diff --git a/src/engine/client/client.cpp b/src/engine/client/client.cpp
index e981ae3b6..76f35d12e 100644
--- a/src/engine/client/client.cpp
+++ b/src/engine/client/client.cpp
@@ -1022,7 +1022,7 @@ void CClient::ProcessServerPacket(CNetChunk *pPacket)
 	if(Sys)
 	{
 		// system message
-		if(Msg == NETMSG_MAP_CHANGE)
+		if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && Msg == NETMSG_MAP_CHANGE)
 		{
 			const char *pMap = Unpacker.GetString(CUnpacker::SANITIZE_CC|CUnpacker::SKIP_START_WHITESPACES);
 			int MapCrc = Unpacker.GetInt();
@@ -1088,7 +1088,7 @@ void CClient::ProcessServerPacket(CNetChunk *pPacket)
 				}
 			}
 		}
-		else if(Msg == NETMSG_MAP_DATA)
+		else if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && Msg == NETMSG_MAP_DATA)
 		{
 			if(!m_MapdownloadFile)
 				return;
@@ -1133,7 +1133,7 @@ void CClient::ProcessServerPacket(CNetChunk *pPacket)
 					m_pConsole->Print(IConsole::OUTPUT_LEVEL_DEBUG, "client/network", "requested next chunk package");
 			}
 		}
-		else if(Msg == NETMSG_CON_READY)
+		else if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && Msg == NETMSG_CON_READY)
 		{
 			GameClient()->OnConnected();
 		}
@@ -1142,7 +1142,7 @@ void CClient::ProcessServerPacket(CNetChunk *pPacket)
 			CMsgPacker Msg(NETMSG_PING_REPLY, true);
 			SendMsg(&Msg, 0);
 		}
-		else if(Msg == NETMSG_RCON_CMD_ADD)
+		else if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && Msg == NETMSG_RCON_CMD_ADD)
 		{
 			const char *pName = Unpacker.GetString(CUnpacker::SANITIZE_CC);
 			const char *pHelp = Unpacker.GetString(CUnpacker::SANITIZE_CC);
@@ -1150,25 +1150,25 @@ void CClient::ProcessServerPacket(CNetChunk *pPacket)
 			if(Unpacker.Error() == 0)
 				m_pConsole->RegisterTemp(pName, pParams, CFGFLAG_SERVER, pHelp);
 		}
-		else if(Msg == NETMSG_RCON_CMD_REM)
+		else if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && Msg == NETMSG_RCON_CMD_REM)
 		{
 			const char *pName = Unpacker.GetString(CUnpacker::SANITIZE_CC);
 			if(Unpacker.Error() == 0)
 				m_pConsole->DeregisterTemp(pName);
 		}
-		else if(Msg == NETMSG_RCON_AUTH_ON)
+		else if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && Msg == NETMSG_RCON_AUTH_ON)
 		{
 			m_RconAuthed = 1;
 			m_UseTempRconCommands = 1;
 		}
-		else if(Msg == NETMSG_RCON_AUTH_OFF)
+		else if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && Msg == NETMSG_RCON_AUTH_OFF)
 		{
 			m_RconAuthed = 0;
 			if(m_UseTempRconCommands)
 				m_pConsole->DeregisterTempAll();
 			m_UseTempRconCommands = 0;
 		}
-		else if(Msg == NETMSG_RCON_LINE)
+		else if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && Msg == NETMSG_RCON_LINE)
 		{
 			const char *pLine = Unpacker.GetString();
 			if(Unpacker.Error() == 0)
@@ -1395,11 +1395,14 @@ void CClient::ProcessServerPacket(CNetChunk *pPacket)
 	}
 	else
 	{
-		// game message
-		GameClient()->OnMessage(Msg, &Unpacker);
+		if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0)
+		{
+			// game message
+			GameClient()->OnMessage(Msg, &Unpacker);
 
