OPENING, BY_SYNACK)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // S2C SYNACK Packet
     printf("\n=> Packet Parse: TCP S2C SYNACK packet\n");
@@ -219,6 +225,7 @@ TEST(TCP_INIT_TO_OPENING, BY_SYN_SYNACK)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -308,6 +315,7 @@ TEST(TCP_INIT_TO_OPENING, BY_SYN_SYNACK_ACK)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -411,6 +419,7 @@ TEST(TCP_INIT_TO_OPENING, BY_SYN_RETRANSMISSION)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -432,7 +441,7 @@ TEST(TCP_INIT_TO_OPENING, BY_SYN_RETRANSMISSION)
     packet_parse(&pkt, (const char *)syn_retransmission, sizeof(tcp_pkt1_c2s_syn));
     const struct layer_private *ipv4_layer = packet_get_innermost_layer(&pkt, LAYER_PROTO_IPV4);
     struct ip *hdr = (struct ip *)ipv4_layer->hdr_ptr;
-    ip4_hdr_set_ipid(hdr, 0x1234);
+    hdr->ip_id = htons(0x1234);
     printf("<= Packet Parse: done\n\n");
 
     // lookup session
@@ -507,6 +516,7 @@ TEST(TCP_INIT_TO_OPENING, BY_SYNACK_RETRANSMISSION)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // S2C SYNACK Packet
     printf("\n=> Packet Parse: TCP S2C SYNACK packet\n");
@@ -529,7 +539,7 @@ TEST(TCP_INIT_TO_OPENING, BY_SYNACK_RETRANSMISSION)
     const struct layer_private *ipv4_layer = packet_get_innermost_layer(&pkt, LAYER_PROTO_IPV4);
     EXPECT_TRUE(ipv4_layer);
     struct ip *hdr = (struct ip *)ipv4_layer->hdr_ptr;
-    ip4_hdr_set_ipid(hdr, 0x1234);
+    hdr->ip_id = htons(0x1234);
     printf("<= Packet Parse: done\n\n");
 
     // lookup session
@@ -602,6 +612,7 @@ TEST(TCP_INIT_TO_OPENING, BY_C2S_ASMMETRIC)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -691,6 +702,7 @@ TEST(TCP_INIT_TO_OPENING, BY_S2C_ASMMETRIC)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // S2C SYNACK Packet
     printf("\n=> Packet Parse: TCP S2C SYNACK packet\n");
@@ -767,11 +779,6 @@ TEST(TCP_INIT_TO_OPENING, BY_S2C_ASMMETRIC)
 
 int main(int argc, char **argv)
 {
-    struct snowflake_options opt = {
-        .snowflake_base = 1,
-        .snowflake_offset = 2,
-    };
-    snowflake_id_init(&opt);
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
-}
+}
\ No newline at end of file
diff --git a/src/session/test/gtest_state_tcp_init_to_opening_to_active_to_closing_to_closed.cpp b/src/session/test/gtest_state_tcp_init_to_opening_to_active_to_closing_to_closed.cpp
index 215cab9..98b4ea2 100644
--- a/src/session/test/gtest_state_tcp_init_to_opening_to_active_to_closing_to_closed.cpp
+++ b/src/session/test/gtest_state_tcp_init_to_opening_to_active_to_closing_to_closed.cpp
@@ -4,7 +4,6 @@
 #include "tuple.h"
 #include "packet_private.h"
 #include "packet_parser.h"
-#include "snowflake.h"
 #include "session_private.h"
 #include "session_manager.h"
 #include "test_packets.h"
@@ -49,6 +48,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 #if 1
 TEST(TCP_INIT_TO_OPENING_TO_ACTIVE_TO_CLOSING_TO_CLOSED, TEST)
 {
@@ -60,6 +65,7 @@ TEST(TCP_INIT_TO_OPENING_TO_ACTIVE_TO_CLOSING_TO_CLOSED, TEST)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -433,11 +439,6 @@ TEST(TCP_INIT_TO_OPENING_TO_ACTIVE_TO_CLOSING_TO_CLOSED, TEST)
 
