diff --git a/example/osfp_example.c b/example/osfp_example.c
index 146587e..2a53ac6 100644
--- a/example/osfp_example.c
+++ b/example/osfp_example.c
@@ -3,6 +3,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <time.h>
+#include <signal.h>
 
 #include <sys/socket.h>
 
@@ -145,6 +146,11 @@ typedef struct Packet_ {
     int vlan_layer;
 } Packet;
 
+typedef struct EthernetHdr_ {
+    uint8_t eth_dst[6];
+    uint8_t eth_src[6];
+    uint16_t eth_type;
+} __attribute__((__packed__)) EthernetHdr;
 
 unsigned char *fp_file_path;
 unsigned char *fp_output_file_path;
@@ -159,6 +165,12 @@ pcap_t *pcap_handle;
 int processed_packet;
 int link_type;
 
+struct osfp_profile_counter identify_profile;
+
+unsigned int identify_failed_count = 0;
+unsigned int identify_count = 0;
+unsigned int result_os_count[OSFP_OS_CLASS_MAX];
+
 void usage(void) {
     fprintf(stderr,
         "Usage: osfp_match [ ...options... ] [ 'filter rule' ]\n"
@@ -172,13 +184,6 @@ void usage(void) {
     exit(1);
 }
 
-typedef struct EthernetHdr_ {
-    uint8_t eth_dst[6];
-    uint8_t eth_src[6];
-    uint16_t eth_type;
-} __attribute__((__packed__)) EthernetHdr;
-
-
 int packet_decode_tcp(Packet *p, const unsigned char *data, unsigned int len)
 {
     int ret = -1;
@@ -434,13 +439,16 @@ void example_detect(struct osfp_db *osfp_db, Packet *p)
     unsigned int tcph_len;
     struct osfp_result *result = NULL;
 
-    printf("Example ipv4 header detect: --------------------------\n");
-
     iph = (struct iphdr *)p->iph;
     ip6h = (struct ip6_hdr *)p->ip6h;
     tcph = (struct tcphdr *)p->tcph;
     tcph_len = tcph->doff << 2;
 
+    osfp_profile_cycle(c1);
+    osfp_profile_cycle(c2);
+
+
+    osfp_profile_get_cycle(c1);
     if (iph) {
         result = osfp_ipv4_identify(osfp_db, iph, tcph, tcph_len);
     } else if (ip6h) {
@@ -448,17 +456,28 @@ void example_detect(struct osfp_db *osfp_db, Packet *p)
     } else {
         goto exit;
     }
+    osfp_profile_get_cycle(c2);
+    osfp_profile_counter_update(&identify_profile, c2 - c1);
+
+    identify_count++;
 
     if (result == NULL) {
+        identify_failed_count++;
         printf("osfp header match failed, erro: %s\n", "?");
         goto exit;
     }
 
-    printf("Connection info: %s:%d -> %s:%d\n", p->srcip, p->sp, p->dstip, p->dp);
-    printf("Most likely os class: %s\n", osfp_result_os_name_get(result));
+    result_os_count[result->likely_os_class]++;
 
-    printf("Details:\n");
-    printf("%s\n", osfp_result_score_detail_export(result));
+    char *json = osfp_result_score_detail_export(result);
+
+    if (1) {
+        printf("Example ipv4 header detect: --------------------------\n");
+        printf("Connection info: %s:%d -> %s:%d\n", p->srcip, p->sp, p->dstip, p->dp);
+        printf("Most likely os class: %s\n", osfp_result_os_name_get(result));
+        printf("Details:\n");
+        printf("%s\n", json);
+    }
 
 exit:
     if (result) {
@@ -499,7 +518,10 @@ void process_packet(char *user, struct pcap_pkthdr *h, u_char *pkt)
     }
 
     // tcp/ip header detect example for user
-    example_detect(osfp_db, p);
+    int i;
+    for (i = 0; i < 1; i++) {
+        example_detect(osfp_db, p);
+    }
 
     printf("---------------------------    processed packet count %d\n", ++processed_packet);
 
@@ -507,10 +529,35 @@ exit:
     return;
 }
 
+static void signal_handler(int signum)
+{
+    printf("profile identify: avg: %lu max: %lu min: %lu curr: %lu total: %lu count: %lu\n",
+            identify_profile.total_cycle / identify_profile.count,
+            identify_profile.max_cycle,
+            identify_profile.min_cycle,
+            identify_profile.curr_cycle,
+            identify_profile.total_cycle,
+            identify_profile.count);
+
+    osfp_profile_print_stats();
+
+    printf("total %u, failed %u\n",
+                identify_count, identify_failed_count);
+    int i;
+    for (i = 0; i < OSFP_OS_CLASS_MAX; i++) {
+        printf("%s: %u\n", osfp_os_class_id_to_name(i), result_os_count[i]);
+    }
+
+    exit(0);
+}
+
 int main(int argc, char *argv[])
 {
     int r;
 
+    signal(SIGINT, signal_handler);
+    signal(SIGTERM, signal_handler);
+
     while ((r = getopt(argc, argv, "+f:i:r:o:d")) != -1) {
         switch(r) {
             case 'f':
@@ -621,6 +668,8 @@ int main(int argc, char *argv[])
         osfp_log_level_set(OSFP_LOG_LEVEL_DEBUG);
     }
 
