diff --git a/apps/openmw-mp/MasterClient.cpp b/apps/openmw-mp/MasterClient.cpp
index 36de134e1..a13718d42 100644
--- a/apps/openmw-mp/MasterClient.cpp
+++ b/apps/openmw-mp/MasterClient.cpp
@@ -83,7 +83,7 @@ void MasterClient::SetRuleString(std::string key, std::string value)
     {
         ServerRule rule;
         rule.str = value;
-        rule.type = 's';
+        rule.type = ServerRule::Type::string;
         queryData.rules.insert({key, rule});
         updated = true;
     }
@@ -98,7 +98,7 @@ void MasterClient::SetRuleValue(std::string key, double value)
     {
         ServerRule rule;
         rule.val = value;
-        rule.type = 'v';
+        rule.type = ServerRule::Type::number;
         queryData.rules.insert({key, rule});
         updated = true;
     }
diff --git a/components/openmw-mp/Master/MasterData.hpp b/components/openmw-mp/Master/MasterData.hpp
index e553b3710..ef85e1adc 100644
--- a/components/openmw-mp/Master/MasterData.hpp
+++ b/components/openmw-mp/Master/MasterData.hpp
@@ -6,6 +6,7 @@
 #define NEWMASTERPROTO_MASTERDATA_HPP
 
 #include <string>
+#include <utility>
 #include <vector>
 #include <map>
 #include <list>
@@ -20,7 +21,11 @@ enum MASTER_PACKETS
 
 struct ServerRule
 {
-    char type;
+    enum Type : char
+    {
+        string = 's',
+        number = 'v'
+    } type;
 
     std::string str;
     double val;
@@ -30,48 +35,54 @@ struct Plugin
 {
     std::string name;
     unsigned hash;
-    Plugin(std::string name = "", unsigned hash = 0): name(name), hash(hash) {};
+    Plugin(std::string name = "", unsigned hash = 0): name(std::move(name)), hash(hash) {};
 };
 
 struct QueryData
 {
     QueryData()
     {
-        rules["name"].type = 's';
+        rules["name"].type = ServerRule::Type::string;
         rules["name"].str = "";
-        rules["version"].type = 's';
+        rules["version"].type = ServerRule::Type::string;
         rules["version"].str = "";
-        rules["players"].type = 'v';
+        rules["players"].type = ServerRule::Type::number;
         rules["players"].val = 0;
-        rules["maxPlayers"].type = 'v';
+        rules["maxPlayers"].type = ServerRule::Type::number;
         rules["maxPlayers"].val = 0;
-        rules["gamemode"].type = 's';
+        rules["gamemode"].type = ServerRule::Type::string;
         rules["gamemode"].str = "";
-        rules["passw"].type = 'v';
+        rules["passw"].type = ServerRule::Type::number;
         rules["passw"].val = 0;
     }
-    const char *GetName() { return rules["name"].str.c_str(); }
+    const char *GetName() const { return rules.at("name").str.c_str(); }
     void SetName(const char *name) { rules["name"].str = name; }
 
-    const char *GetVersion() { return rules["version"].str.c_str(); }
+    const char *GetVersion() const { return rules.at("version").str.c_str(); }
     void SetVersion(const char *version) { rules["version"].str = version; }
 
-    int GetPlayers() { return rules["players"].val; }
+    int GetPlayers() const { return rules.at("players").val; }
     void SetPlayers(int players) { rules["players"].val = players; }
 
-    int GetMaxPlayers() { return rules["maxPlayers"].val; }
+    int GetMaxPlayers() const { return rules.at("maxPlayers").val; }
     void SetMaxPlayers(int players) { rules["maxPlayers"].val = players; }
 
-    const char *GetGameMode() { return rules["gamemode"].str.c_str(); }
+    const char *GetGameMode() const { return rules.at("gamemode").str.c_str(); }
     void SetGameMode(const char *str) { rules["gamemode"].str = str; }
 
     void SetPassword(int value) { rules["passw"].val = value; };
-    int GetPassword() { return rules["passw"].val; }
+    int GetPassword() const { return rules.at("passw").val; }
 
 
     std::vector<std::string> players;
     std::map<std::string, ServerRule> rules;
     std::vector<Plugin> plugins;
+    const static int predefinedRules = 6;
+    const static int maxRules = 128;
+    const static int maxUserRules = maxRules - predefinedRules;
+    const static int maxPlayers = 100; // will shown only maxPlayers players
+    const static int maxPlugins = 256;
+    const static int maxStringLength = 256;
 };
 