 int main(int argc, char **argv)
 {
-    struct snowflake_options opt = {
-        .snowflake_base = 1,
-        .snowflake_offset = 2,
-    };
-    snowflake_id_init(&opt);
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
-}
+}
\ No newline at end of file
diff --git a/src/session/test/gtest_state_tcp_opening_to_active.cpp b/src/session/test/gtest_state_tcp_opening_to_active.cpp
index f49916a..d0fb0aa 100644
--- a/src/session/test/gtest_state_tcp_opening_to_active.cpp
+++ b/src/session/test/gtest_state_tcp_opening_to_active.cpp
@@ -4,7 +4,6 @@
 #include "tuple.h"
 #include "packet_private.h"
 #include "packet_parser.h"
-#include "snowflake.h"
 #include "session_private.h"
 #include "session_manager.h"
 #include "test_packets.h"
@@ -49,6 +48,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 /******************************************************************************
  * case: TCP opening -> active (by C2S DATA)
  ******************************************************************************/
@@ -64,6 +69,7 @@ TEST(TCP_OPENING_TO_ACTIVE, BY_SYN_C2S_DATA)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -153,6 +159,7 @@ TEST(TCP_OPENING_TO_ACTIVE, BY_SYNACK_S2C_DATA)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // S2C SYNACK Packet
     printf("\n=> Packet Parse: TCP S2C SYNACK packet\n");
@@ -229,11 +236,6 @@ TEST(TCP_OPENING_TO_ACTIVE, BY_SYNACK_S2C_DATA)
 
 int main(int argc, char **argv)
 {
-    struct snowflake_options opt = {
-        .snowflake_base = 1,
-        .snowflake_offset = 2,
-    };
-    snowflake_id_init(&opt);
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
-}
+}
\ No newline at end of file
diff --git a/src/session/test/gtest_state_tcp_opening_to_closing.cpp b/src/session/test/gtest_state_tcp_opening_to_closing.cpp
index 83d5f81..e53630f 100644
--- a/src/session/test/gtest_state_tcp_opening_to_closing.cpp
+++ b/src/session/test/gtest_state_tcp_opening_to_closing.cpp
@@ -2,10 +2,8 @@
 #include <gtest/gtest.h>
 
 #include "tuple.h"
-#include "packet_helper.h"
 #include "packet_private.h"
 #include "packet_parser.h"
-#include "snowflake.h"
 #include "session_private.h"
 #include "session_manager.h"
 #include "test_packets.h"
@@ -50,6 +48,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 /******************************************************************************
  * case: TCP opening -> closing (by FIN-FIN)
  ******************************************************************************/
@@ -65,6 +69,7 @@ TEST(TCP_OPENING_TO_CLOSING, BY_FIN_FIN)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -165,6 +170,7 @@ TEST(TCP_OPENING_TO_CLOSING, BY_C2S_RST)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -187,8 +193,7 @@ TEST(TCP_OPENING_TO_CLOSING, BY_C2S_RST)
     const struct layer_private *tcp_layer = packet_get_innermost_layer(&pkt, LAYER_PROTO_TCP);
     EXPECT_TRUE(tcp_layer);
     struct tcphdr *hdr = (struct tcphdr *)tcp_layer->hdr_ptr;
-    tcp_hdr_set_flags(hdr, 0);
-    tcp_hdr_set_rst_flag(hdr, true);
+    hdr->th_flags = TH_RST;
     printf("<= Packet Parse: done\n\n");
 
     // lookup session
@@ -260,6 +265,7 @@ TEST(TCP_OPENING_TO_CLOSING, BY_S2C_RST)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -282,8 +288,7 @@ TEST(TCP_OPENING_TO_CLOSING, BY_S2C_RST)
     const struct layer_private *tcp_layer = packet_get_innermost_layer(&pkt, LAYER_PROTO_TCP);
     EXPECT_TRUE(tcp_layer);
     struct tcphdr *hdr = (struct tcphdr *)tcp_layer->hdr_ptr;
-    tcp_hdr_set_flags(hdr, 0);
-    tcp_hdr_set_rst_flag(hdr, true);
+    hdr->th_flags = TH_RST;
     printf("<= Packet Parse: done\n\n");
 