+    osfp_profile_set(1);
+
     struct osfp_db *osfp_db = osfp_db_new(fp_file_path);
     if (osfp_db == NULL) {
         printf("could not create osfp context. fingerprints file: %s\n", fp_file_path);
diff --git a/pcap/synmerge.pcap b/pcap/synmerge.pcap
new file mode 100644
index 0000000..a3a9984
Binary files /dev/null and b/pcap/synmerge.pcap differ
diff --git a/src/osfp.c b/src/osfp.c
index ec9a78f..e822436 100644
--- a/src/osfp.c
+++ b/src/osfp.c
@@ -94,6 +94,10 @@ char *osfp_result_score_detail_export(struct osfp_result *result)
     cJSON *array;
     cJSON *os_score;
 
+    osfp_profile_cycle(c1);
+    osfp_profile_cycle(c2);
+    osfp_profile_get_cycle(c1);
+
     if (result == NULL) {
         goto exit;
     }
@@ -139,6 +143,10 @@ exit:
     if (root) {
         cJSON_Delete(root);
     }
+    if (result_str) {
+        osfp_profile_get_cycle(c2);
+        osfp_profile_counter_update(&osfp_profile_result_export, c2 - c1);
+    }
     return result_str;
 }
 
@@ -159,21 +167,33 @@ struct osfp_result *osfp_ipv4_identify(struct osfp_db *db, struct iphdr* l3_hdr,
     struct osfp_os_class_score os_class_score;
     struct osfp_result *result;
 
+    osfp_profile_cycle(c1);
+    osfp_profile_cycle(c2);
+
     if (db == NULL || l3_hdr == NULL || l4_hdr == NULL || l4_hdr == 0) {
         goto exit;
     }
 
+    osfp_profile_get_cycle(c1);
     ret = osfp_fingerprinting((unsigned char *)l3_hdr, (unsigned char *)l4_hdr, (unsigned int)l4_hdr_len, &fp, 4);
+    osfp_profile_get_cycle(c2);
+    osfp_profile_counter_update(&osfp_profile_fingerprinting, c2 - c1);
     if (ret != 0) {
         goto exit;
     }
 
+    osfp_profile_get_cycle(c1);
     ret = osfp_score_db_score(db->score_db, 0, &fp, &os_class_score);
+    osfp_profile_get_cycle(c2);
+    osfp_profile_counter_update(&osfp_profile_score, c2 - c1);
     if (ret != 0) {
         goto exit;
     }
 
+    osfp_profile_get_cycle(c1);
     result = osfp_result_build(&os_class_score);
+    osfp_profile_get_cycle(c2);
+    osfp_profile_counter_update(&osfp_profile_result_build, c2 - c1);
     if (result == NULL) {
         goto exit;
     }
@@ -190,7 +210,7 @@ struct osfp_result *osfp_ipv6_identify(struct osfp_db *db, struct ip6_hdr* l3_hd
     struct osfp_os_class_score os_class_score;
     struct osfp_result *result;
 
-    if (db == NULL || l3_hdr == NULL || l4_hdr == NULL) {
+    if (db == NULL || l3_hdr == NULL || l4_hdr == NULL || l4_hdr_len == 0) {
         goto exit;
     }
 
@@ -225,7 +245,7 @@ struct osfp_result *osfp_json_identify(struct osfp_db *db, const char *json_str)
         goto exit;
     }
 
-    ret = osfp_fingerprint_from_json(&fp, json_str);
+    ret = osfp_fingerprint_from_json(&fp, (char *)json_str);
     if (ret != 0) {
         goto exit;
     }
diff --git a/src/osfp_common.c b/src/osfp_common.c
index ab76c67..fa80b34 100644
--- a/src/osfp_common.c
+++ b/src/osfp_common.c
@@ -2,6 +2,8 @@
 
 #include "osfp.h"
 
+unsigned int osfp_profile_enable;
+
 const char *os_class_name[OSFP_OS_CLASS_MAX] = {
     OSFP_OS_CLASS_NAME_UNKNOWN,
     OSFP_OS_CLASS_NAME_WINDOWS,
@@ -12,6 +14,54 @@ const char *os_class_name[OSFP_OS_CLASS_MAX] = {
     OSFP_OS_CLASS_NAME_OTHERS
 };
 
+struct osfp_profile_counter osfp_profile_fingerprinting;
+struct osfp_profile_counter osfp_profile_score;
+struct osfp_profile_counter osfp_profile_result_build;
+struct osfp_profile_counter osfp_profile_result_export;
+
+void osfp_profile_counter_print(struct osfp_profile_counter *profile, const char *name)
+{
+    printf("profile %s: avg: %lu max: %lu min: %lu curr: %lu total: %lu count: %lu\n",
+            name, 
+            profile->total_cycle / profile->count,
+            profile->max_cycle,
+            profile->min_cycle,
+            profile->curr_cycle,
+            profile->total_cycle,
+            profile->count);
+}
+void osfp_profile_counter_update(struct osfp_profile_counter *profile, unsigned long long curr_cycle)
+{
+    profile->count++;
+    profile->curr_cycle = curr_cycle;
+    profile->total_cycle += curr_cycle;
+
+    if (profile->min_cycle == 0) {
+        profile->min_cycle = curr_cycle;
+    } else {
+        if (profile->min_cycle > curr_cycle) {
+            profile->min_cycle = curr_cycle;
+        }
+    }
+
+    if (profile->max_cycle < curr_cycle) {
+        profile->max_cycle = curr_cycle;
+    }
+}
+
+void osfp_profile_print_stats(void)
+{
+    osfp_profile_counter_print(&osfp_profile_fingerprinting, "fingerprinting");
+    osfp_profile_counter_print(&osfp_profile_score, "score");
+    osfp_profile_counter_print(&osfp_profile_result_build, "result_build");
+    osfp_profile_counter_print(&osfp_profile_result_export, "result export");
+}
+
+void osfp_profile_set(unsigned int enabled)
+{
+    osfp_profile_enable = enabled;
+}
+
 enum osfp_os_class_id osfp_os_class_name_to_id(char *name)
 {
     enum osfp_os_class_id os_class;
@@ -33,8 +83,3 @@ enum osfp_os_class_id osfp_os_class_name_to_id(char *name)
     return os_class;
 }
 
