diff --git a/E5Renewer.Tests/Models/UintExtendsTests.cs b/E5Renewer.Tests/Models/UintExtendsTests.cs
new file mode 100644
index 0000000..706df8f
--- /dev/null
+++ b/E5Renewer.Tests/Models/UintExtendsTests.cs
@@ -0,0 +1,43 @@
+using E5Renewer.Models;
+
+namespace E5Renewer.Tests.Models;
+
+/// <summary>Test
+/// <see cref="UintExtends"/>
+/// </summary>
+[TestClass]
+public class UintExtendsTests
+{
+    /// <summary>
+    /// Test
+    /// <see cref="UintExtends.ToUnixFileMode(uint)" />
+    /// </summary>
+    [TestMethod]
+    [DataRow(0b000000000, UnixFileMode.None)]
+    [DataRow(0b000000001, UnixFileMode.OtherExecute)]
+    [DataRow(0b000000010, UnixFileMode.OtherWrite)]
+    [DataRow(0b000000011, UnixFileMode.OtherWrite | UnixFileMode.OtherExecute)]
+    [DataRow(0b000000100, UnixFileMode.OtherRead)]
+    [DataRow(0b000000101, UnixFileMode.OtherRead | UnixFileMode.OtherExecute)]
+    [DataRow(0b000000110, UnixFileMode.OtherRead | UnixFileMode.OtherWrite)]
+    [DataRow(0b000000111, UnixFileMode.OtherRead | UnixFileMode.OtherWrite | UnixFileMode.OtherExecute)]
+    [DataRow(0b000001000, UnixFileMode.GroupExecute)]
+    [DataRow(0b000010000, UnixFileMode.GroupWrite)]
+    [DataRow(0b000011000, UnixFileMode.GroupWrite | UnixFileMode.GroupExecute)]
+    [DataRow(0b000100000, UnixFileMode.GroupRead)]
+    [DataRow(0b000101000, UnixFileMode.GroupRead | UnixFileMode.GroupExecute)]
+    [DataRow(0b000110000, UnixFileMode.GroupRead | UnixFileMode.GroupWrite)]
+    [DataRow(0b000111000, UnixFileMode.GroupRead | UnixFileMode.GroupWrite | UnixFileMode.GroupExecute)]
+    [DataRow(0b001000000, UnixFileMode.UserExecute)]
+    [DataRow(0b010000000, UnixFileMode.UserWrite)]
+    [DataRow(0b011000000, UnixFileMode.UserWrite | UnixFileMode.UserExecute)]
+    [DataRow(0b100000000, UnixFileMode.UserRead)]
+    [DataRow(0b101000000, UnixFileMode.UserRead | UnixFileMode.UserExecute)]
+    [DataRow(0b110000000, UnixFileMode.UserRead | UnixFileMode.UserWrite)]
+    [DataRow(0b111000000, UnixFileMode.UserRead | UnixFileMode.UserWrite | UnixFileMode.UserExecute)]
+    [DataRow(0b100100100, UnixFileMode.UserRead | UnixFileMode.GroupRead | UnixFileMode.OtherRead)]
+    public void TestToUnixFileMode(int permission, UnixFileMode mode)
+    {
+        Assert.AreEqual(mode, ((uint)permission).ToUnixFileMode());
+    }
+}
diff --git a/E5Renewer/Models/Config/Config.cs b/E5Renewer/Models/Config/Config.cs
index 2d093a7..bafce6c 100644
--- a/E5Renewer/Models/Config/Config.cs
+++ b/E5Renewer/Models/Config/Config.cs
@@ -56,7 +56,7 @@ public Config()
             this.listenAddr = "127.0.0.1";
             this.listenPort = 8888;
             this.listenSocket = "/run/e5renewer/e5renewer.socket";
-            this.listenSocketPermission = 666;
+            this.listenSocketPermission = Convert.ToUInt32("666", 8);
             this.users = new();
         }
     }
diff --git a/E5Renewer/Models/UintExtends.cs b/E5Renewer/Models/UintExtends.cs
index 3f2497c..0d5f714 100644
--- a/E5Renewer/Models/UintExtends.cs
+++ b/E5Renewer/Models/UintExtends.cs
@@ -5,6 +5,9 @@ namespace E5Renewer.Models
     /// </summary>
     public static class UintExtends
     {
+        private const uint minPermission = 0; // 0o000
+        private const uint maxPermission = 511; // 0o777
+
         /// <summary>Convert
         /// <see cref="uint">uint</see>
         /// to
@@ -12,50 +15,18 @@ public static class UintExtends
         /// </summary>
         public static UnixFileMode ToUnixFileMode(this uint permission)
         {
-            if (permission > 777)
