diff --git a/common.h b/common.h
index b6c559f..130c3e2 100644
--- a/common.h
+++ b/common.h
@@ -163,6 +163,8 @@ extern int force_socket_buf;
 
 extern int g_fix_gro;
 
+extern int g_tcp_spa;
+
 /*
 struct ip_port_t
 {
diff --git a/git_version.h b/git_version.h
new file mode 100644
index 0000000..dc89f81
--- /dev/null
+++ b/git_version.h
@@ -0,0 +1 @@
+const char *gitversion = "e42f0e573221c5e0146c02fd5d71f32aa93c7221";
diff --git a/misc.cpp b/misc.cpp
index 737c9be..bdb9645 100644
--- a/misc.cpp
+++ b/misc.cpp
@@ -148,7 +148,9 @@ void print_help() {
     printf("    --disable-anti-replay                 disable anti-replay,not suggested\n");
     printf("    --fix-gro                             try to fix huge packet caused by GRO. this option is at an early stage.\n");
     printf("                                          make sure client and server are at same version.\n");
-
+    printf("    --tcp-spa                             TCP SPA mode to avoid port scanning.\n");
+    printf("                                          when enable on server mode, will check SYN's option.\n");
+    
     // printf("\n");
     printf("client options:\n");
     printf("    --source-ip           <ip>            force source-ip for raw socket\n");
@@ -296,6 +298,7 @@ void process_arg(int argc, char *argv[])  // process all options
             {"no-pcap-mutex", no_argument, 0, 1},
 #endif
             {"fix-gro", no_argument, 0, 1},
+            {"tcp-spa", no_argument, 0, 1},
             {NULL, 0, 0, 0}};
 
     process_log_level(argc, argv);
@@ -677,6 +680,9 @@ void process_arg(int argc, char *argv[])  // process all options
                 } else if (strcmp(long_options[option_index].name, "fix-gro") == 0) {
                     mylog(log_info, "--fix-gro enabled\n");
                     g_fix_gro = 1;
+                } else if (strcmp(long_options[option_index].name, "tcp-spa") == 0) {
+                    mylog(log_info, "--tcp-spa enabled\n");
+                    g_tcp_spa = 1;
                 } else {
                     mylog(log_warn, "ignored unknown long option ,option_index:%d code:<%x>\n", option_index, optopt);
                 }
diff --git a/network.cpp b/network.cpp
index bd01964..b878791 100644
--- a/network.cpp
+++ b/network.cpp
@@ -259,6 +259,40 @@ tcpdump -i eth1  ip and icmp -dd
  */
 #endif
 
+//tcp option for SPA
+int g_tcp_spa = 0;
+typedef struct tcpopt_data {
+    __u8 opcode;
+    __u8 opsize;
+    __u16 reserve;
+    __u32 csum;
+}tcpopt_data_t;
+
+#define TCPOPT_SPA      233  
+
+#define HASH_PRIME 16777619
+#define HASH_OFFSET 2166136261U
+
+//FNV-1a from GPT
+uint32_t checksum(uint32_t timestamp, const char* key) {
+    uint32_t hash = HASH_OFFSET;
+    const char* ptr = key;
+    size_t key_len = strlen(key);
+    
+    for (size_t i = 0; i < key_len; i++) {
+        hash ^= (uint32_t)ptr[i];
+        hash *= HASH_PRIME;
+    }
+
+    for (uint32_t i = 0; i < sizeof(uint32_t); i++) {
+        hash ^= (uint32_t)(timestamp & 0xFF);
+        hash *= HASH_PRIME;
+        timestamp >>= 8;
+    }
+    return hash;
+}
+//--------------
+
 packet_info_t::packet_info_t() {
     src_port = 0;
     dst_port = 0;
@@ -1679,6 +1713,16 @@ int send_raw_tcp(raw_info_t &raw_info, const char *payload, int payloadlen) {  /
         send_raw_tcp_buf[i++] = 0x03;
         send_raw_tcp_buf[i++] = 0x03;
         send_raw_tcp_buf[i++] = wscale;
+
+        if(g_tcp_spa && tcph->ack == 0) {
+            tcph->doff = 12;
+            tcpopt_data_t opt = {TCPOPT_SPA, sizeof(tcpopt_data_t), 0, 0};
+            uint32_t csum = checksum(ts, key_string);
+            opt.csum = htonl(csum);
+            memcpy(&send_raw_tcp_buf[i], &opt, opt.opsize);
+            i += opt.opsize;
+        }
+
     } else {
         tcph->doff = 8;
         int i = sizeof(my_tcphdr);
@@ -2113,6 +2157,8 @@ int parse_tcp_option(char *option_begin, char *option_end, packet_info_t &recv_i
     recv_info.has_ts = 0;
     recv_info.ts = 0;
 
+    tcpopt_data_t *opt = NULL;
+
     char *ptr = option_begin;
     // char *option_end=tcp_begin+tcp_hdr_len;
     while (ptr < option_end) {
@@ -2143,6 +2189,14 @@ int parse_tcp_option(char *option_begin, char *option_end, packet_info_t &recv_i
 
             // return 0;//we currently only parse ts, so just return after its found
             ptr += 10;
+        } else if (recv_info.syn == 1 && recv_info.ack == 0
+                && g_tcp_spa && (unsigned char)*ptr == TCPOPT_SPA) {
+            if (ptr + sizeof(tcpopt_data_t) > option_end) {
+                mylog(log_trace, "ptr+8>option_end for TCPOPT_SPA\n");
+                return -2;
+            }
+            opt = (tcpopt_data_t*)ptr;
+            ptr += sizeof(tcpopt_data_t);
         } else {
             if (ptr + 1 >= option_end) {
                 mylog(log_trace, "invaild option ptr+1==option_end\n");
@@ -2160,7 +2214,18 @@ int parse_tcp_option(char *option_begin, char *option_end, packet_info_t &recv_i
         // printf("!");
     }
     // printf("\n");
+    if(recv_info.syn == 1 && recv_info.ack == 0 && g_tcp_spa) {
+        if(opt == NULL) {
+            mylog(log_trace, "No found spa opt, pkt drop\n");
+            return -2;
+        }
 
+        uint32_t csum = checksum(htonl(recv_info.ts), key_string);
+        if(opt->csum != htonl(csum)){
+            mylog(log_trace, "SPA csum match failed\n");
+            return -2;
+        }
+    }
     return 0;
 }
 int recv_raw_tcp(raw_info_t &raw_info, char *&payload, int &payloadlen) {
@@ -2294,7 +2359,8 @@ int recv_raw_tcp(raw_info_t &raw_info, char *&payload, int &payloadlen) {
     }
     printf("<%d %d>\n",recv_info.ts,recv_info.ts_ack);
     */
-    parse_tcp_option(tcp_option, option_end, recv_info);
+
+    //parse_tcp_option(tcp_option, option_end, recv_info);
 
     recv_info.ack = tcph->ack;
     recv_info.syn = tcph->syn;
@@ -2304,6 +2370,9 @@ int recv_raw_tcp(raw_info_t &raw_info, char *&payload, int &payloadlen) {
 
     recv_info.seq = ntohl(tcph->seq);
 
+    if(-2 == parse_tcp_option(tcp_option, option_end, recv_info))
+        return -1;
+
     // recv_info.last_last_ack_seq=recv_info.last_ack_seq;
     // recv_info.last_ack_seq=recv_info.ack_seq;
     u32_t last_ack_seq = recv_info.ack_seq;
diff --git a/udp2raw b/udp2raw
new file mode 100755
index 0000000..e50b178
Binary files /dev/null and b/udp2raw differ