     // lookup session
@@ -354,6 +359,7 @@ TEST(TCP_OPENING_TO_CLOSING, BY_INIT_TIMEOUT)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -412,6 +418,7 @@ TEST(TCP_OPENING_TO_CLOSING, BY_HANDSHAKE_TIMEOUT)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -501,6 +508,7 @@ TEST(TCP_OPENING_TO_CLOSING, BY_DATA_TIMEOUT)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -602,6 +610,7 @@ TEST(TCP_OPENING_TO_CLOSING, BY_C2S_HALF_FIN)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -690,6 +699,7 @@ TEST(TCP_OPENING_TO_CLOSING, BY_S2C_HALF_FIN)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
@@ -765,11 +775,6 @@ TEST(TCP_OPENING_TO_CLOSING, BY_S2C_HALF_FIN)
 
 int main(int argc, char **argv)
 {
-    struct snowflake_options opt = {
-        .snowflake_base = 1,
-        .snowflake_offset = 2,
-    };
-    snowflake_id_init(&opt);
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
-}
+}
\ No newline at end of file
diff --git a/src/session/test/gtest_state_udp_init_to_opening_to_active_to_closing.cpp b/src/session/test/gtest_state_udp_init_to_opening_to_active_to_closing.cpp
index bc0ec50..90a01a0 100644
--- a/src/session/test/gtest_state_udp_init_to_opening_to_active_to_closing.cpp
+++ b/src/session/test/gtest_state_udp_init_to_opening_to_active_to_closing.cpp
@@ -4,7 +4,6 @@
 #include "tuple.h"
 #include "packet_private.h"
 #include "packet_parser.h"
-#include "snowflake.h"
 #include "session_private.h"
 #include "session_manager.h"
 #include "test_packets.h"
@@ -49,6 +48,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 #if 1
 TEST(UDP_INIT_TO_OPENING_TO_ACTIVE_TO_CLOSING, TEST)
 {
@@ -60,6 +65,7 @@ TEST(UDP_INIT_TO_OPENING_TO_ACTIVE_TO_CLOSING, TEST)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S REQ Packet
     printf("\n=> Packet Parse: UDP C2S REQ packet\n");
@@ -154,11 +160,6 @@ TEST(UDP_INIT_TO_OPENING_TO_ACTIVE_TO_CLOSING, TEST)
 
 int main(int argc, char **argv)
 {
-    struct snowflake_options opt = {
-        .snowflake_base = 1,
-        .snowflake_offset = 2,
-    };
-    snowflake_id_init(&opt);
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
-}
+}
\ No newline at end of file
diff --git a/src/session/test/gtest_state_udp_init_to_opening_to_closing.cpp b/src/session/test/gtest_state_udp_init_to_opening_to_closing.cpp
index f555137..bc59eb1 100644
--- a/src/session/test/gtest_state_udp_init_to_opening_to_closing.cpp
+++ b/src/session/test/gtest_state_udp_init_to_opening_to_closing.cpp
@@ -4,7 +4,6 @@
 #include "tuple.h"
 #include "packet_private.h"
 #include "packet_parser.h"
-#include "snowflake.h"
 #include "session_private.h"
 #include "session_manager.h"
 #include "test_packets.h"
@@ -49,6 +48,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 /******************************************************************************
  * case: UDP init -> opening (by C2S Packet)
  * case: UDP opening -> closing (by timeout)
@@ -65,6 +70,7 @@ TEST(UDP_INIT_TO_OPENING_TO_CLOSING, BY_C2S)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S REQ Packet
     printf("\n=> Packet Parse: UDP C2S REQ packet\n");
@@ -143,6 +149,7 @@ TEST(UDP_INIT_TO_OPENING_TO_CLOSING, BY_S2C)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // S2C RESP Packet
     printf("\n=> Packet Parse: UDP S2C RESP packet\n");
@@ -209,11 +216,6 @@ TEST(UDP_INIT_TO_OPENING_TO_CLOSING, BY_S2C)
 
