diff --git a/Basis/Functions.py b/Basis/Functions.py
index b718065..923c439 100644
--- a/Basis/Functions.py
+++ b/Basis/Functions.py
@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
+import re
 import time
 import uuid
 import psutil
@@ -10,9 +11,28 @@ from IPy import IP
 from Basis.Logger import logging
 
 
-def isHost(raw) -> bool:
-    # TODO: isHost function
-    return True
+def isIpAddr(ipAddr: str) -> bool:
+    try:
+        if '/' in ipAddr:  # filter CIDR
+            return False
+        if '.' not in ipAddr and ':' not in ipAddr:  # not IPv4 or IPv6
+            return False
+        IP(ipAddr)  # try to convert to IP address
+        return True  # valid IP address
+    except:
+        return False
+
+
+def isDomain(domain: str) -> bool:
+    try:
+        domainRegex = r'^(?=^.{3,255}$)[a-zA-Z0-9_][a-zA-Z0-9_-]{0,62}(\.[a-zA-Z0-9_][a-zA-Z0-9_-]{0,62})+$'
+        return re.search(domainRegex, domain) is not None  # regex matching
+    except:  # unexpected error
+        return False
+
+
+def isHost(host: str) -> bool:
+    return isIpAddr(host) or isDomain(host)  # IPv4 / IPv6 / Domain
 
 
 def isPort(port: int) -> bool:
@@ -22,7 +42,7 @@ def isPort(port: int) -> bool:
 
 
 def md5Sum(data: str, encode: str = 'utf-8') -> str:
-    return hashlib.md5(data.encode(encoding = encode)).hexdigest()
+    return hashlib.md5(data.encode(encoding = encode)).hexdigest()  # MD5 hash
 
 
 def hostFormat(host: str, v6Bracket: bool = False) -> str:
diff --git a/Filter/Shadowsocks.py b/Filter/Shadowsocks.py
index 1053eee..7b23a54 100644
--- a/Filter/Shadowsocks.py
+++ b/Filter/Shadowsocks.py
@@ -10,7 +10,7 @@ from Basis.Functions import isHost, isPort
 ssObject = rulesFilter({
     'server': {
         'type': str,
-        'format': toStr,
+        'format': lambda s: toStr(s).strip().lower(),
         'filter': isHost,
         'errMsg': 'Invalid server address'
     },
diff --git a/Filter/ShadowsocksR.py b/Filter/ShadowsocksR.py
new file mode 100644
index 0000000..807ed26
--- /dev/null
+++ b/Filter/ShadowsocksR.py
@@ -0,0 +1,74 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+from Basis.Filter import rulesFilter
+from Basis.Functions import toInt, toStr
+from Basis.Functions import isHost, isPort
+from Basis.Constant import ssrMethods, ssrProtocols, ssrObfuscations
+
+
+def ssrProtocolFormat(protocol: str) -> str:
+    protocol = toStr(protocol).strip().lower().replace('-', '_')
+    return 'origin' if protocol == '' else protocol  # '' -> origin
+
+
+def ssrObfsFormat(obfs: str) -> str:
+    obfs = toStr(obfs).strip().lower().replace('-', '_')
+    return 'plain' if obfs == '' else obfs  # '' -> plain
+
+
+ssrObject = rulesFilter({
+    'server': {
+        'type': str,
+        'format': lambda s: toStr(s).strip().lower(),
+        '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 ssrMethods,
+        'errMsg': 'Unknown ShadowsocksR method'
+    },
+    'passwd': {
+        'type': str,
+        'format': toStr,
+        'errMsg': 'Invalid password content'
+    },
+    'protocol': {
+        'optional': True,
+        'default': 'origin',
+        'type': str,
+        'format': ssrProtocolFormat,
+        'filter': lambda s: s in ssrProtocols,
+        'errMsg': 'Unknown ShadowsocksR protocol'
+    },
+    'protocolParam': {
+        'optional': True,
+        'default': '',
+        'type': str,
+        'format': toStr,
+        'errMsg': 'Invalid ShadowsocksR protocol param'
+    },
+    'obfs': {
+        'optional': True,
+        'default': 'plain',
+        'type': str,
+        'format': ssrObfsFormat,
+        'filter': lambda s: s in ssrObfuscations,
+        'errMsg': 'Unknown ShadowsocksR obfuscation'
+    },
+    'obfsParam': {
+        'optional': True,
+        'default': '',
+        'type': str,
+        'format': toStr,
+        'errMsg': 'Invalid ShadowsocksR obfuscation param'
+    }
+})
diff --git a/demo.py b/demo.py
index ddaa726..360f70b 100755
--- a/demo.py
+++ b/demo.py
@@ -4,8 +4,10 @@ from pprint import pprint
 from Basis.Filter import Filter
 from Basis.Filter import filterObject
 from Filter.Shadowsocks import ssObject
+from Filter.ShadowsocksR import ssrObject
 
 # pprint(ssObject, sort_dicts = False)
+# pprint(ssrObject, sort_dicts = False)
 # pprint(filterObject, sort_dicts = False)
 
 ssProxy = {
@@ -14,9 +16,19 @@ ssProxy = {
     'method': 'none',
     'passwd': 'dnomd343',
     'plugin': {
-        'type': 'obfs',
-
+        'type': 'obfs'
     }
 }
-ret = Filter(ssProxy, ssObject)
+
+ssrProxy = {
+    'server': '1.1.1.1',
+    'port': 12345,
+    'method': 'table',
+    'passwd': 'dnomd343',
+    'protocol': 'auth_chain-a',
+    'obfs': 'http_post'
+}
+
+# ret = Filter(ssProxy, ssObject)
+ret = Filter(ssrProxy, ssrObject)
 pprint(ret, sort_dicts = False)