 #endif //NEWMASTERPROTO_MASTERDATA_HPP
diff --git a/components/openmw-mp/Master/PacketMasterAnnounce.cpp b/components/openmw-mp/Master/PacketMasterAnnounce.cpp
index ac8b3cecb..ff22b6465 100644
--- a/components/openmw-mp/Master/PacketMasterAnnounce.cpp
+++ b/components/openmw-mp/Master/PacketMasterAnnounce.cpp
@@ -35,7 +35,7 @@ void PacketMasterAnnounce::SetServer(QueryData *_server)
     server = _server;
 }
 
-void PacketMasterAnnounce::SetFunc(int _func)
+void PacketMasterAnnounce::SetFunc(uint32_t _func)
 {
     func = _func;
 }
diff --git a/components/openmw-mp/Master/PacketMasterAnnounce.hpp b/components/openmw-mp/Master/PacketMasterAnnounce.hpp
index 4a3a81be0..5af7ad4e0 100644
--- a/components/openmw-mp/Master/PacketMasterAnnounce.hpp
+++ b/components/openmw-mp/Master/PacketMasterAnnounce.hpp
@@ -15,12 +15,12 @@ namespace mwmp
     {
         friend class ProxyMasterPacket;
     public:
-        PacketMasterAnnounce(RakNet::RakPeerInterface *peer);
+        explicit PacketMasterAnnounce(RakNet::RakPeerInterface *peer);
 
-        virtual void Packet(RakNet::BitStream *bs, bool send);
+        void Packet(RakNet::BitStream *bs, bool send) override;
 
         void SetServer(QueryData *server);
-        void SetFunc(int keep);
+        void SetFunc(uint32_t keep);
         int GetFunc();
 
         enum Func
@@ -31,7 +31,7 @@ namespace mwmp
         };
     private:
         QueryData *server;
-        int func;
+        uint32_t func;
     };
 }
 
diff --git a/components/openmw-mp/Master/PacketMasterQuery.cpp b/components/openmw-mp/Master/PacketMasterQuery.cpp
index 1850de6c5..c14e32d3e 100644
--- a/components/openmw-mp/Master/PacketMasterQuery.cpp
+++ b/components/openmw-mp/Master/PacketMasterQuery.cpp
@@ -26,7 +26,7 @@ void PacketMasterQuery::Packet(RakNet::BitStream *bs, bool send)
     if (send)
         bs->Write(packetID);
 
-    int serversCount = servers->size();
+    int32_t serversCount = servers->size();
 
     RW(serversCount, send);
 
@@ -36,7 +36,7 @@ void PacketMasterQuery::Packet(RakNet::BitStream *bs, bool send)
 
     QueryData server;
     string addr;
-    unsigned short port;
+    uint16_t port;
     while (serversCount--)
     {
         if (send)
@@ -50,6 +50,12 @@ void PacketMasterQuery::Packet(RakNet::BitStream *bs, bool send)
 
         ProxyMasterPacket::addServer(this, server, send);
 
+        if(addr.empty())
+        {
+            std::cerr << "Address empty. Aborting PacketMasterQuery::Packet" << std::endl;
+            return;
+        }
+
         if (send)
             serverIt++;
         else
diff --git a/components/openmw-mp/Master/PacketMasterQuery.hpp b/components/openmw-mp/Master/PacketMasterQuery.hpp
index ada4b308d..43eeafee0 100644
--- a/components/openmw-mp/Master/PacketMasterQuery.hpp
+++ b/components/openmw-mp/Master/PacketMasterQuery.hpp
@@ -15,9 +15,9 @@ namespace mwmp
     {
         friend class ProxyMasterPacket;
     public:
-        PacketMasterQuery(RakNet::RakPeerInterface *peer);
+        explicit PacketMasterQuery(RakNet::RakPeerInterface *peer);
 
-        virtual void Packet(RakNet::BitStream *bs, bool send);
+        void Packet(RakNet::BitStream *bs, bool send) override;
 
         void SetServers(std::map<RakNet::SystemAddress, QueryData> *serverMap);
     private:
diff --git a/components/openmw-mp/Master/PacketMasterUpdate.cpp b/components/openmw-mp/Master/PacketMasterUpdate.cpp
index 54f32e266..33ef10ec4 100644
--- a/components/openmw-mp/Master/PacketMasterUpdate.cpp
+++ b/components/openmw-mp/Master/PacketMasterUpdate.cpp
@@ -24,7 +24,7 @@ void PacketMasterUpdate::Packet(RakNet::BitStream *bs, bool send)
         bs->Write(packetID);
 
     string addr = server->first.ToString(false);
-    unsigned short port = server->first.GetPort();
+    uint16_t port = server->first.GetPort();
 
