diff --git a/internal/check/ExternalMigration.go b/internal/check/ExternalMigration.go
index 76869e7..dcf4778 100644
--- a/internal/check/ExternalMigration.go
+++ b/internal/check/ExternalMigration.go
@@ -71,7 +71,7 @@ func genExternalMigrationSessionID(reqData dataType.UserRequest, ruleSet config.
 	return []byte(fmt.Sprintf("%s:%s", fmt.Sprintf("%d", time.Now().Unix()), fmt.Sprintf("%x", mac.Sum(nil))))
 }
 
-func verifyExternalMigrationSessionIDCookie(reqData dataType.UserRequest, ruleSet config.RuleSet) bool {
+func VerifyExternalMigrationSessionIDCookie(reqData dataType.UserRequest, ruleSet config.RuleSet) bool {
 	if reqData.ToriiSessionID == "" {
 		return false
 	}
@@ -95,3 +95,9 @@ func verifyExternalMigrationSessionIDCookie(reqData dataType.UserRequest, ruleSe
 	return hmac.Equal([]byte(computedHash), []byte(expectedHash))
 
 }
+
+func CalculateExternalMigrationHMAC(sessionID, timestampStr, secretKey string) string {
+	mac := hmac.New(sha512.New, []byte(secretKey))
+	mac.Write([]byte(fmt.Sprintf("%s%s", sessionID, timestampStr)))
+	return fmt.Sprintf("%x", mac.Sum(nil))
+}
diff --git a/internal/server/checker.go b/internal/server/checker.go
index 6e6ba2f..2fc8a17 100644
--- a/internal/server/checker.go
+++ b/internal/server/checker.go
@@ -109,7 +109,7 @@ func CheckMain(w http.ResponseWriter, userRequestData dataType.UserRequest, rule
 
 	} else if bytes.Compare(decision.HTTPCode, []byte("EXTERNAL")) == 0 {
 		w.Header().Set("Set-Cookie", "__torii_sessionid="+string(decision.ResponseData)+"; Path=/;  Max-Age=86400; Priority=High; HttpOnly; SameSite=Lax")
-		w.Header().Set("Location", ruleSet.ExternalMigrationRule.RedirectUrl+"?domain="+userRequestData.Host+"&session_id="+string(decision.ResponseData)+"&original_url="+userRequestData.Uri)
+		w.Header().Set("Location", ruleSet.ExternalMigrationRule.RedirectUrl+"?domain="+userRequestData.Host+"&session_id="+string(decision.ResponseData)+"&original_uri="+userRequestData.Uri)
 		w.WriteHeader(http.StatusFound)
 		return
 	} else {
diff --git a/internal/server/torii.go b/internal/server/torii.go
index 830b8fa..e888b89 100644
--- a/internal/server/torii.go
+++ b/internal/server/torii.go
@@ -2,6 +2,7 @@ package server
 
 import (
 	"bytes"
+	"crypto/hmac"
 	"html/template"
 	"net/http"
 	"server_torii/internal/action"
@@ -9,6 +10,7 @@ import (
 	"server_torii/internal/config"
 	"server_torii/internal/dataType"
 	"server_torii/internal/utils"
+	"strconv"
 	"time"
 )
 
@@ -20,6 +22,8 @@ func CheckTorii(w http.ResponseWriter, r *http.Request, reqData dataType.UserReq
 		check.CheckCaptcha(r, reqData, ruleSet, decision)
 	} else if reqData.Uri == cfg.WebPath+"/health_check" {
 		decision.SetResponse(action.Done, []byte("200"), []byte("ok"))
+	} else if reqData.Uri == cfg.WebPath+"/external_migration" {
+		handleExternalMigration(w, r, reqData, ruleSet, decision)
 	}
 	if bytes.Compare(decision.HTTPCode, []byte("200")) == 0 {
 		if bytes.Compare(decision.ResponseData, []byte("ok")) == 0 {
@@ -88,3 +92,44 @@ func CheckTorii(w http.ResponseWriter, r *http.Request, reqData dataType.UserReq
 		}
 	}
 }
+
+func handleExternalMigration(w http.ResponseWriter, r *http.Request, data dataType.UserRequest, set *config.RuleSet, decision *action.Decision) {
+	if !set.ExternalMigrationRule.Enabled {
+		decision.SetResponse(action.Done, []byte("200"), []byte("bad"))
+		return
+	}
+
+	originalURI := r.URL.Query().Get("original_uri")
+	timestampStr := r.URL.Query().Get("timestamp")
+	hmacParam := r.URL.Query().Get("hmac")
+
+	if timestampStr == "" || hmacParam == "" {
+		decision.SetResponse(action.Done, []byte("200"), []byte("bad"))
+		return
+	}
+
+	timestamp, err := strconv.ParseInt(timestampStr, 10, 64)
+	if err != nil {
+		decision.SetResponse(action.Done, []byte("200"), []byte("bad"))
+		return
+	}
+
+	currentTime := time.Now().Unix()
+	if currentTime-timestamp > set.ExternalMigrationRule.SessionTimeout {
+		decision.SetResponse(action.Done, []byte("200"), []byte("bad"))
+		return
+	}
+
+	if !check.VerifyExternalMigrationSessionIDCookie(data, *set) {
+		decision.SetResponse(action.Done, []byte("200"), []byte("badSession"))
+		return
+	}
+
+	expectedHMAC := check.CalculateExternalMigrationHMAC(data.ToriiSessionID, timestampStr, set.ExternalMigrationRule.SecretKey)
+	if !hmac.Equal([]byte(expectedHMAC), []byte(hmacParam)) {
+		decision.SetResponse(action.Done, []byte("200"), []byte("bad"))
+		return
+	}
+
+	decision.SetResponse(action.Continue, []byte("302"), []byte(originalURI))
+}