 int main(int argc, char **argv)
 {
-    struct snowflake_options opt = {
-        .snowflake_base = 1,
-        .snowflake_offset = 2,
-    };
-    snowflake_id_init(&opt);
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
-}
+}
\ No newline at end of file
diff --git a/src/session/test/gtest_timeout_tcp_data.cpp b/src/session/test/gtest_timeout_tcp_data.cpp
index 6037517..47ff9cd 100644
--- a/src/session/test/gtest_timeout_tcp_data.cpp
+++ b/src/session/test/gtest_timeout_tcp_data.cpp
@@ -47,6 +47,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 #if 1
 TEST(TIMEOUT, TCP_TIMEOUT_DATA)
 {
@@ -56,6 +62,7 @@ TEST(TIMEOUT, TCP_TIMEOUT_DATA)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
diff --git a/src/session/test/gtest_timeout_tcp_handshake.cpp b/src/session/test/gtest_timeout_tcp_handshake.cpp
index 638c53f..68d10f5 100644
--- a/src/session/test/gtest_timeout_tcp_handshake.cpp
+++ b/src/session/test/gtest_timeout_tcp_handshake.cpp
@@ -47,6 +47,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 #if 1
 TEST(TIMEOUT, TCP_TIMEOUT_HANDSHAKE)
 {
@@ -56,6 +62,7 @@ TEST(TIMEOUT, TCP_TIMEOUT_HANDSHAKE)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // S2C SYNACK Packet
     printf("\n=> Packet Parse: TCP S2C SYNACK packet\n");
diff --git a/src/session/test/gtest_timeout_tcp_init.cpp b/src/session/test/gtest_timeout_tcp_init.cpp
index 6e12406..7d9e1bb 100644
--- a/src/session/test/gtest_timeout_tcp_init.cpp
+++ b/src/session/test/gtest_timeout_tcp_init.cpp
@@ -47,6 +47,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 #if 1
 TEST(TIMEOUT, TCP_TIMEOUT_INIT)
 {
@@ -56,6 +62,7 @@ TEST(TIMEOUT, TCP_TIMEOUT_INIT)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S SYN Packet
     printf("\n=> Packet Parse: TCP C2S SYN packet\n");
diff --git a/src/session/test/gtest_timeout_udp_data.cpp b/src/session/test/gtest_timeout_udp_data.cpp
index d815ffb..60bb133 100644
--- a/src/session/test/gtest_timeout_udp_data.cpp
+++ b/src/session/test/gtest_timeout_udp_data.cpp
@@ -47,6 +47,12 @@ struct session_manager_options opts = {
     .tcp_reassembly_max_segments = 16,
 };
 
+static uint64_t session_id_generator(uint64_t now_ms __attribute__((unused)))
+{
+    static uint64_t count = 0;
+    return (++count);
+}
+
 #if 1
 TEST(TIMEOUT, UDP_TIMEOUT_DATA1)
 {
@@ -56,6 +62,7 @@ TEST(TIMEOUT, UDP_TIMEOUT_DATA1)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S REQ Packet
     printf("\n=> Packet Parse: UDP C2S REQ packet\n");
@@ -92,6 +99,7 @@ TEST(TIMEOUT, UDP_TIMEOUT_DATA2)
 
     mgr = session_manager_new(&opts, 1);
     EXPECT_TRUE(mgr != NULL);
+    session_manager_set_session_id_generator(mgr, session_id_generator);
 
     // C2S REQ Packet
     printf("\n=> Packet Parse: UDP C2S REQ packet\n");
diff --git a/src/snowflake/CMakeLists.txt b/src/snowflake/CMakeLists.txt
index e68faa6..7ebc441 100644
--- a/src/snowflake/CMakeLists.txt
+++ b/src/snowflake/CMakeLists.txt
@@ -1,5 +1,5 @@
 add_library(snowflake snowflake.cpp)
 target_include_directories(snowflake PUBLIC ${CMAKE_CURRENT_LIST_DIR})
-target_include_directories(snowflake PUBLIC ${CMAKE_SOURCE_DIR}/src/utils)
-target_include_directories(snowflake PUBLIC ${CMAKE_SOURCE_DIR}/include/stellar)
-target_link_libraries(snowflake core)
\ No newline at end of file
+target_link_libraries(snowflake log)
+
+add_subdirectory(test)
\ No newline at end of file
diff --git a/src/snowflake/snowflake.cpp b/src/snowflake/snowflake.cpp
index bea562a..3c1133d 100644
--- a/src/snowflake/snowflake.cpp
+++ b/src/snowflake/snowflake.cpp
@@ -1,57 +1,61 @@
-#include <time.h>
-#include <string.h>
+#include <stdint.h>
+#include <stdlib.h>
 