-		if(m_RecordGameMessage && m_DemoRecorder.IsRecording())
-			m_DemoRecorder.RecordMessage(pPacket->m_pData, pPacket->m_DataSize);
+			if(m_RecordGameMessage && m_DemoRecorder.IsRecording())
+				m_DemoRecorder.RecordMessage(pPacket->m_pData, pPacket->m_DataSize);
+		}
 	}
 }
 
diff --git a/src/engine/server/server.cpp b/src/engine/server/server.cpp
index ac9f78abc..d5a97eae9 100644
--- a/src/engine/server/server.cpp
+++ b/src/engine/server/server.cpp
@@ -816,7 +816,7 @@ void CServer::ProcessClientPacket(CNetChunk *pPacket)
 		// system message
 		if(Msg == NETMSG_INFO)
 		{
-			if(m_aClients[ClientID].m_State == CClient::STATE_AUTH)
+			if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && m_aClients[ClientID].m_State == CClient::STATE_AUTH)
 			{
 				const char *pVersion = Unpacker.GetString(CUnpacker::SANITIZE_CC);
 				if(str_comp(pVersion, GameServer()->NetVersion()) != 0)
@@ -842,7 +842,7 @@ void CServer::ProcessClientPacket(CNetChunk *pPacket)
 		}
 		else if(Msg == NETMSG_REQUEST_MAP_DATA)
 		{
-			if(m_aClients[ClientID].m_State == CClient::STATE_CONNECTING)
+			if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) == 0 || m_aClients[ClientID].m_State == CClient::STATE_CONNECTING)
 			{
 				int ChunkSize = MAP_CHUNK_SIZE;
 
@@ -876,7 +876,7 @@ void CServer::ProcessClientPacket(CNetChunk *pPacket)
 		}
 		else if(Msg == NETMSG_READY)
 		{
-			if(m_aClients[ClientID].m_State == CClient::STATE_CONNECTING)
+			if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && m_aClients[ClientID].m_State == CClient::STATE_CONNECTING)
 			{
 				char aAddrStr[NETADDR_MAXSTRSIZE];
 				net_addr_str(m_NetServer.ClientAddr(ClientID), aAddrStr, sizeof(aAddrStr), true);
@@ -891,7 +891,7 @@ void CServer::ProcessClientPacket(CNetChunk *pPacket)
 		}
 		else if(Msg == NETMSG_ENTERGAME)
 		{
-			if(m_aClients[ClientID].m_State == CClient::STATE_READY && GameServer()->IsClientReady(ClientID))
+			if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && m_aClients[ClientID].m_State == CClient::STATE_READY && GameServer()->IsClientReady(ClientID))
 			{
 				char aAddrStr[NETADDR_MAXSTRSIZE];
 				net_addr_str(m_NetServer.ClientAddr(ClientID), aAddrStr, sizeof(aAddrStr), true);
@@ -959,7 +959,7 @@ void CServer::ProcessClientPacket(CNetChunk *pPacket)
 		{
 			const char *pCmd = Unpacker.GetString();
 
-			if(Unpacker.Error() == 0 && m_aClients[ClientID].m_Authed)
+			if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && Unpacker.Error() == 0 && m_aClients[ClientID].m_Authed)
 			{
 				char aBuf[256];
 				str_format(aBuf, sizeof(aBuf), "ClientID=%d rcon='%s'", ClientID, pCmd);
@@ -977,7 +977,7 @@ void CServer::ProcessClientPacket(CNetChunk *pPacket)
 		{
 			const char *pPw = Unpacker.GetString(CUnpacker::SANITIZE_CC);
 