-const char *osfp_os_class_id_to_name(enum osfp_os_class_id os_class)
-{
-    return os_class_name[os_class];
-}
-
diff --git a/src/osfp_common.h b/src/osfp_common.h
index 023a2ee..3b25ba1 100644
--- a/src/osfp_common.h
+++ b/src/osfp_common.h
@@ -39,11 +39,35 @@ static inline unsigned long long osfp_rdtsc(void)
 	return tsc.tsc_64;
 }
 
+extern unsigned int osfp_profile_enable;
+
 #define osfp_profile_cycle(x) volatile unsigned long long x = 0
 #define osfp_profile_get_cycle(x) do { \
-        x = osfp_rdtsc(); \
+        if (__builtin_expect(!!(osfp_profile_enable), 0)) { \
+            x = osfp_rdtsc(); \
+        } else { \
+            x = 0; \
+        } \
     } while(0)
 
+struct osfp_profile_counter {
+    unsigned long long count;
+    unsigned long long curr_cycle;
+    unsigned long long max_cycle;
+    unsigned long long min_cycle;
+    unsigned long long total_cycle;
+};
+
+extern struct osfp_profile_counter osfp_profile_fingerprinting;
+extern struct osfp_profile_counter osfp_profile_score;
+extern struct osfp_profile_counter osfp_profile_result_build;
+extern struct osfp_profile_counter osfp_profile_result_export;
+
+void osfp_profile_counter_update(struct osfp_profile_counter *profile, unsigned long long curr_cycle);
+void osfp_profile_print_stats(void);
+void osfp_profile_set(unsigned int enabled);
+
+
 #define OSFP_BIT_U32(n) (1UL << (n))
 
 #define OSFP_PERCENTILE 100
@@ -171,7 +195,12 @@ struct osfp_db {
     void *score_db;       // 分数数据库指针
 };
 
-const char *osfp_os_class_id_to_name(enum osfp_os_class_id os_class);
 enum osfp_os_class_id osfp_os_class_name_to_id(char *name);
 
+extern const char *os_class_name[OSFP_OS_CLASS_MAX];
+static inline const char *osfp_os_class_id_to_name(enum osfp_os_class_id os_class)
+{
+    return os_class_name[os_class];
+}
+
 #endif
diff --git a/src/osfp_fingerprint.c b/src/osfp_fingerprint.c
index 3c212e6..6d4cc01 100644
--- a/src/osfp_fingerprint.c
+++ b/src/osfp_fingerprint.c
@@ -88,6 +88,30 @@ static unsigned int compute_ip_ttl(unsigned int ip_ttl)
     return ip_ttl;
 }
 
+static void osfp_fingerprint_setup_field(struct osfp_fingerprint *fp, enum osfp_field_id field_id, void *value, unsigned int len)
+{
+    fp->fields[field_id].name = osfp_fingerprint_get_field_name(field_id);
+    fp->fields[field_id].enabled = 1;
+
+    if (fp->value_buffer_used + len <= sizeof(fp->value_buffer)) {
+        memcpy(fp->value_buffer + fp->value_buffer_used, value, len);
+        fp->fields[field_id].value = fp->value_buffer + fp->value_buffer_used;
+        fp->fields[field_id].value_len = len;
+        fp->value_buffer_used += len;
+    } else {
+        fp->fields[field_id].value = NULL;
+        fp->fields[field_id].value_len = 0;
+    }
+}
+
+static void osfp_fingerprint_init_field(struct osfp_fingerprint *fp, enum osfp_field_id field_id)
+{
+    fp->fields[field_id].name = osfp_fingerprint_get_field_name(field_id);
+    fp->fields[field_id].enabled = 0;
+    fp->fields[field_id].value = NULL;
+    fp->fields[field_id].value_len = 0;
+}
+
 static unsigned int decode_tcp_options(struct osfp_tcp_opt *tcp_opts, unsigned int max_opt_cnt, unsigned char *data, unsigned int len)
 {
     unsigned int offset = 0;
@@ -125,6 +149,186 @@ static unsigned int decode_tcp_options(struct osfp_tcp_opt *tcp_opts, unsigned i
     return tcp_opt_cnt;
 }
 