+
+            if (permission < UintExtends.minPermission)
             {
-                permission = 777;
+                permission = UintExtends.minPermission;
             }
-            uint user = permission / 100;
-            uint group = (permission - user * 100) / 10;
-            uint other = permission - user * 100 - group * 10;
-            UnixFileMode userFileMode = user switch
+
+            if (permission > UintExtends.maxPermission)
             {
-                0 => UnixFileMode.None,
-                1 => UnixFileMode.UserExecute,
-                2 => UnixFileMode.UserWrite,
-                3 => UnixFileMode.UserWrite | UnixFileMode.UserExecute,
-                4 => UnixFileMode.UserRead,
-                5 => UnixFileMode.UserRead | UnixFileMode.UserExecute,
-                6 => UnixFileMode.UserRead | UnixFileMode.UserWrite,
-                7 => UnixFileMode.UserRead | UnixFileMode.UserWrite | UnixFileMode.UserExecute,
-                _ => throw new ArgumentOutOfRangeException(nameof(user), string.Format("Invalid unix user permission value {0}", user))
-            };
-            UnixFileMode groupFileMode = group switch
-            {
-                0 => UnixFileMode.None,
-                1 => UnixFileMode.GroupExecute,
-                2 => UnixFileMode.GroupWrite,
-                3 => UnixFileMode.GroupWrite | UnixFileMode.GroupExecute,
-                4 => UnixFileMode.GroupRead,
-                5 => UnixFileMode.GroupRead | UnixFileMode.GroupExecute,
-                6 => UnixFileMode.GroupRead | UnixFileMode.GroupWrite,
-                7 => UnixFileMode.GroupRead | UnixFileMode.GroupWrite | UnixFileMode.GroupExecute,
-                _ => throw new ArgumentOutOfRangeException(nameof(group), string.Format("Invalid unix group permission value {0}", group))
-            };
-            UnixFileMode otherFileMode = other switch
-            {
-                0 => UnixFileMode.None,
-                1 => UnixFileMode.OtherExecute,
-                2 => UnixFileMode.OtherWrite,
-                3 => UnixFileMode.OtherWrite | UnixFileMode.OtherExecute,
-                4 => UnixFileMode.OtherRead,
-                5 => UnixFileMode.OtherRead | UnixFileMode.OtherExecute,
-                6 => UnixFileMode.OtherRead | UnixFileMode.OtherWrite,
-                7 => UnixFileMode.OtherRead | UnixFileMode.OtherWrite | UnixFileMode.OtherExecute,
-                _ => throw new ArgumentOutOfRangeException(nameof(other), string.Format("Invalid unix other permission {0}", other))
-            };
-            return userFileMode | groupFileMode | otherFileMode;
+                permission = UintExtends.maxPermission;
+            }
+
+            return (UnixFileMode)permission;
         }
     }
 }
diff --git a/README.md b/README.md
index ca15eeb..c7e5e0d 100644
--- a/README.md
+++ b/README.md
@@ -37,6 +37,10 @@ A tool to renew e5 subscription by calling msgraph APIs
     If you want to use certificate instead secret, which is better for security, you can write a `certificate` key with path to your certificate file instead `secret` key.
 
     Tips: We support json, yaml and toml formats, just let their contents be equal, the configuration result is same.
+    
+    > [!NOTE]
+    > Due to that C# does not have a native octal number support, we use the `listen_socket_permission` as unix permission directly.
+    > For example, if you are using json format, you need to set it to `438` in order to see socket mode is `rw-rw-rw-`.
 
 3. Install .NET