-			if(Unpacker.Error() == 0)
+			if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && Unpacker.Error() == 0)
 			{
 				if(g_Config.m_SvRconPassword[0] == 0 && g_Config.m_SvRconModPassword[0] == 0)
 				{
@@ -1057,7 +1057,7 @@ void CServer::ProcessClientPacket(CNetChunk *pPacket)
 	else
 	{
 		// game message
-		if(m_aClients[ClientID].m_State >= CClient::STATE_READY)
+		if((pPacket->m_Flags&NET_CHUNKFLAG_VITAL) != 0 && m_aClients[ClientID].m_State >= CClient::STATE_READY)
 			GameServer()->OnMessage(Msg, &Unpacker, ClientID);
 	}
 }
diff --git a/src/engine/shared/network.cpp b/src/engine/shared/network.cpp
index 53110c1b0..eec88dfe0 100644
--- a/src/engine/shared/network.cpp
+++ b/src/engine/shared/network.cpp
@@ -80,7 +80,7 @@ int CNetRecvUnpacker::FetchChunk(CNetChunk *pChunk)
 		// fill in the info
 		pChunk->m_ClientID = m_ClientID;
 		pChunk->m_Address = m_Addr;
-		pChunk->m_Flags = 0;
+		pChunk->m_Flags = Header.m_Flags;
 		pChunk->m_DataSize = Header.m_Size;
 		pChunk->m_pData = pData;
 		return 1;
diff --git a/src/engine/shared/network.h b/src/engine/shared/network.h
index b555b8267..dc8ad98fb 100644
--- a/src/engine/shared/network.h
+++ b/src/engine/shared/network.h
@@ -138,6 +138,7 @@ class CNetConnection
 private:
 	unsigned short m_Sequence;
 	unsigned short m_Ack;
+	unsigned short m_PeerAck;
 	unsigned m_State;
 
 	int m_Token;
diff --git a/src/engine/shared/network_conn.cpp b/src/engine/shared/network_conn.cpp
index cd2df048e..7d76d585f 100644
--- a/src/engine/shared/network_conn.cpp
+++ b/src/engine/shared/network_conn.cpp
@@ -13,6 +13,7 @@ void CNetConnection::Reset()
 {
 	m_Sequence = 0;
 	m_Ack = 0;
+	m_PeerAck = 0;
 	m_RemoteClosed = 0;
 
 	m_State = NET_CONNSTATE_OFFLINE;
@@ -196,6 +197,19 @@ void CNetConnection::Disconnect(const char *pReason)
 
 int CNetConnection::Feed(CNetPacketConstruct *pPacket, NETADDR *pAddr)
 {
+	// check if actual ack value is valid(own sequence..latest peer ack)
+	if(m_Sequence >= m_PeerAck)
+	{
+		if(pPacket->m_Ack < m_PeerAck || pPacket->m_Ack > m_Sequence)
+			return 0;
+	}
+	else
+	{
+		if(pPacket->m_Ack < m_PeerAck && pPacket->m_Ack > m_Sequence)
+			return 0;
+	}
+	m_PeerAck = pPacket->m_Ack;
+
 	int64 Now = time_get();
 
 	// check if resend is requested
diff --git a/src/game/server/entities/character.cpp b/src/game/server/entities/character.cpp
index bf739da39..4fc24514c 100644
--- a/src/game/server/entities/character.cpp
+++ b/src/game/server/entities/character.cpp
@@ -350,7 +350,7 @@ void CCharacter::FireWeapon()
 			for(unsigned i = 0; i < sizeof(CNetObj_Projectile)/sizeof(int); i++)
 				Msg.AddInt(((int *)&p)[i]);
 
-			Server()->SendMsg(&Msg, 0, m_pPlayer->GetCID());
+			Server()->SendMsg(&Msg, MSGFLAG_VITAL, m_pPlayer->GetCID());
 
 			GameServer()->CreateSound(m_Pos, SOUND_GUN_FIRE);
 		} break;
@@ -384,7 +384,7 @@ void CCharacter::FireWeapon()
 					Msg.AddInt(((int *)&p)[i]);
 			}
 
-			Server()->SendMsg(&Msg, 0,m_pPlayer->GetCID());
+			Server()->SendMsg(&Msg, MSGFLAG_VITAL, m_pPlayer->GetCID());
 
 			GameServer()->CreateSound(m_Pos, SOUND_SHOTGUN_FIRE);
 		} break;
@@ -406,7 +406,7 @@ void CCharacter::FireWeapon()
 			Msg.AddInt(1);
 			for(unsigned i = 0; i < sizeof(CNetObj_Projectile)/sizeof(int); i++)
 				Msg.AddInt(((int *)&p)[i]);
-			Server()->SendMsg(&Msg, 0, m_pPlayer->GetCID());
+			Server()->SendMsg(&Msg, MSGFLAG_VITAL, m_pPlayer->GetCID());
 
 			GameServer()->CreateSound(m_Pos, SOUND_GRENADE_FIRE);
 		} break;