diff --git a/README.md b/README.md
index 97ac23f..a0f30be 100644
--- a/README.md
+++ b/README.md
@@ -21,6 +21,16 @@ It will place the goCaptcha box in the div:
 
 ### 1.2 - Backend
 - Put dataset images in the folder 'imgs'.
+- Configure serverConfig.json:
+```json
+{
+    "serverIP": "127.0.0.1",
+    "serverPort": "3025",
+    "imgsFolder": "imgs",
+    "numImgsCaptcha": 9
+}
+```
+
 - Run MongoDB.
 - Go to the folder /goCaptcha, and run:
 ```
@@ -183,3 +193,4 @@ If the selection is correct, returns 'true', if the selection is not correct, re
 - If the captcha is resolved in less than 1 second, it's not valid.
 - If the captcha is resolved in more than 1 minute, it's not valid.
 - The images url, are UUIDs generated each time, in order to give different names for the images each time.
+- The ip of requested captcha and answered captcha petitions must be the same.
diff --git a/captcha.go b/captcha.go
index bdbf31b..308251a 100644
--- a/captcha.go
+++ b/captcha.go
@@ -21,6 +21,7 @@ type CaptchaSol struct {
 	ImgsSolution []string `json:"imgssolution"`
 	Question     string   `json:"question"` //select all X
 	Date         int64    `json:"date"`
+	Ip           string   `json:"ip"`
 }
 type CaptchaAnswer struct {
 	CaptchaId string `json:"captchaid"`
@@ -47,7 +48,7 @@ func generateQuestionFromCategoriesArray(imgs []string) string {
 	n := generateRandInt(0, len(imgs))
 	return imgs[n]
 }
-func generateCaptcha(count int) Captcha {
+func generateCaptcha(count int, ip string) Captcha {
 	var captcha Captcha
 	var captchaSol CaptchaSol
 
@@ -71,11 +72,12 @@ func generateCaptcha(count int) Captcha {
 	captcha.Question = question
 	captchaSol.Question = question
 	captchaSol.Date = time.Now().Unix()
+	captchaSol.Ip = ip
 	err := captchaSolCollection.Insert(captchaSol)
 	check(err)
 	return captcha
 }
-func validateCaptcha(captchaAnswer CaptchaAnswer) bool {
+func validateCaptcha(captchaAnswer CaptchaAnswer, ip string) bool {
 	var solved bool
 	solved = true
 	captchaSol := CaptchaSol{}
@@ -108,5 +110,9 @@ func validateCaptcha(captchaAnswer CaptchaAnswer) bool {
 	if elapsed.Seconds() > 60 {
 		solved = false
 	}
+	//ip comprovation
+	if captchaSol.Ip != ip {
+		solved = false
+	}
 	return solved
 }
diff --git a/goCaptcha b/goCaptcha
index 6d436d8..ecc4a74 100755
Binary files a/goCaptcha and b/goCaptcha differ
diff --git a/serverConfig.go b/serverConfig.go
index 2d56dac..e45e688 100644
--- a/serverConfig.go
+++ b/serverConfig.go
@@ -20,9 +20,10 @@ type Route struct {
 
 //server config
 type ServerConfig struct {
-	ServerIP   string `json:"serverIP"`
-	ServerPort string `json:"serverPort"`
-	ImgsFolder string `json:"imgsFolder"`
+	ServerIP       string `json:"serverIP"`
+	ServerPort     string `json:"serverPort"`
+	ImgsFolder     string `json:"imgsFolder"`
+	NumImgsCaptcha int    `json:"numImgsCaptcha"`
 }
 
 var serverConfig ServerConfig
diff --git a/serverConfig.json b/serverConfig.json
index d3f940b..b12ab8f 100644
--- a/serverConfig.json
+++ b/serverConfig.json
@@ -1,5 +1,6 @@
 {
     "serverIP": "127.0.0.1",
     "serverPort": "3025",
-    "imgsFolder": "imgs"
+    "imgsFolder": "imgs",
+    "numImgsCaptcha": 9
 }
diff --git a/serverRoutes.go b/serverRoutes.go
index 2b58377..d1e77b7 100644
--- a/serverRoutes.go
+++ b/serverRoutes.go
@@ -56,8 +56,6 @@ func GetImage(w http.ResponseWriter, r *http.Request) {
 	err := imgFakePathCollection.Find(bson.M{"fake": imageName}).One(&imgFakePath)
 	check(err)
 
-	fmt.Println(serverConfig.ImgsFolder + "/" + imgFakePath.Real)
-
 	file, err := ioutil.ReadFile(serverConfig.ImgsFolder + "/" + imgFakePath.Real)
 	if err != nil {
 		fmt.Fprintln(w, err)
@@ -75,7 +73,8 @@ func GetImage(w http.ResponseWriter, r *http.Request) {
 }
 func GetCaptcha(w http.ResponseWriter, r *http.Request) {
 
-	resp := generateCaptcha(6)
+	ip := strings.Split(r.RemoteAddr, ":")[0]
+	resp := generateCaptcha(serverConfig.NumImgsCaptcha, ip)
 	jsonResp, err := json.Marshal(resp)
 	check(err)
 	fmt.Fprintln(w, string(jsonResp))
@@ -88,7 +87,8 @@ func AnswerCaptcha(w http.ResponseWriter, r *http.Request) {
 	check(err)
 	defer r.Body.Close()
 
-	resp := validateCaptcha(captchaAnswer)
+	ip := strings.Split(r.RemoteAddr, ":")[0]
+	resp := validateCaptcha(captchaAnswer, ip)
 	jsonResp, err := json.Marshal(resp)
 	check(err)
 	fmt.Fprintln(w, string(jsonResp))
diff --git a/web/goCaptcha.js b/web/goCaptcha.js
index cfd389c..c96d224 100644
--- a/web/goCaptcha.js
+++ b/web/goCaptcha.js
@@ -1,5 +1,5 @@
 
-var selection = [0, 0, 0, 0, 0, 0];
+var selection = [];
 var captchaid = "";
 
 function httpGet(url) {
@@ -22,6 +22,10 @@ function getCaptcha() {
     captcha = JSON.parse(data);
     captchaid = captcha.id;
     showCaptcha(captcha);
+    selection=[];
+    for(k in captcha.imgs){
+        selection.push(0);
+    }
 }
 
 function showCaptcha(captcha) {
@@ -56,7 +60,6 @@ function validateCaptcha() {
     if (resp) {
         html += "<h2>goCaptcha validated</h2>";
     } else {
-        selection = [0, 0, 0, 0, 0, 0];
         html += "<h2>goCaptcha failed</h2>";
         html += "<div onclick='getCaptcha()' class='g_button c_red300 g_floatRight'>Reload Captcha</div>";
     }