     RW(addr, send);
     RW(port, send);
diff --git a/components/openmw-mp/Master/PacketMasterUpdate.hpp b/components/openmw-mp/Master/PacketMasterUpdate.hpp
index 37adf2216..f3c254dbb 100644
--- a/components/openmw-mp/Master/PacketMasterUpdate.hpp
+++ b/components/openmw-mp/Master/PacketMasterUpdate.hpp
@@ -15,9 +15,9 @@ namespace mwmp
     {
         friend class ProxyMasterPacket;
     public:
-        PacketMasterUpdate(RakNet::RakPeerInterface *peer);
+        explicit PacketMasterUpdate(RakNet::RakPeerInterface *peer);
 
-        virtual void Packet(RakNet::BitStream *bs, bool send);
+        void Packet(RakNet::BitStream *bs, bool send) override;
 
         void SetServer(std::pair<RakNet::SystemAddress, QueryData> *serverPair);
     private:
diff --git a/components/openmw-mp/Master/ProxyMasterPacket.hpp b/components/openmw-mp/Master/ProxyMasterPacket.hpp
index d5d4506b5..a9920d424 100644
--- a/components/openmw-mp/Master/ProxyMasterPacket.hpp
+++ b/components/openmw-mp/Master/ProxyMasterPacket.hpp
@@ -14,9 +14,8 @@ namespace mwmp
     class ProxyMasterPacket : public BasePacket
     {
     private:
-        ProxyMasterPacket(RakNet::RakPeerInterface *peer) : BasePacket(peer)
+        explicit ProxyMasterPacket(RakNet::RakPeerInterface *peer) : BasePacket(peer)
         {
-
         }
 
     public:
@@ -25,11 +24,10 @@ namespace mwmp
         {
             using namespace std;
 
-            int rulesSize = server.rules.size();
-
+            int32_t rulesSize = server.rules.size();
             packet->RW(rulesSize, send);
 
-            if (rulesSize > 2000)
+            if (rulesSize > QueryData::maxRules)
                 rulesSize = 0;
 
             map<string, ServerRule>::iterator ruleIt;
@@ -38,7 +36,7 @@ namespace mwmp
 
             while (rulesSize--)
             {
-                ServerRule *rule = 0;
+                ServerRule *rule = nullptr;
                 string key;
                 if (send)
                 {
@@ -46,7 +44,7 @@ namespace mwmp
                     rule = &ruleIt->second;
                 }
 
-                packet->RW(key, send);
+                packet->RW(key, send, QueryData::maxStringLength);
                 if (!send)
                 {
                     ruleIt = server.rules.insert(pair<string, ServerRule>(key, ServerRule())).first;
@@ -55,8 +53,8 @@ namespace mwmp
 
                 packet->RW(rule->type, send);
 
-                if (rule->type == 's')
-                    packet->RW(rule->str, send);
+                if (rule->type == ServerRule::Type::string)
+                    packet->RW(rule->str, send, QueryData::maxStringLength);
                 else
                     packet->RW(rule->val, send);
 
@@ -66,56 +64,38 @@ namespace mwmp
 
             vector<string>::iterator plIt;
 
-            if (send)
-                plIt = server.players.begin();
-            else
-                server.players.clear();
-
-            int playersCount = server.players.size();
+            int32_t playersCount = server.players.size();
             packet->RW(playersCount, send);
 
-            if (playersCount > 2000)
+            if (playersCount > QueryData::maxPlayers)
                 playersCount = 0;
 
-            while (playersCount--)
+            if (!send)
             {
-                string player;
-                if (send)
-                    player = *plIt;
+                server.players.clear();
+                server.players.resize(playersCount);
+            }
 
-                packet->RW(player, send);
+            for(auto &&player : server.players)
+                packet->RW(player, send, QueryData::maxStringLength);
 
-                if (!send)
-                    server.players.push_back(player);
-                else
-                    plIt++;
-            }
 
-            int pluginsCount = server.plugins.size();
+            int32_t pluginsCount = server.plugins.size();
             packet->RW(pluginsCount, send);
 
-            if (pluginsCount > 2000)
+            if (pluginsCount > QueryData::maxPlugins)
                 pluginsCount = 0;
 
-            vector<Plugin>::iterator pluginIt;
-
-            if (send)
-                pluginIt = server.plugins.begin();
-            else
+            if (!send)
+            {
                 server.plugins.clear();
+                server.plugins.resize(pluginsCount);
+            }
 
-            while (pluginsCount--)
+            for (auto &&plugin : server.plugins)
             {
-                Plugin plugin;
-                if (send)
-                    plugin = *pluginIt;
-
-                packet->RW(plugin.name, send);
+                packet->RW(plugin.name, send, QueryData::maxStringLength);
                 packet->RW(plugin.hash, send);
-                if (!send)
-                    server.plugins.push_back(plugin);
-                else
-                    pluginIt++;
             }
         }
     };