+static int osfp_fingerprinting_tcp_option(unsigned char *opt_data, unsigned int opt_len, struct osfp_fingerprint *fp)
+{
+    int ret,i;
+
+    unsigned int tcp_mss;
+    unsigned int tcp_ws;
+    unsigned int tcp_ter;
+    unsigned int tcp_opt_cnt;
+    struct osfp_tcp_opt tcp_opts[OSFP_TCP_OPTMAX];
+
+    char options[OSFP_TCP_OPTLENMAX];
+    char options_ordered[OSFP_TCP_OPTLENMAX];
+    unsigned int offset = 0;
+    unsigned int maxoffset = sizeof(options) - 3; //for shortest "E,"
+    unsigned int ordered_offset = 0;
+    unsigned int ordered_maxoffset = sizeof(options_ordered) - 1;
+
+    if (opt_data == NULL || opt_len == 0 || fp == NULL) {
+        goto exit;
+    }
+
+    tcp_opt_cnt = decode_tcp_options(tcp_opts, OSFP_TCP_OPTMAX, opt_data, opt_len);
+
+    for (i = 0; i < tcp_opt_cnt && offset < maxoffset && ordered_offset < ordered_maxoffset; i++) {
+        struct osfp_tcp_opt *opt = &tcp_opts[i];
+
+        char letter = option_to_ascii(opt->type);
+        options[offset++] = letter;
+        options_ordered[ordered_offset++] = letter;
+
+        switch (opt->type) {
+            case OSFP_TCP_OPT_EOL:
+            case OSFP_TCP_OPT_NOP:
+                break;
+            case OSFP_TCP_OPT_MSS:
+                if (opt->len != OSFP_TCP_OPT_MSS_LEN) {
+                    break;
+                }
+                tcp_mss = (unsigned int)ntohs(*(unsigned short *)opt->data);
+                osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_MSS, &tcp_mss, sizeof(tcp_mss));
+                ret = snprintf(options + offset, sizeof(options), "%u", tcp_mss);
+                if (ret < 0 || offset + ret > maxoffset) {
+                    break;
+                }
+                offset += ret;
+                break;
+            case OSFP_TCP_OPT_WSCALE:
+                if (opt->len != OSFP_TCP_OPT_WS_LEN) {
+                    break;
+                }
+                tcp_ws = (unsigned int)*(unsigned char *)opt->data;
+                osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_WINDOW_SCALING, &tcp_ws, sizeof(tcp_ws));
+                ret = snprintf(options + offset, sizeof(options), "%u", tcp_ws);
+                if (ret < 0 || offset + ret > maxoffset) {
+                    break;
+                }
+                offset += ret;
+                break;
+            case OSFP_TCP_OPT_TIMESTAMP:
+                if (opt->len != OSFP_TCP_OPT_TS_LEN) {
+                    break;
+                }
+                tcp_ter = ntohl(*(unsigned int *)(opt->data + 4));
+                osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_TIMESTAMP_ECHO_REPLY, &tcp_ter, sizeof(tcp_ter));
+                ret = snprintf(options + offset, sizeof(options), "%u", tcp_ter);
+                if (ret < 0 || offset + ret > maxoffset) {
+                    break;
+                }
+                offset += ret;
+                break;
+            case OSFP_TCP_OPT_SACKOK:
+            case OSFP_TCP_OPT_SACK:
+            case OSFP_TCP_OPT_ECHO:
+            case OSFP_TCP_OPT_ECHOREPLY:
+            case OSFP_TCP_OPT_POCONN:
+            case OSFP_TCP_OPT_POSVC:
+                break;
+            default:
+                ret = snprintf(options + offset, sizeof(options), "%u", opt->type);
+                if (ret < 0 || offset + ret > maxoffset) {
+                    break;
+                }
+                offset += ret;
+        }
+
+        options[offset++] = ',';
+        options[offset] = 0;
+        options_ordered[ordered_offset] = 0;
+    }
+
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_OPTIONS, options, strlen(options) + 1);
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_OPTIONS_ORDERED, options_ordered, strlen(options_ordered) + 1);
+
+    return 0;
+exit:
+    return -1;
+}
+
+static int osfp_fingerprinting_tcp(struct tcphdr *tcph, unsigned int tcph_len, struct osfp_fingerprint *fp)
+{
+    unsigned int tcp_off;
+    unsigned int tcp_window_size;
+    unsigned int tcp_flags;
+
+    if (tcph == NULL || tcph_len > OSFP_TCP_DATA_OFF_MAX || fp == NULL) {
+        goto exit;
+    }
+
+    tcp_off = tcph->doff << 2;
+    tcp_window_size = ntohs(tcph->window);
+    tcp_flags = *((unsigned char *)&tcph->ack_seq + 5);
+
+    if (tcp_off != tcph_len) {
+        goto exit;
+    }
+
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_OFF, &tcp_off, sizeof(tcp_off));
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_WINDOW_SIZE, &tcp_window_size, sizeof(tcp_window_size));
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_FLAGS, &tcp_flags, sizeof(tcp_flags));
+
+    osfp_fingerprint_init_field(fp, OSFP_FIELD_TCP_TIMESTAMP);
+    osfp_fingerprint_init_field(fp, OSFP_FIELD_TCP_TIMESTAMP_ECHO_REPLY);
+    osfp_fingerprint_init_field(fp, OSFP_FIELD_TCP_WINDOW_SCALING);
+    osfp_fingerprint_init_field(fp, OSFP_FIELD_TCP_MSS);
+    osfp_fingerprint_init_field(fp, OSFP_FIELD_TCP_OPTIONS);
+    osfp_fingerprint_init_field(fp, OSFP_FIELD_TCP_OPTIONS_ORDERED);
+
+    // tcp options
+    if (tcp_off > OSFP_TCP_HEADER_LEN) {
+        osfp_fingerprinting_tcp_option((unsigned char *)tcph + OSFP_TCP_HEADER_LEN, tcp_off - OSFP_TCP_HEADER_LEN, fp);
+    }
+
+    return 0;
+exit:
+    return -1;
+}
+
+static int osfp_fingerprinting_ipv4(struct iphdr *iph, struct osfp_fingerprint *fp)
+{
+    if (iph == NULL || fp == NULL) {
+        goto exit;
+    }
+
+    unsigned int ip_id = !!iph->id;
+    unsigned int ip_tos = iph->tos;
+    unsigned int ip_total_length = ntohs(iph->tot_len);
+    unsigned int ip_ttl = compute_ip_ttl(iph->ttl);
+
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_ID, &ip_id, sizeof(ip_id));
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TOS, &ip_tos, sizeof(ip_tos));
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TOTAL_LENGTH, &ip_total_length, sizeof(ip_total_length));
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TTL, &ip_ttl, sizeof(ip_ttl));
+
+    return 0;
+exit:
+    return -1;
+}
+
+static int osfp_fingerprinting_ipv6(struct ip6_hdr *iph, struct osfp_fingerprint *fp)
+{
+    if (iph == NULL || fp == NULL) {
+        goto exit;
+    }
+
+    //unsigned int ip_id = 0;
+    //unsigned int ip_tos = 0;
+    unsigned int ip_total_length = OSFP_IPV6_HEADER_LEN + ntohs(iph->ip6_ctlun.ip6_un1.ip6_un1_plen);
+    unsigned int ip_ttl = compute_ip_ttl(iph->ip6_ctlun.ip6_un1.ip6_un1_hlim);
+
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TOTAL_LENGTH, &ip_total_length, sizeof(ip_total_length));
+    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TTL, &ip_ttl, sizeof(ip_ttl));
+
+    osfp_fingerprint_init_field(fp, OSFP_FIELD_IP_ID);
+    osfp_fingerprint_init_field(fp, OSFP_FIELD_IP_TOS);
+
+    return 0;
+exit:
+    return -1;
+}
+
 int osfp_fingerprint_to_json_buf(struct osfp_fingerprint *fp, char *strbuf, unsigned int buf_len, unsigned int format)
 {
     int rlen = 0, ret, i;
@@ -222,214 +426,6 @@ exit:
     return ret;
 }
 
