diff --git a/client/streamconfigdialog.cpp b/client/streamconfigdialog.cpp
index 7789f8d..6d336e3 100644
--- a/client/streamconfigdialog.cpp
+++ b/client/streamconfigdialog.cpp
@@ -200,6 +200,8 @@ void StreamConfigDialog::setupUiExtra()
     bgProto[ProtoL3]->addButton(rbL3Ipv4, OstProto::Protocol::kIp4FieldNumber);
     bgProto[ProtoL3]->addButton(rbL3Ipv6, 0xFFFF);
     bgProto[ProtoL3]->addButton(rbL3Arp, OstProto::Protocol::kArpFieldNumber);
+    bgProto[ProtoL3]->addButton(rbL3Ip4over4, 
+            OstProto::Protocol::kIp4over4FieldNumber);
     bgProto[ProtoL3]->addButton(rbL3Other, ButtonIdOther);
 #endif
 
@@ -952,8 +954,10 @@ void StreamConfigDialog::on_tbProtocolData_currentChanged(int /*index*/)
     // Refresh protocol widgets in case there is any dependent data between 
     // protocols e.g. TCP/UDP port numbers are dependent on Port/Protocol 
     // selection in TextProtocol
+#if 0 // FIXME: temp mask to avoid crash till we fix it
     mpStream->storeProtocolWidgets();
     mpStream->loadProtocolWidgets();
+#endif
 }
 
 void StreamConfigDialog::on_pbOk_clicked()
diff --git a/client/streamconfigdialog.ui b/client/streamconfigdialog.ui
index f64c848..687b970 100644
--- a/client/streamconfigdialog.ui
+++ b/client/streamconfigdialog.ui
@@ -8,7 +8,7 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>569</width>
+    <width>579</width>
     <height>481</height>
    </rect>
   </property>
@@ -173,7 +173,7 @@ QLineEdit:enabled[inputMask = "HH HH HH HH HH HH; "] { background-color: #ccccff
            <rect>
             <x>0</x>
             <y>0</y>
-            <width>527</width>
+            <width>537</width>
             <height>243</height>
            </rect>
           </property>
@@ -339,6 +339,19 @@ QLineEdit:enabled[inputMask = "HH HH HH HH HH HH; "] { background-color: #ccccff
                </widget>
               </item>
               <item row="1" column="1" >
+               <widget class="QRadioButton" name="rbL3Ip4over4" >
+                <property name="enabled" >
+                 <bool>false</bool>
+                </property>
+                <property name="text" >
+                 <string>IP 4over4</string>
+                </property>
+                <property name="checked" >
+                 <bool>false</bool>
+                </property>
+               </widget>
+              </item>
+              <item row="1" column="2" >
                <widget class="QRadioButton" name="rbL3Other" >
                 <property name="enabled" >
                  <bool>false</bool>
diff --git a/common/comboprotocol.h b/common/comboprotocol.h
index c6efa0a..c7d4053 100644
--- a/common/comboprotocol.h
+++ b/common/comboprotocol.h
@@ -25,7 +25,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>
 template <int protoNumber, class ProtoA, class ProtoB>
 class ComboProtocol : public AbstractProtocol
 {
-private:
+protected:
     ProtoA    *protoA;
     ProtoB    *protoB;
     QWidget *configForm;
@@ -82,8 +82,7 @@ public:
 
             // NOTE: To use protoX->protoDataCopyFrom() we need to arrange
             // so that it sees its own protocolNumber() - but since the
-            // input param 'protocol' is 'const', we make a copy first
-
+            // input param 'protocol' is 'const', we work on a copy
             proto.CopyFrom(protocol);
 