 #include "log.h"
-#include "utils.h"
-#include "stellar.h"
 #include "snowflake.h"
 
-#define snowflake_LOG_ERROR(format, ...) LOG_ERROR("snowflake", format, ##__VA_ARGS__)
-#define snowflake_LOG_DEBUG(format, ...) LOG_DEBUG("snowflake", format, ##__VA_ARGS__)
+#define SNOWFLAKE_LOG_ERROR(format, ...) LOG_ERROR("snowflake", format, ##__VA_ARGS__)
 
 struct snowflake
 {
-    uint8_t snowflake_base;   // 5bit  [0, 31]
-    uint8_t snowflake_offset; // 7bit  [0, 127]
-    uint64_t device_id;       // 12bit [0, 4095] ( base << 7 | offset )
-    uint64_t thread[MAX_THREAD_NUM];
+    uint8_t worker_base_id;   //  5 bit [0, 31]
+    uint8_t worker_offset_id; //  7 bit [0, 127]
+    uint64_t thread_id;       //  limit 256
+    uint64_t device_id;       // 12 bit [0, 4095] ( base << 7 | offset )
+    uint64_t sequence;
 };
 
-struct snowflake g_snowflake = {};
-
-// return  0: success
-// return -1: failed
-int snowflake_id_init(const struct snowflake_options *opts)
+struct snowflake *snowflake_new(uint16_t thread_id, uint8_t worker_base_id, uint8_t worker_offset_id)
 {
-    memset(&g_snowflake, 0, sizeof(struct snowflake));
-
-    if (opts == NULL)
+    if (thread_id > 255)
     {
-        snowflake_LOG_ERROR("opts is NULL");
-        return -1;
+        SNOWFLAKE_LOG_ERROR("thread_id %u is invalid, range [0, 255]", thread_id);
+        return NULL;
+    }
+    if (worker_base_id > 31)
+    {
+        SNOWFLAKE_LOG_ERROR("worker_base_id %u is invalid, range [0, 31]", worker_base_id);
+        return NULL;
+    }
+    if (worker_offset_id > 127)
+    {
+        SNOWFLAKE_LOG_ERROR("worker_offset_id %u is invalid, range [0, 127]", worker_offset_id);
+        return NULL;
     }
 
-    if (opts->snowflake_base > 31)
+    struct snowflake *sf = (struct snowflake *)calloc(1, sizeof(struct snowflake));
+    if (sf == NULL)
     {
-        snowflake_LOG_ERROR("snowflake_base %u is invalid, range [0, 31]", opts->snowflake_base);
-        return -1;
+        SNOWFLAKE_LOG_ERROR("calloc snowflake failed");
+        return NULL;
     }
 
-    if (opts->snowflake_offset > 127)
+    sf->worker_base_id = worker_base_id;
+    sf->worker_offset_id = worker_offset_id;
+    sf->thread_id = thread_id;
+    sf->device_id = ((worker_base_id << 7) | worker_offset_id) & 0xFFF;
+    sf->sequence = 0;
+
+    return sf;
+}
+
+void snowflake_free(struct snowflake *sf)
+{
+    if (sf != NULL)
     {
-        snowflake_LOG_ERROR("snowflake_offset %u is invalid, range [0, 127]", opts->snowflake_offset);
-        return -1;
+        free(sf);
+        sf = NULL;
     }
-
-    g_snowflake.snowflake_base = opts->snowflake_base;
-    g_snowflake.snowflake_offset = opts->snowflake_offset;
-    g_snowflake.device_id = ((g_snowflake.snowflake_base << 7) | g_snowflake.snowflake_offset) & 0xFFF;
-
-    snowflake_LOG_DEBUG("snowflake_base: %u, snowflake_offset: %u, device_id: %u",
-                        g_snowflake.snowflake_base,
-                        g_snowflake.snowflake_offset,
-                        g_snowflake.device_id);
-    return 0;
 }
 