-unsigned int osfp_fingerprint_get_field_enabled(enum osfp_field_id field_id)
-{
-    return fp_fields[field_id].enabled;
-}
-
-unsigned int osfp_fingerprint_get_field_importance(enum osfp_field_id field_id)
-{
-    return fp_fields[field_id].importance;
-}
-
-const char *osfp_fingerprint_get_field_name(enum osfp_field_id field_id)
-{
-    return fp_fields[field_id].name;
-}
-
-unsigned int osfp_fingerprint_get_field_type(enum osfp_field_id field_id)
-{
-    return fp_fields[field_id].type;
-}
-
-void osfp_fingerprint_setup_field(struct osfp_fingerprint *fp, enum osfp_field_id field_id, void *value, unsigned int len)
-{
-    fp->fields[field_id].name = osfp_fingerprint_get_field_name(field_id);
-    fp->fields[field_id].enabled = 1;
-
-    if (fp->value_buffer_used + len <= sizeof(fp->value_buffer)) {
-        memcpy(fp->value_buffer + fp->value_buffer_used, value, len);
-        fp->fields[field_id].value = fp->value_buffer + fp->value_buffer_used;
-        fp->fields[field_id].value_len = len;
-        fp->value_buffer_used += len;
-    } else {
-        fp->fields[field_id].value = NULL;
-        fp->fields[field_id].value_len = 0;
-    }
-}
-
-int osfp_fingerprinting_tcp_option(unsigned char *opt_data, unsigned int opt_len, struct osfp_fingerprint *fp)
-{
-    int ret,i;
-
-    unsigned int tcp_mss;
-    unsigned int tcp_ws;
-    unsigned int tcp_ter;
-    unsigned int tcp_opt_cnt;
-    struct osfp_tcp_opt tcp_opts[OSFP_TCP_OPTMAX];
-
-    char options[OSFP_TCP_OPTLENMAX];
-    char options_ordered[OSFP_TCP_OPTLENMAX];
-    unsigned int offset = 0;
-    unsigned int maxoffset = sizeof(options) - 3; //for shortest "E,"
-    unsigned int ordered_offset = 0;
-    unsigned int ordered_maxoffset = sizeof(options_ordered) - 1;
-
-    if (opt_data == NULL || opt_len == 0 || fp == NULL) {
-        goto exit;
-    }
-
-    tcp_opt_cnt = decode_tcp_options(tcp_opts, OSFP_TCP_OPTMAX, opt_data, opt_len);
-
-    for (i = 0; i < tcp_opt_cnt && offset < maxoffset && ordered_offset < ordered_maxoffset; i++) {
-        struct osfp_tcp_opt *opt = &tcp_opts[i];
-
-        char letter = option_to_ascii(opt->type);
-        options[offset++] = letter;
-        options_ordered[ordered_offset++] = letter;
-
-        switch (opt->type) {
-            case OSFP_TCP_OPT_EOL:
-            case OSFP_TCP_OPT_NOP:
-                break;
-            case OSFP_TCP_OPT_MSS:
-                if (opt->len != OSFP_TCP_OPT_MSS_LEN) {
-                    break;
-                }
-                tcp_mss = (unsigned int)ntohs(*(unsigned short *)opt->data);
-                osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_MSS, &tcp_mss, sizeof(tcp_mss));
-                ret = snprintf(options + offset, sizeof(options), "%u", tcp_mss);
-                if (ret < 0 || offset + ret > maxoffset) {
-                    break;
-                }
-                offset += ret;
-                break;
-            case OSFP_TCP_OPT_WSCALE:
-                if (opt->len != OSFP_TCP_OPT_WS_LEN) {
-                    break;
-                }
-                tcp_ws = (unsigned int)*(unsigned char *)opt->data;
-                osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_WINDOW_SCALING, &tcp_ws, sizeof(tcp_ws));
-                ret = snprintf(options + offset, sizeof(options), "%u", tcp_ws);
-                if (ret < 0 || offset + ret > maxoffset) {
-                    break;
-                }
-                offset += ret;
-                break;
-            case OSFP_TCP_OPT_TIMESTAMP:
-                if (opt->len != OSFP_TCP_OPT_TS_LEN) {
-                    break;
-                }
-                tcp_ter = ntohl(*(unsigned int *)(opt->data + 4));
-                osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_TIMESTAMP_ECHO_REPLY, &tcp_ter, sizeof(tcp_ter));
-                ret = snprintf(options + offset, sizeof(options), "%u", tcp_ter);
