diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index e9aa82d..c81a59f 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -2,6 +2,7 @@
 <project version="4">
   <component name="ChangeListManager">
     <list default="true" id="42982c84-cdb2-4596-b4aa-818c31fc199a" name="Default" comment="">
+      <change type="MODIFICATION" beforePath="$PROJECT_DIR$/README.md" afterPath="$PROJECT_DIR$/README.md" />
       <change type="MODIFICATION" beforePath="$PROJECT_DIR$/src/main/java/security.java" afterPath="$PROJECT_DIR$/src/main/java/security.java" />
       <change type="MODIFICATION" beforePath="$PROJECT_DIR$/src/main/java/test.java" afterPath="$PROJECT_DIR$/src/main/java/test.java" />
     </list>
@@ -29,12 +30,12 @@
           </provider>
         </entry>
       </file>
-      <file leaf-file-name="README.md" pinned="false" current-in-tab="false">
+      <file leaf-file-name="README.md" pinned="false" current-in-tab="true">
         <entry file="file://$PROJECT_DIR$/README.md">
           <provider selected="true" editor-type-id="split-provider[text-editor;markdown-preview-editor]">
             <state split_layout="SPLIT">
-              <first_editor relative-caret-position="238">
-                <caret line="14" column="3" lean-forward="true" selection-start-line="14" selection-start-column="3" selection-end-line="14" selection-end-column="3" />
+              <first_editor relative-caret-position="37">
+                <caret line="29" column="14" lean-forward="true" selection-start-line="29" selection-start-column="14" selection-end-line="29" selection-end-column="14" />
                 <folding />
               </first_editor>
               <second_editor />
@@ -42,11 +43,11 @@
           </provider>
         </entry>
       </file>
-      <file leaf-file-name="security.java" pinned="false" current-in-tab="true">
+      <file leaf-file-name="security.java" pinned="false" current-in-tab="false">
         <entry file="file://$PROJECT_DIR$/src/main/java/security.java">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="276">
-              <caret line="66" column="59" lean-forward="false" selection-start-line="66" selection-start-column="59" selection-end-line="66" selection-end-column="59" />
+            <state relative-caret-position="206">
+              <caret line="18" column="14" lean-forward="true" selection-start-line="18" selection-start-column="14" selection-end-line="18" selection-end-column="38" />
               <folding>
                 <element signature="n#!!doc" expanded="true" />
                 <element signature="imports" expanded="true" />
@@ -58,8 +59,8 @@
       <file leaf-file-name="test.java" pinned="false" current-in-tab="false">
         <entry file="file://$PROJECT_DIR$/src/main/java/test.java">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="289">
-              <caret line="17" column="50" lean-forward="false" selection-start-line="17" selection-start-column="50" selection-end-line="17" selection-end-column="50" />
+            <state relative-caret-position="220">
+              <caret line="13" column="32" lean-forward="true" selection-start-line="13" selection-start-column="32" selection-end-line="13" selection-end-column="32" />
               <folding />
             </state>
           </provider>
@@ -87,9 +88,9 @@
       <list>
         <option value="$PROJECT_DIR$/pom.xml" />
         <option value="$PROJECT_DIR$/src/main/java/main.java" />
-        <option value="$PROJECT_DIR$/README.md" />
-        <option value="$PROJECT_DIR$/src/main/java/test.java" />
         <option value="$PROJECT_DIR$/src/main/java/security.java" />
+        <option value="$PROJECT_DIR$/src/main/java/test.java" />
+        <option value="$PROJECT_DIR$/README.md" />
       </list>
     </option>
   </component>
@@ -657,12 +658,12 @@
       <option name="number" value="Default" />
       <option name="presentableId" value="Default" />
       <updated>1504604417100</updated>
-      <workItem from="1504604422158" duration="3470000" />
+      <workItem from="1504604422158" duration="4673000" />
     </task>
     <servers />
   </component>
   <component name="TimeTrackingManager">
-    <option name="totallyTimeSpent" value="3470000" />
+    <option name="totallyTimeSpent" value="4673000" />
   </component>
   <component name="ToolWindowManager">
     <frame x="0" y="0" width="1280" height="800" extended-state="0" />
@@ -677,7 +678,7 @@
       <window_info id="Capture Analysis" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
       <window_info id="Event Log" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="true" content_ui="tabs" />
       <window_info id="Maven Projects" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
-      <window_info id="Run" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="true" show_stripe_button="true" weight="0.32876712" sideWeight="0.5" order="2" side_tool="false" content_ui="tabs" />
+      <window_info id="Run" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="true" show_stripe_button="true" weight="0.33424658" sideWeight="0.5" order="2" side_tool="false" content_ui="tabs" />
       <window_info id="Version Control" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