 /*
@@ -61,20 +65,41 @@ int snowflake_id_init(const struct snowflake_options *opts)
  * | 1bit |  12bit device_id | 8bit thread_id | 28bit timestamp in sec | 15bit sequence per thread |
  * +------+------------------+----------------+------------------------+---------------------------+
  */
-uint64_t snowflake_id_generate(uint64_t now_sec)
-{
+
 #define MAX_ID_PER_THREAD (32768)
 #define MAX_ID_BASE_TIME (268435456L)
 
-    uint64_t thr_idx = (uint16_t)stellar_get_current_thread_index();
+uint64_t snowflake_generate(struct snowflake *sf, uint64_t now_sec)
+{
+    if (sf == NULL)
+    {
+        SNOWFLAKE_LOG_ERROR("snowflake is NULL");
+        return 0;
+    }
 
-    uint64_t global_id = 0;
-    uint64_t id_per_thread = (g_snowflake.thread[thr_idx]++) % MAX_ID_PER_THREAD;
+    uint64_t id = 0;
+    uint64_t id_per_thread = (sf->sequence++) % MAX_ID_PER_THREAD;
     uint64_t id_base_time = now_sec % MAX_ID_BASE_TIME;
-    global_id = (g_snowflake.device_id << 51) |
-                (thr_idx << 43) |
-                (id_base_time << 15) |
-                (id_per_thread);
+    id = (sf->device_id << 51) |
+         (sf->thread_id << 43) |
+         (id_base_time << 15) |
+         (id_per_thread);
 
-    return global_id;
+    return id;
 }
+
+void snowflake_deserialize(uint64_t id, struct snowflake_meta *meta)
+{
+    if (meta == NULL)
+    {
+        return;
+    }
+
+    meta->sequence = id & 0x7FFF;
+    meta->time_cycle = MAX_ID_BASE_TIME;
+    meta->time_relative = (id >> 15) & 0xFFFFFFF;
+    meta->thread_id = (id >> 43) & 0xFF;
+    meta->device_id = (id >> 51) & 0xFFF;
+    meta->worker_base_id = (meta->device_id >> 7) & 0x1F;
+    meta->worker_offset_id = meta->device_id & 0x7F;
+}
\ No newline at end of file
diff --git a/src/snowflake/snowflake.h b/src/snowflake/snowflake.h
index b0b10dd..228b96a 100644
--- a/src/snowflake/snowflake.h
+++ b/src/snowflake/snowflake.h
@@ -7,16 +7,24 @@ extern "C"
 
 #include <stdint.h>
 
-struct snowflake_options
+struct snowflake;
+struct snowflake *snowflake_new(uint16_t thread_id, uint8_t worker_base_id, uint8_t worker_offset_id);
+void snowflake_free(struct snowflake *sf);
+
+struct snowflake_meta
 {
-    uint8_t snowflake_base;
-    uint8_t snowflake_offset;
+    uint64_t sequence;
+    uint64_t time_cycle;
+    uint64_t time_relative;
+    uint16_t thread_id;
+    uint16_t device_id;
+
+    uint8_t worker_base_id;
+    uint8_t worker_offset_id;
 };
 
-// return  0: success
-// return -1: failed
-int snowflake_id_init(const struct snowflake_options *opts);
-uint64_t snowflake_id_generate(uint64_t now_sec);
+uint64_t snowflake_generate(struct snowflake *sf, uint64_t now_sec);
+void snowflake_deserialize(uint64_t id, struct snowflake_meta *meta);
 