-                if (ret < 0 || offset + ret > maxoffset) {
-                    break;
-                }
-                offset += ret;
-                break;
-            case OSFP_TCP_OPT_SACKOK:
-            case OSFP_TCP_OPT_SACK:
-            case OSFP_TCP_OPT_ECHO:
-            case OSFP_TCP_OPT_ECHOREPLY:
-            case OSFP_TCP_OPT_POCONN:
-            case OSFP_TCP_OPT_POSVC:
-                break;
-            default:
-                ret = snprintf(options + offset, sizeof(options), "%u", opt->type);
-                if (ret < 0 || offset + ret > maxoffset) {
-                    break;
-                }
-                offset += ret;
-        }
-
-        options[offset++] = ',';
-        options[offset] = 0;
-        options_ordered[ordered_offset] = 0;
-    }
-
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_OPTIONS, options, strlen(options) + 1);
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_OPTIONS_ORDERED, options_ordered, strlen(options_ordered) + 1);
-
-    return 0;
-exit:
-    return -1;
-}
-
-int osfp_fingerprinting_tcp(struct tcphdr *tcph, unsigned int tcph_len, struct osfp_fingerprint *fp)
-{
-    unsigned int tcp_off;
-    unsigned int tcp_window_size;
-    unsigned int tcp_flags;
-
-    if (tcph == NULL || tcph_len > OSFP_TCP_DATA_OFF_MAX || fp == NULL) {
-        goto exit;
-    }
-
-    tcp_off = tcph->doff << 2;
-    tcp_window_size = ntohs(tcph->window);
-    tcp_flags = *((unsigned char *)&tcph->ack_seq + 5);
-
-    if (tcp_off != tcph_len) {
-        goto exit;
-    }
-
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_OFF, &tcp_off, sizeof(tcp_off));
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_WINDOW_SIZE, &tcp_window_size, sizeof(tcp_window_size));
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_TCP_FLAGS, &tcp_flags, sizeof(tcp_flags));
-
-    // tcp options
-    if (tcp_off > OSFP_TCP_HEADER_LEN) {
-        osfp_fingerprinting_tcp_option((unsigned char *)tcph + OSFP_TCP_HEADER_LEN, tcp_off - OSFP_TCP_HEADER_LEN, fp);
-    }
-
-    return 0;
-exit:
-    return -1;
-}
-
-int osfp_fingerprinting_ipv4(struct iphdr *iph, struct osfp_fingerprint *fp)
-{
-    if (iph == NULL || fp == NULL) {
-        goto exit;
-    }
-
-    unsigned int ip_id = !!iph->id;
-    unsigned int ip_tos = iph->tos;
-    unsigned int ip_total_length = ntohs(iph->tot_len);
-    unsigned int ip_ttl = compute_ip_ttl(iph->ttl);
-
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_ID, &ip_id, sizeof(ip_id));
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TOS, &ip_tos, sizeof(ip_tos));
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TOTAL_LENGTH, &ip_total_length, sizeof(ip_total_length));
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TTL, &ip_ttl, sizeof(ip_ttl));
-
-    return 0;
-exit:
-    return -1;
-}
-
-int osfp_fingerprinting_ipv6(struct ip6_hdr *iph, struct osfp_fingerprint *fp)
-{
-    if (iph == NULL || fp == NULL) {
-        goto exit;
-    }
-
-    //unsigned int ip_id = 0;
-    //unsigned int ip_tos = 0;
-    unsigned int ip_total_length = OSFP_IPV6_HEADER_LEN + ntohs(iph->ip6_ctlun.ip6_un1.ip6_un1_plen);
-    unsigned int ip_ttl = compute_ip_ttl(iph->ip6_ctlun.ip6_un1.ip6_un1_hlim);
-
-    //osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_ID, &ip_id, sizeof(ip_id));
-    //osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TOS, &ip_tos, sizeof(ip_tos));
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TOTAL_LENGTH, &ip_total_length, sizeof(ip_total_length));
-    osfp_fingerprint_setup_field(fp, OSFP_FIELD_IP_TTL, &ip_ttl, sizeof(ip_ttl));
-
-    return 0;
-exit:
-    return -1;
-}
-
 int osfp_fingerprinting(unsigned char *iph, unsigned char *tcph, unsigned int tcph_len, struct osfp_fingerprint *fp, unsigned int ip_version)
 {
     int ret = OSFP_EINVAL;
@@ -438,7 +434,7 @@ int osfp_fingerprinting(unsigned char *iph, unsigned char *tcph, unsigned int tc
         goto exit;
     }
 