       <window_info id="Properties" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
       <window_info id="Terminal" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
@@ -763,29 +764,18 @@
         </state>
       </provider>
     </entry>
-    <entry file="file://$PROJECT_DIR$/README.md">
-      <provider selected="true" editor-type-id="split-provider[text-editor;markdown-preview-editor]">
-        <state split_layout="SPLIT">
-          <first_editor relative-caret-position="238">
-            <caret line="14" column="3" lean-forward="true" selection-start-line="14" selection-start-column="3" selection-end-line="14" selection-end-column="3" />
-            <folding />
-          </first_editor>
-          <second_editor />
-        </state>
-      </provider>
-    </entry>
     <entry file="file://$PROJECT_DIR$/src/main/java/test.java">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="289">
-          <caret line="17" column="50" lean-forward="false" selection-start-line="17" selection-start-column="50" selection-end-line="17" selection-end-column="50" />
+        <state relative-caret-position="220">
+          <caret line="13" column="32" lean-forward="true" selection-start-line="13" selection-start-column="32" selection-end-line="13" selection-end-column="32" />
           <folding />
         </state>
       </provider>
     </entry>
     <entry file="file://$PROJECT_DIR$/src/main/java/security.java">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="276">
-          <caret line="66" column="59" lean-forward="false" selection-start-line="66" selection-start-column="59" selection-end-line="66" selection-end-column="59" />
+        <state relative-caret-position="206">
+          <caret line="18" column="14" lean-forward="true" selection-start-line="18" selection-start-column="14" selection-end-line="18" selection-end-column="38" />
           <folding>
             <element signature="n#!!doc" expanded="true" />
             <element signature="imports" expanded="true" />
@@ -793,5 +783,16 @@
         </state>
       </provider>
     </entry>
+    <entry file="file://$PROJECT_DIR$/README.md">
+      <provider selected="true" editor-type-id="split-provider[text-editor;markdown-preview-editor]">
+        <state split_layout="SPLIT">
+          <first_editor relative-caret-position="37">
+            <caret line="29" column="14" lean-forward="true" selection-start-line="29" selection-start-column="14" selection-end-line="29" selection-end-column="14" />
+            <folding />
+          </first_editor>
+          <second_editor />
+        </state>
+      </provider>
+    </entry>
   </component>
 </project>
\ No newline at end of file
diff --git a/README.md b/README.md
index 1768fd4..4373256 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,14 @@
 
 ## URL白名单验证
 
-验证代码
+### 验证逻辑
+
+1. 取URL一级域名
+2. 判断是否在域名白名单列表内
+
+### 验证代码
+
+合法URL返回true，非法URL返回false
 
 ```java
 security checkUrl = new security();
@@ -12,4 +19,26 @@ String[] urlWList = {"joychou.com", "joychou.me"};
 Boolean ret = checkUrl.checkUrlWlist("http://test.joychou.me", urlWList);
 System.out.println(ret);
 
-```
\ No newline at end of file
+```
+
+## SSRF
+
+JAVA默认dns请求会有30s的缓存，所以默认不存在dns rebind问题。除非重新设置ttl为0。
+### 验证逻辑
+
+1. 取URL的IP
+2. 判断IP是否是内网IP
+3. 判断是否是内网IP
+4. 请求URL
+5. 如果有跳转，取出跳转URL，执行1
+
+### 验证代码
+
+如果是内网IP，返回false，表示checkSSRF不通过。
+否则返回true。即合法返回true。
+URL只支持HTTP协议。
+
+```java
+ret = checkUrl.checkSSRF("http://127.0.0.1");
+System.out.println(ret);
+```
diff --git a/src/main/java/security.java b/src/main/java/security.java
index dd0883d..3204197 100644
--- a/src/main/java/security.java
+++ b/src/main/java/security.java
@@ -77,7 +77,7 @@ public class security {
                 // 判断当前请求的URL是否是内网ip
                 Boolean bRet = isInnerIpFromUrl(finalUrl);
                 if (bRet) {
-                    return true;
+                    return false;
                 }
 
                 connection = (HttpURLConnection) new URL(finalUrl).openConnection();
@@ -98,9 +98,9 @@ public class security {
             } while (connection.getResponseCode() != HttpURLConnection.HTTP_OK);
             connection.disconnect();
         } catch (Exception e) {
-            return false;
+            return true;
         }
-        return false;
+        return true;
     }
 
     /*
diff --git a/src/main/java/test.java b/src/main/java/test.java
index ba0e090..4f0284b 100644
--- a/src/main/java/test.java
+++ b/src/main/java/test.java
@@ -10,7 +10,7 @@ public class test {
         // URL白名单组件测试
         security checkUrl = new security();
         String[] urlWList = {"joychou.com", "joychou.me"};
-        Boolean ret = checkUrl.checkUrlWlist("http://test.joychou.me", urlWList);
+        Boolean ret = checkUrl.checkUrlWlist("http://test.joychou.org", urlWList);
         System.out.println(ret);
 
         // SSRF组件测试
diff --git a/target/classes/security.class b/target/classes/security.class
index a43fc1d..1206b8e 100644
Binary files a/target/classes/security.class and b/target/classes/security.class differ
diff --git a/target/classes/test.class b/target/classes/test.class
index 2de076d..de8c665 100644
Binary files a/target/classes/test.class and b/target/classes/test.class differ