diff --git a/Basis/Functions.py b/Basis/Functions.py
index ffb0565..544de97 100644
--- a/Basis/Functions.py
+++ b/Basis/Functions.py
@@ -86,3 +86,23 @@ def networkStatus() -> list:  # get all network connections
         })
     logging.debug('Network status -> found %i connections' % len(result))
     return result
+
+
+def toInt(raw) -> int:
+    pass
+
+
+def toStr(raw) -> str:
+    pass
+
+
+def toBool(raw) -> bool:
+    pass
+
+
+def isHost(raw) -> bool:
+    pass
+
+
+def isPort(raw) -> bool:
+    pass
diff --git a/Filter/Plugin.py b/Filter/Plugin.py
new file mode 100644
index 0000000..2b98da0
--- /dev/null
+++ b/Filter/Plugin.py
@@ -0,0 +1,5 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+def pluginFormat(pluginName: str) -> str:
+    return pluginName
diff --git a/Filter/Shadowsocks.py b/Filter/Shadowsocks.py
new file mode 100644
index 0000000..9702174
--- /dev/null
+++ b/Filter/Shadowsocks.py
@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+from Filter.Plugin import pluginFormat
+from Basis.Functions import toInt, toStr
+from Basis.Functions import isHost, isPort
+from Basis.Constant import ssMethods, pluginClients
+
+pluginObject = {
+    'type': {
+        'type': str,
+        'format': lambda s: pluginFormat(toStr(s).strip().lower()),
+        'filter': lambda s: s in pluginClients,
+        'errMsg': 'Unknown SIP003 plugin'
+    },
+    'param': {
+        'optional': False,
+        'default': '',
+        'type': str,
+        'format': toStr,
+        'errMsg': 'Invalid SIP003 param'
+    }
+}
+
+ssObject = {
+    'server': {
+        'type': str,
+        'format': toStr,
+        'filter': isHost,
+        'errMsg': 'Invalid server address'
+    },
+    'port': {
+        'type': int,
+        'format': toInt,
+        'filter': isPort,
+        'errMsg': 'Invalid port number'
+    },
+    'method': {
+        'type': str,
+        'format': lambda s: toStr(s).strip().lower().replace('_', '-'),
+        'filter': lambda s: s in ssMethods,
+        'errMsg': 'Unknown Shadowsocks method'
+    },
+    'passwd': {
+        'type': str,
+        'format': toStr,
+        'errMsg': 'Invalid password content'
+    },
+    'plugin': {
+        'optional': False,
+        'default': None,
+        'allowNone': True,
+        'type': pluginObject,
+        'errMsg': 'Invalid pluginObject'
+    }
+}
diff --git a/Filter/__init__.py b/Filter/__init__.py
new file mode 100644
index 0000000..50635e4
--- /dev/null
+++ b/Filter/__init__.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+"""
+xxObject = {  # a dict that describe multi-field
+    'field_1': {
+        'optional': ...,  # field force require or not
+        'default': ...,  # default value when field is not exist (optional == True)
+        'allowNone': ...,  # whether the value can be None (override the format and filter process)
+        'type': ...,  # type of field content (in filter process) (python type / dict)
+        'multiSub': ...,  # whether there are multi subObject (type is dict)
+        'indexKey': ...,  # index key of subObject (type is dict and multiSub == True)
+        'format': ...,  # format function (before filter process) (invalid content -> throw error)
+        'filter': ...,  # filter function -> bool (throw error when return False)
+        'errMsg': ...,  # raise message if there is something error
+    },
+    'field_2': {
+        ...
+    },
+    ...
+}
+
+
+default value
+  + optional: False
+  + default: None
+  + allowNone: False
+  + format: lambda -> return same thing
+  + type: force require
+  + multiSub: False
+  + indexKey: 'type'
+  + filter: lambda -> return True
+  + errMsg: 'filter error'
+
+
+pre process
+  => field not exist
+    => optional == False -> throw errMsg
+    => optional == True -> set as default value -> continue
+  => field exist
+    => filed is None
+      => allowNone is False -> throw errMsg
+      => allowNone is True -> break
+    => field is not None -> continue
+
+format process -> set as field value (maybe throw error -> catch and throw errMsg)
+
+filter process
+  => type is `python type` -> compare with field type -> filter function check
+  => type is dict
+    => multiSub == False -> recursive check
+    => multiSub == True
+      => field content is not dict or not include indexKey -> throw error
+      => others
+        => indexKey's content not in type (dict) -> throw error
+        => others -> recursive check
+
+"""