-    memset(fp, 0, sizeof(struct osfp_fingerprint));
+    fp->value_buffer_used = 0;
 
     switch (ip_version) {
         case 4:
diff --git a/src/osfp_fingerprint.h b/src/osfp_fingerprint.h
index 59e697d..0584329 100644
--- a/src/osfp_fingerprint.h
+++ b/src/osfp_fingerprint.h
@@ -43,20 +43,30 @@ struct osfp_fingerprint {
     unsigned int                value_buffer_used;
 };
 
+extern struct osfp_fingerprint_field fp_fields[OSFP_FIELD_MAX];
+
+static inline unsigned int osfp_fingerprint_get_field_enabled(enum osfp_field_id field_id)
+{
+    return fp_fields[field_id].enabled;
+}
+
+static inline unsigned int osfp_fingerprint_get_field_importance(enum osfp_field_id field_id)
+{
+    return fp_fields[field_id].importance;
+}
+
+static inline const char *osfp_fingerprint_get_field_name(enum osfp_field_id field_id)
+{
+    return fp_fields[field_id].name;
+}
+
+static inline unsigned int osfp_fingerprint_get_field_type(enum osfp_field_id field_id)
+{
+    return fp_fields[field_id].type;
+}
+
 int osfp_fingerprint_from_json(struct osfp_fingerprint *fp, char *json_str);
 int osfp_fingerprint_to_json_buf(struct osfp_fingerprint *fp, char *strbuf, unsigned int buf_len, unsigned int format);
-
-void osfp_fingerprint_setup_field(struct osfp_fingerprint *fp, enum osfp_field_id field_id, void *value, unsigned int len);
-
-const char *osfp_fingerprint_get_field_name(enum osfp_field_id field_id);
-unsigned int osfp_fingerprint_get_field_enabled(enum osfp_field_id field_id);
-unsigned int osfp_fingerprint_get_field_importance(enum osfp_field_id field_id);
-unsigned int osfp_fingerprint_get_field_type(enum osfp_field_id field_id);
-
-int osfp_fingerprinting_tcp_option(unsigned char *pkt, unsigned int pktlen, struct osfp_fingerprint *fp);
-int osfp_fingerprinting_tcp(struct tcphdr *tcph, unsigned int tcph_len, struct osfp_fingerprint *fp);
-int osfp_fingerprinting_ipv4(struct iphdr *iph, struct osfp_fingerprint *fp);
-int osfp_fingerprinting_ipv6(struct ip6_hdr *iph, struct osfp_fingerprint *fp);
 int osfp_fingerprinting(unsigned char *iph, unsigned char *tcph, unsigned int tcph_len, struct osfp_fingerprint *fp, unsigned int ip_version);
 
 #ifdef UNITTEST
diff --git a/src/osfp_score_db.c b/src/osfp_score_db.c
index 2e38cde..76b0ba6 100644
--- a/src/osfp_score_db.c
+++ b/src/osfp_score_db.c
@@ -26,7 +26,7 @@ struct osfp_score_db_hash_data {
     struct osfp_score_db_hash_element  *hash_head;
 };
 
-int osfp_score_db_array_add(void *data, struct osfp_os_class_score *os_class_score, void *value, unsigned int len)
+static int osfp_score_db_array_add(void *data, struct osfp_os_class_score *os_class_score, void *value, unsigned int len)
 {
     int ret = -1, i;
     unsigned int index;
@@ -55,7 +55,7 @@ exit:
     return ret;
 }
 
-struct osfp_os_class_score *osfp_score_db_array_match(void *data, void *value, unsigned int len)
+static struct osfp_os_class_score *osfp_score_db_array_match(void *data, void *value, unsigned int len)
 {
     unsigned int index;
     struct osfp_score_db_array_data *array_data = (struct osfp_score_db_array_data *)data;
@@ -77,7 +77,7 @@ struct osfp_os_class_score *osfp_score_db_array_match(void *data, void *value, u
     return &((array_data->array_head)[index]);
 }
 
-void *osfp_score_db_array_create(void)
+static void *osfp_score_db_array_create(void)
 {
     struct osfp_score_db_array_data *array_data = calloc(1, sizeof(struct osfp_score_db_array_data));
     if (array_data == NULL) {
@@ -95,7 +95,7 @@ void *osfp_score_db_array_create(void)
     return (void *)array_data;
 }
 
-void osfp_score_db_array_destroy(void *data) {
+static void osfp_score_db_array_destroy(void *data) {
     struct osfp_score_db_array_data *array_data = (struct osfp_score_db_array_data *)data;
 
     if (array_data) {
@@ -106,7 +106,7 @@ void osfp_score_db_array_destroy(void *data) {
     }
 }
 
