diff --git a/src/server.py b/src/server.py
--- a/src/server.py
+++ b/src/server.py
@@ -9,10 +9,10 @@ import config as conf
 
 class Connection:
 	def __init__(self,serverSocket):
-		self.socket, address = serverSocket.accept()
+		self._socket, address = serverSocket.accept()
 		log.info('Connected by {0}'.format(address))
-		fr=self.socket.makefile(mode="rb")
-		fw=self.socket.makefile(mode="wb")
+		fr=self._socket.makefile(mode="rb")
+		fw=self._socket.makefile(mode="wb")
 
 		self.incoming=NetworkReader(fr)
 		self.outcoming=NetworkWriter(fw)
@@ -21,32 +21,32 @@ class Connection:
 		return self.incoming,self.outcoming
 
 	def __exit__(self, exc_type, exc_val, exc_tb):
-		self.socket.close()
+		self._socket.close()
 
 
 class Server:
 	def __init__(self,filename,treeFile=""):
-		self.filename=filename
+		self._filename=filename
 		self._treeFile=treeFile
 
 		if treeFile:
-			self.tree=HashTree.load(treeFile)
+			self._tree=HashTree.load(treeFile)
 		else:
-			self.tree=HashTree.fromFile(filename)
+			self._tree=HashTree.fromFile(filename)
 
 		self._newLeaves=dict()
-		self.BLOCK_SIZE=self.tree.BLOCK_SIZE
+		self.BLOCK_SIZE=self._tree.BLOCK_SIZE
 
-		self.ss = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-		self.ss.bind(("",conf.port))
-		self.ss.listen(1)
+		self._ss = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+		self._ss.bind(("", conf.port))
+		self._ss.listen(1)
 
 		self._lastWrite=-1
-		self.dataFile=None
+		self._dataFile=None
 
 	def serve(self):
 		while True:
-			with Connection(self.ss) as (incoming,outcoming):
+			with Connection(self._ss) as (incoming, outcoming):
 				try:
 					while True:
 						if not self._serveOne(incoming,outcoming): return
@@ -58,7 +58,7 @@ class Server:
 
 		if jsonData["command"]=="init":
 			assert jsonData["blockSize"]==self.BLOCK_SIZE
-			assert jsonData["blockCount"]==self.tree.leafCount
+			assert jsonData["blockCount"]==self._tree.leafCount
 			outcoming.writeMsg({"command": "ack"})
 
 		elif jsonData["command"]=="req":
@@ -78,8 +78,8 @@ class Server:
 
 	def _requestHash(self,jsonData):
 		log.info("received request for node #{0}".format(jsonData["index"]))
-		assert jsonData["index"]<len(self.tree.store)
-		nodeHash=self.tree.store[jsonData["index"]]
+		assert jsonData["index"]<len(self._tree.store)
+		nodeHash=self._tree.store[jsonData["index"]]
 
 		jsonResponse={"command":"send", "index":jsonData["index"], "dataType":"hash"}
 		binResponse=nodeHash
@@ -89,25 +89,25 @@ class Server:
 	def _receiveData(self,jsonData,binData):
 		log.info("received data block #{0}: {1}...{2}".format(jsonData["index"],binData[:5],binData[-5:]))
 
-		if not self.dataFile:
-			self.dataFile=open(self.filename,mode="rb+")
+		if not self._dataFile:
+			self._dataFile=open(self._filename, mode="rb+")
 		i=jsonData["index"]
 		if self._lastWrite+1!=i:
-			self.dataFile.seek(i*self.BLOCK_SIZE)
-		self.dataFile.write(binData)
+			self._dataFile.seek(i * self.BLOCK_SIZE)
+		self._dataFile.write(binData)
 		self._lastWrite=i
 		if self._treeFile:
-			self._newLeaves[i+self.tree.leafStart]=hashlib.sha256(binData).digest()[HashTree.HASH_LEN:]
+			self._newLeaves[i + self._tree.leafStart]= hashlib.sha256(binData).digest()[HashTree.HASH_LEN:]
 
 		return ({"command": "ack", "index": i},)
 
 	def _finalize(self):
 		log.info("closing session...")
-		if self.dataFile:
-			self.dataFile.close()
+		if self._dataFile:
+			self._dataFile.close()
 		if self._treeFile:
 			log.info("updating hash tree...")
 			for (k,v) in self._newLeaves.values():
-				self.tree.updateLeaf(k,v)
-			self.tree.save(self._treeFile)
+				self._tree.updateLeaf(k, v)
+			self._tree.save(self._treeFile)
 		log.info("done")