             proto.mutable_protocol_id()->set_id(protoA->protocolNumber());
diff --git a/common/ip4.ui b/common/ip4.ui
index a3135e7..c457a2d 100644
--- a/common/ip4.ui
+++ b/common/ip4.ui
@@ -5,8 +5,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>527</width>
-    <height>296</height>
+    <width>493</width>
+    <height>308</height>
    </rect>
   </property>
   <property name="windowTitle" >
@@ -35,7 +35,8 @@
      <item row="1" column="0" >
       <widget class="QCheckBox" name="cbIpHdrLenOverride" >
        <property name="text" >
-        <string>Override Header Length (x4)</string>
+        <string>Override Header
+Length (x4)</string>
        </property>
       </widget>
      </item>
@@ -66,16 +67,6 @@
        </property>
       </widget>
      </item>
-     <item row="2" column="2" >
-      <widget class="QToolButton" name="toolButton" >
-       <property name="enabled" >
-        <bool>false</bool>
-       </property>
-       <property name="text" >
-        <string>...</string>
-       </property>
-      </widget>
-     </item>
      <item row="3" column="0" >
       <widget class="QCheckBox" name="cbIpLengthOverride" >
        <property name="text" >
@@ -106,13 +97,6 @@
      </item>
     </layout>
    </item>
-   <item row="0" column="1" >
-    <widget class="Line" name="line_2" >
-     <property name="orientation" >
-      <enum>Qt::Vertical</enum>
-     </property>
-    </widget>
-   </item>
    <item row="0" column="2" >
     <layout class="QGridLayout" >
      <item row="0" column="0" >
diff --git a/common/ip4over4.h b/common/ip4over4.h
new file mode 100644
index 0000000..cf6c5f5
--- /dev/null
+++ b/common/ip4over4.h
@@ -0,0 +1,101 @@
+/*
+Copyright (C) 2010 Srivats P.
+
+This file is part of "Ostinato"
+
+This is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>
+*/
+
+#ifndef _IP_4_OVER_4_H
+#define _IP_4_OVER_4_H
+
+#include "ip4over4.pb.h"
+
+#include "comboprotocol.h"
+#include "ip4.h"
+
+typedef ComboProtocol<OstProto::Protocol::kIp4over4FieldNumber, 
+    Ip4Protocol, Ip4Protocol> Ip4over4Combo;
+
+class Ip4over4Protocol : public Ip4over4Combo 
+{
+public:
+    Ip4over4Protocol(StreamBase *stream, AbstractProtocol *parent = 0)
+        : Ip4over4Combo(stream, parent) 
+    {
+    }
+
+    static Ip4over4Protocol* createInstance(StreamBase *stream,
+        AbstractProtocol *parent)
+    {
+        return new Ip4over4Protocol(stream, parent);
+    }
+
+    virtual void protoDataCopyInto(OstProto::Protocol &protocol) const
+    {
+        OstProto::Protocol tempProto;
+
+        protoA->protoDataCopyInto(tempProto);
+        protocol.MutableExtension(OstProto::ip4over4)
+            ->MutableExtension(OstProto::ip4_outer)
+            ->CopyFrom(tempProto.GetExtension(OstProto::ip4));
+
+        tempProto.Clear();
+
+        protoB->protoDataCopyInto(tempProto);
+        protocol.MutableExtension(OstProto::ip4over4)
+            ->MutableExtension(OstProto::ip4_inner)
+            ->CopyFrom(tempProto.GetExtension(OstProto::ip4));
+
+        protocol.mutable_protocol_id()->set_id(protocolNumber());
+    }
+
+    virtual void protoDataCopyFrom(const OstProto::Protocol &protocol)
+    {
+        if (protocol.protocol_id().id() == protocolNumber()
+                && protocol.HasExtension(OstProto::ip4over4))
+        {
+            OstProto::Protocol    tempProto;
+
+            // NOTE: To use protoX->protoDataCopyFrom() we need to arrange
+            // so that it sees its own protocolNumber() and its own extension
+            // in 'protocol'
+            tempProto.mutable_protocol_id()->set_id(protoA->protocolNumber());
+            tempProto.MutableExtension(OstProto::ip4)->CopyFrom(
+                    protocol.GetExtension(OstProto::ip4over4).GetExtension(
+                        OstProto::ip4_outer));
+            protoA->protoDataCopyFrom(tempProto);
+
+            tempProto.Clear();
+
+            tempProto.mutable_protocol_id()->set_id(protoB->protocolNumber());
+            tempProto.MutableExtension(OstProto::ip4)->CopyFrom(
+                    protocol.GetExtension(OstProto::ip4over4).GetExtension(
+                        OstProto::ip4_inner));
+            protoB->protoDataCopyFrom(tempProto);
+        }
+    }
+    virtual quint32 protocolFrameCksum(int streamIndex = 0,
+        CksumType cksumType = CksumIp) const
+    {
+        // For a Pseudo IP cksum, we assume it is the succeeding protocol
+        // that is requesting it and hence return protoB's cksum;
+        if (cksumType == CksumIpPseudo)
+            return protoB->protocolFrameCksum(streamIndex, cksumType);
+
+        return Ip4over4Combo::protocolFrameCksum(streamIndex, cksumType);
+    }
+};
+
+#endif
diff --git a/common/ip4over4.proto b/common/ip4over4.proto
new file mode 100644
index 0000000..df25a32
--- /dev/null
+++ b/common/ip4over4.proto
@@ -0,0 +1,37 @@
+/*
+Copyright (C) 2010 Srivats P.
+
+This file is part of "Ostinato"
+
+This is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>
+*/
+
+import "protocol.proto";
+import "ip4.proto";
+
+package OstProto;
+
+// IP 4over4 (also called IPIP)
+message Ip4over4 {
+    extensions 1 to 2;
+}
+
+extend Ip4over4 {
+    optional Ip4 ip4_outer = 1;
+    optional Ip4 ip4_inner = 2;
+}
+
+extend Protocol {
+    optional Ip4over4 ip4over4 = 132;
+}
diff --git a/common/ostproto.pro b/common/ostproto.pro
index 33567f8..89510ce 100644
--- a/common/ostproto.pro
+++ b/common/ostproto.pro
@@ -34,6 +34,7 @@ PROTOS += \
     vlanstack.proto \
     arp.proto \
     ip4.proto \
+    ip4over4.proto \
     icmp.proto \
     tcp.proto \
     udp.proto \
@@ -60,6 +61,7 @@ HEADERS += \
     vlanstack.h \
     arp.h \
     ip4.h \
+    ip4over4.h \
     icmp.h \
     tcp.h \
     udp.h \
diff --git a/common/protocol.proto b/common/protocol.proto
index bafbe8a..6f88c78 100644
--- a/common/protocol.proto
+++ b/common/protocol.proto
@@ -101,6 +101,7 @@ message Protocol {
 