 #ifdef __cplusplus
 }
diff --git a/src/snowflake/test/CMakeLists.txt b/src/snowflake/test/CMakeLists.txt
new file mode 100644
index 0000000..307c1e5
--- /dev/null
+++ b/src/snowflake/test/CMakeLists.txt
@@ -0,0 +1,8 @@
+add_executable(gtest_snowflake gtest_snowflake.cpp)
+target_link_libraries(gtest_snowflake snowflake gtest)
+
+add_executable(snowflake_tool snowflake_tool.cpp)
+target_link_libraries(snowflake_tool snowflake)
+
+include(GoogleTest)
+gtest_discover_tests(gtest_snowflake)
\ No newline at end of file
diff --git a/src/snowflake/test/gtest_snowflake.cpp b/src/snowflake/test/gtest_snowflake.cpp
new file mode 100644
index 0000000..78c4374
--- /dev/null
+++ b/src/snowflake/test/gtest_snowflake.cpp
@@ -0,0 +1,48 @@
+#include <gtest/gtest.h>
+
+#include "snowflake.h"
+
+TEST(SNOWFLAKE, GENERATE)
+{
+    uint16_t thread_id = 1;
+    uint8_t worker_base_id = 2;
+    uint8_t worker_offset_id = 3;
+
+    struct snowflake *sf = snowflake_new(thread_id, worker_base_id, worker_offset_id);
+    EXPECT_TRUE(sf != NULL);
+    EXPECT_TRUE(snowflake_generate(sf, 1000) != 0);
+    snowflake_free(sf);
+}
+
+TEST(SNOWFLAKE, DESERIALIZE)
+{
+    uint16_t thread_id = 1;
+    uint8_t worker_base_id = 2;
+    uint8_t worker_offset_id = 3;
+
+    struct snowflake *sf = snowflake_new(thread_id, worker_base_id, worker_offset_id);
+    EXPECT_TRUE(sf != NULL);
+
+    for (uint64_t i = 0; i < 5; i++)
+    {
+        uint64_t id = snowflake_generate(sf, i + 1000);
+        EXPECT_TRUE(id != 0);
+
+        struct snowflake_meta meta = {};
+        snowflake_deserialize(id, &meta);
+        EXPECT_EQ(meta.sequence, i);
+        EXPECT_EQ(meta.time_relative, i + 1000);
+        EXPECT_EQ(meta.thread_id, thread_id);
+        EXPECT_EQ(meta.device_id, (worker_base_id << 7) | worker_offset_id);
+        EXPECT_EQ(meta.worker_base_id, worker_base_id);
+        EXPECT_EQ(meta.worker_offset_id, worker_offset_id);
+    }
+
+    snowflake_free(sf);
+}
+
+int main(int argc, char **argv)
+{
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}
diff --git a/src/snowflake/test/snowflake_tool.cpp b/src/snowflake/test/snowflake_tool.cpp
new file mode 100644
index 0000000..5d0d335
--- /dev/null
+++ b/src/snowflake/test/snowflake_tool.cpp
@@ -0,0 +1,38 @@
+#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "snowflake.h"
+
+int main(int argc, char **argv)
+{
+    if (argc != 2)
+    {
+        printf("Usage: %s <id>\n", argv[0]);
+        return -1;
+    }
+
+    uint64_t id = atoll(argv[1]);
+    struct snowflake_meta meta = {};
+    snowflake_deserialize(id, &meta);
+
+    printf("id              : %lu\n", id);
+    printf("base_id         : %u\n", meta.worker_base_id);
+    printf("offset_id       : %u\n", meta.worker_offset_id);
+    printf("device_id       : %u\n", meta.device_id);
+    printf("thread_id       : %u\n", meta.thread_id);
+    printf("time_cycle      : %lu sec (%lu year)\n", meta.time_cycle, meta.time_cycle / 3600 / 24 / 365);
+    printf("time_relative   : %lu sec\n", meta.time_relative);
+    printf("sequence        : %lu\n", meta.sequence);
+
+    for (int i = 6; i < 10; i++)
+    {
+        char buff[64];
+        time_t tt = meta.time_cycle * i + meta.time_relative;
+        struct tm *tm = localtime(&tt);
+        strftime(buff, sizeof(buff), "%Y-%m-%d %H:%M:%S", tm);
+        printf("\ttime_cycle * %d + time_relative => %s\n", i, buff);
+    }
+
+    return 0;
+}
\ No newline at end of file
diff --git a/test/debug_plugin/debug_plugin.cpp b/test/debug_plugin/debug_plugin.cpp
index 24e905e..6d6f85c 100644
--- a/test/debug_plugin/debug_plugin.cpp
+++ b/test/debug_plugin/debug_plugin.cpp
@@ -1,19 +1,12 @@
-#include <stdio.h>
-#include <errno.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
 #include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
 #include <stdarg.h>
-#include <time.h>
 #include <pthread.h>
-#include <arpa/inet.h>
 
 #include "utils.h"
 #include "packet_dump.h"
 #include "session_private.h"
-#include "stellar/session.h"
-#include "stellar/packet.h"
 #include "stellar/stellar_mq.h"
 #include "stellar/stellar_exdata.h"