-int osfp_score_db_hash_add(void *data, struct osfp_os_class_score *os_class_score, void *value, unsigned int len)
+static int osfp_score_db_hash_add(void *data, struct osfp_os_class_score *os_class_score, void *value, unsigned int len)
 {
     int ret = -1, i;
     struct osfp_score_db_hash_data *hash_data = (struct osfp_score_db_hash_data *)data;
@@ -142,7 +142,7 @@ exit:
     return ret;
 }
 
-struct osfp_os_class_score *osfp_score_db_hash_match(void *data, void *value, unsigned int len)
+static struct osfp_os_class_score *osfp_score_db_hash_match(void *data, void *value, unsigned int len)
 {
     struct osfp_score_db_hash_data *hash_data = (struct osfp_score_db_hash_data *)data;
     struct osfp_score_db_hash_element *element = NULL;
@@ -163,12 +163,12 @@ struct osfp_os_class_score *osfp_score_db_hash_match(void *data, void *value, un
     return element->score;
 }
 
-void *osfp_score_db_hash_create(void)
+static void *osfp_score_db_hash_create(void)
 {
     return (void*)calloc(1, sizeof(struct osfp_score_db_hash_data));
 }
 
-void osfp_score_db_hash_destroy(void *data) {
+static void osfp_score_db_hash_destroy(void *data) {
     struct osfp_score_db_hash_data *hash_data = (struct osfp_score_db_hash_data *)data;
     struct osfp_score_db_hash_element *element = NULL;
     struct osfp_score_db_hash_element *tmp = NULL;
@@ -192,55 +192,7 @@ void osfp_score_db_hash_destroy(void *data) {
     }
 }
 
-char *osfp_score_db_read_file(char *fp_file)
-{
-    int ret = -1;
-    char *file_buffer = NULL;
-    unsigned int file_len = 0;
-    FILE *fp = NULL;
-    struct stat st;
-
-    if (0 > stat(fp_file, &st)) {
-        osfp_log_error("stat() failed on '%s'.\n", fp_file);
-        goto exit;
-    }
-
-    if (st.st_size == 0) { 
-        osfp_log_error("Empty file: '%s'.\n", fp_file);
-        goto exit;
-    }
-
-    file_len = (unsigned int)st.st_size;
-    file_buffer = malloc(file_len + 1);
-    if (file_buffer == NULL) {
-        osfp_log_error("Not enough memory for file buffer. file name: '%s'\n",fp_file);
-        goto exit;
-    }
-
-    fp = fopen(fp_file, "r");
-    if (fp == NULL) {
-        osfp_log_error("Cannot open '%s' for reading.\n", fp_file);
-        goto exit;
-    }
-
-    ret = fread(file_buffer, 1, file_len, fp);
-    if (ret < 0) {
-        osfp_log_error("fread() failed on '%s'.\n", fp_file);
-        free(file_buffer);
-        fclose(fp);
-        goto exit;
-    }
-
-    fclose(fp);
-
-    file_buffer[file_len] = 0;
-
-    return file_buffer;
-exit:
-    return NULL;
-}
-
-int osfp_score_db_load_field(struct osfp_field_score_db *db, cJSON *field, enum osfp_os_class_id os_class)
+static int osfp_score_db_load_field(struct osfp_field_score_db *db, cJSON *field, enum osfp_os_class_id os_class)
 {
     int ret = -1;
     struct osfp_os_class_score os_class_score = {0};
@@ -278,7 +230,7 @@ exit:
     return ret;
 }
 
-int osfp_score_db_load_entry(struct osfp_score_db *score_db, cJSON *entry)
+static int osfp_score_db_load_entry(struct osfp_score_db *score_db, cJSON *entry)
 {
     int ret = -1, i;
     cJSON *field = NULL;
@@ -332,6 +284,54 @@ exit:
     return ret;
 }
 
+char *osfp_score_db_read_file(char *fp_file)
+{
+    int ret = -1;
+    char *file_buffer = NULL;
+    unsigned int file_len = 0;
+    FILE *fp = NULL;
+    struct stat st;
+
+    if (0 > stat(fp_file, &st)) {
+        osfp_log_error("stat() failed on '%s'.\n", fp_file);
+        goto exit;
+    }
+
+    if (st.st_size == 0) { 
+        osfp_log_error("Empty file: '%s'.\n", fp_file);
+        goto exit;
+    }
+
+    file_len = (unsigned int)st.st_size;
+    file_buffer = malloc(file_len + 1);
+    if (file_buffer == NULL) {
+        osfp_log_error("Not enough memory for file buffer. file name: '%s'\n",fp_file);
+        goto exit;
+    }
+
+    fp = fopen(fp_file, "r");
+    if (fp == NULL) {
+        osfp_log_error("Cannot open '%s' for reading.\n", fp_file);
+        goto exit;
+    }
+
+    ret = fread(file_buffer, 1, file_len, fp);
+    if (ret < 0) {
+        osfp_log_error("fread() failed on '%s'.\n", fp_file);
+        free(file_buffer);
+        fclose(fp);
+        goto exit;
+    }
+
+    fclose(fp);
+
+    file_buffer[file_len] = 0;
+
+    return file_buffer;
+exit:
+    return NULL;
+}
+
 int osfp_score_db_load(struct osfp_score_db *score_db, char *fp_file)
 {
     int ret = OSFP_EINVAL, i, count;