         kIp4FieldNumber = 130;
         kArpFieldNumber = 131;
+        kIp4over4FieldNumber = 132;
 
         kTcpFieldNumber = 140;
         kUdpFieldNumber = 141;
diff --git a/common/protocolmanager.cpp b/common/protocolmanager.cpp
index b543ac0..e8e6570 100644
--- a/common/protocolmanager.cpp
+++ b/common/protocolmanager.cpp
@@ -33,6 +33,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>
 #include "vlanstack.h"    
 #include "arp.h"    
 #include "ip4.h"    
+#include "ip4over4.h"    
 #include "icmp.h"    
 #include "tcp.h"    
 #include "udp.h"    
@@ -49,6 +50,7 @@ ProtocolManager::ProtocolManager()
      */
     registerProtocol(OstProto::Protocol::kMacFieldNumber,
             (void*) MacProtocol::createInstance);
+
     registerProtocol(OstProto::Protocol::kEth2FieldNumber,
             (void*) Eth2Protocol::createInstance);
     registerProtocol(OstProto::Protocol::kDot3FieldNumber,
@@ -61,23 +63,27 @@ ProtocolManager::ProtocolManager()
             (void*) Dot2LlcProtocol::createInstance);
     registerProtocol(OstProto::Protocol::kDot2SnapFieldNumber,
             (void*) Dot2SnapProtocol::createInstance);
+
     registerProtocol(OstProto::Protocol::kSvlanFieldNumber,
             (void*) SVlanProtocol::createInstance);
     registerProtocol(OstProto::Protocol::kVlanFieldNumber,
             (void*) VlanProtocol::createInstance);
     registerProtocol(OstProto::Protocol::kVlanStackFieldNumber,
             (void*) VlanStackProtocol::createInstance);
+
     registerProtocol(OstProto::Protocol::kArpFieldNumber,
             (void*) ArpProtocol::createInstance);
     registerProtocol(OstProto::Protocol::kIp4FieldNumber,
             (void*) Ip4Protocol::createInstance);
+    registerProtocol(OstProto::Protocol::kIp4over4FieldNumber,
+            (void*) Ip4over4Protocol::createInstance);
+
     registerProtocol(OstProto::Protocol::kIcmpFieldNumber,
             (void*) IcmpProtocol::createInstance);
     registerProtocol(OstProto::Protocol::kTcpFieldNumber,
             (void*) TcpProtocol::createInstance);
     registerProtocol(OstProto::Protocol::kUdpFieldNumber,
             (void*) UdpProtocol::createInstance);
-
     registerProtocol(OstProto::Protocol::kTextProtocolFieldNumber,
             (void*) TextProtocol::createInstance);