diff --git a/src/Makefile.am b/src/Makefile.am
index dfd99f1..ae2a5c8 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,4 +1,7 @@
 sbin_PROGRAMS = wrapsix-dnsproxy wrapsix-wrapper
 wrapsix_dnsproxy_SOURCES = dnsproxy.c
 wrapsix_wrapper_SOURCES = wrapper.c wrapper.h \
-			  ipv6.c ipv6.h
+			  ipv6.c ipv6.h \
+			  ipv4.h \
+			  radixtree.c radixtree.h \
+			  nat.c nat.h
diff --git a/src/ipv4.h b/src/ipv4.h
new file mode 100644
index 0000000..0d2e00a
--- /dev/null
+++ b/src/ipv4.h
@@ -0,0 +1,27 @@
+/*
+ *  WrapSix
+ *  Copyright (C) 2008-2010  Michal Zima <xhire@mujmalysvet.cz>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero 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 Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef IPV4_H
+#define IPV4_H
+
+/* IPv4 address structure */
+struct s_ipv4_addr {
+	unsigned char		addr[4];
+} __attribute__ ((__packed__));
+
+#endif /* IPV4_H */
diff --git a/src/wrapper.c b/src/wrapper.c
index 5f16045..3744452 100644
--- a/src/wrapper.c
+++ b/src/wrapper.c
@@ -27,8 +27,10 @@
 #include <sys/ioctl.h>		/* ioctl, SIOCGIFINDEX */
 #include <unistd.h>		/* close */
 
-#include "wrapper.h"
+#include "ipv4.h"
 #include "ipv6.h"
+#include "nat.h"
+#include "wrapper.h"
 
 #define INTERFACE	"eth0"
 #define BUFFER_SIZE	65536
@@ -80,6 +82,9 @@ int main(int argc, char **argv)
 	/* compute binary IPv6 address of WrapSix prefix */
 	inet_pton(AF_INET6, PREFIX, &wrapsix_ipv6_prefix);
 
+	/* initiate NAT tables */
+	nat_init();
+
 	/* sniff! :c) */
 	for (;;) {
 		addr_size = sizeof(addr);
@@ -92,6 +97,9 @@ int main(int argc, char **argv)
 	}
 
 	/* clean-up */
+	/* empty NAT tables */
+	nat_quit();
+
 	/* unset the promiscuous mode */
 	if (setsockopt(sniff_sock, SOL_PACKET, PACKET_DROP_MEMBERSHIP, (char *) &pmr, sizeof(pmr)) == -1) {
 		fprintf(stderr, "[Error] Unable to unset the promiscuous mode on the interface\n");
@@ -129,3 +137,22 @@ int process(char *packet)
 			return 1;
 	}
 }
+
+struct s_ipv4_addr ipv6_to_ipv4(struct s_ipv6_addr *ipv6_addr)
+{
+	struct s_ipv4_addr ipv4_addr;
+
+	memcpy(&ipv4_addr, &ipv6_addr + 12, 4);
+
+	return ipv4_addr;
+}
+
+struct s_ipv6_addr ipv4_to_ipv6(struct s_ipv4_addr *ipv4_addr)
+{
+	struct s_ipv6_addr ipv6_addr;
+
+	ipv6_addr = wrapsix_ipv6_prefix;
+	memcpy(&ipv6_addr + 12, &ipv4_addr, 4);
+
+	return ipv6_addr;
+}
diff --git a/src/wrapper.h b/src/wrapper.h
index ee9c430..e6deba5 100644
--- a/src/wrapper.h
+++ b/src/wrapper.h
@@ -39,4 +39,7 @@ struct s_ethernet {
 extern struct s_ipv6_addr	ndp_multicast_addr;
 extern struct s_ipv6_addr	wrapsix_ipv6_prefix;
 
+struct s_ipv4_addr ipv6_to_ipv4(struct s_ipv6_addr *ipv6_addr);
+struct s_ipv6_addr ipv4_to_ipv6(struct s_ipv4_addr *ipv4_addr);
+
 #endif /* WRAPPER_H */