diff --git a/Makefile b/Makefile
index 3bbd7f7..7106381 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@ dnsseed: dns.o bitcoin.o netbase.o protocol.o db.o main.o util.o
 	g++ -pthread $(LDFLAGS) -o dnsseed dns.o bitcoin.o netbase.o protocol.o db.o main.o util.o -lcrypto
 
 %.o: %.cpp bitcoin.h netbase.h protocol.h db.h serialize.h uint256.h util.h
-	g++ -DUSE_IPV6 -pthread $(CXXFLAGS) -Wno-invalid-offsetof -c -o $@ $<
+	g++ -pthread $(CXXFLAGS) -Wno-invalid-offsetof -c -o $@ $<
 
 dns.o: dns.c
 	gcc -pthread -std=c99 $(CXXFLAGS) dns.c -c -o dns.o
diff --git a/dns.c b/dns.c
index d634b0e..ee2f29d 100644
--- a/dns.c
+++ b/dns.c
@@ -18,18 +18,18 @@
 
 #if defined IP_RECVDSTADDR
 # define DSTADDR_SOCKOPT IP_RECVDSTADDR
-# define DSTADDR_DATASIZE (CMSG_SPACE(sizeof(struct in_addr)))
+# define DSTADDR_DATASIZE (CMSG_SPACE(sizeof(struct in6_addr)))
 # define dstaddr(x) (CMSG_DATA(x))
-#elif defined IP_PKTINFO
-struct in_pktinfo {
-  unsigned int   ipi_ifindex;  /* Interface index */
-  struct in_addr ipi_spec_dst; /* Local address */
-  struct in_addr ipi_addr;     /* Header Destination address */
-};
+#elif defined IPV6_PKTINFO
+struct in6_pktinfo
+  {
+    struct in6_addr ipi6_addr;	/* src/dst IPv6 address */
+    unsigned int ipi6_ifindex;	/* send/recv interface index */
+  };
 
-# define DSTADDR_SOCKOPT IP_PKTINFO
-# define DSTADDR_DATASIZE (CMSG_SPACE(sizeof(struct in_pktinfo)))
-# define dstaddr(x) (&(((struct in_pktinfo *)(CMSG_DATA(x)))->ipi_addr))
+# define DSTADDR_SOCKOPT IPV6_PKTINFO
+# define DSTADDR_DATASIZE (CMSG_SPACE(sizeof(struct in6_pktinfo)))
+# define dstaddr(x) (&(((struct in6_pktinfo *)(CMSG_DATA(x)))->ipi6_addr))
 #else
 # error "can't determine socket option"
 #endif
@@ -380,31 +380,31 @@ error:
 static int listenSocket = -1;
 
 int dnsserver(dns_opt_t *opt) {
-  struct sockaddr_in si_other;
+  struct sockaddr_in6 si_other;
   int senderSocket = -1;
-  senderSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+  senderSocket = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
   if (senderSocket == -1) 
     return -3;
 
   int replySocket;
   if (listenSocket == -1) {
-    struct sockaddr_in si_me;
-    if ((listenSocket=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))==-1) {
+    struct sockaddr_in6 si_me;
+    if ((listenSocket=socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP))==-1) {
       listenSocket = -1;
       return -1;
     }
-    replySocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+    replySocket = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
     if (replySocket == -1)
     {
       close(listenSocket);
       return -1;
     }
     int sockopt = 1;
-    setsockopt(listenSocket, IPPROTO_IP, DSTADDR_SOCKOPT, &sockopt, sizeof sockopt);
+    setsockopt(listenSocket, IPPROTO_IPV6, DSTADDR_SOCKOPT, &sockopt, sizeof sockopt);
     memset((char *) &si_me, 0, sizeof(si_me));
-    si_me.sin_family = AF_INET;
-    si_me.sin_port = htons(opt->port);
-    si_me.sin_addr.s_addr = INADDR_ANY;
+    si_me.sin6_family = AF_INET6;
+    si_me.sin6_port = htons(opt->port);
+    si_me.sin6_addr = in6addr_any;
     if (bind(listenSocket, (struct sockaddr*)&si_me, sizeof(si_me))==-1)
       return -2;
   }
@@ -428,7 +428,7 @@ int dnsserver(dns_opt_t *opt) {
   for (; 1; ++(opt->nRequests))
   {
     ssize_t insize = recvmsg(listenSocket, &msg, 0);
-    unsigned char *addr = (unsigned char*)&si_other.sin_addr.s_addr;
+//    unsigned char *addr = (unsigned char*)&si_other.sin_addr.s_addr;
 //    printf("DNS: Request %llu from %i.%i.%i.%i:%i of %i bytes\n", (unsigned long long)(opt->nRequests), addr[0], addr[1], addr[2], addr[3], ntohs(si_other.sin_port), (int)insize);
     if (insize <= 0)
       continue;
diff --git a/main.cpp b/main.cpp
index f7b2ccc..4dc12d5 100644
--- a/main.cpp
+++ b/main.cpp
@@ -204,14 +204,12 @@ public:
           memcpy(&a.data.v4, &addr, 4);
           cache.push_back(a);
           nIPv4++;
-#ifdef USE_IPV6
         } else if ((*it).GetIn6Addr(&addr6)) {
           addr_t a;
           a.v = 6;
           memcpy(&a.data.v6, &addr6, 16);
           cache.push_back(a);
           nIPv6++;
-#endif
         }
       }
       cacheHits = 0;
diff --git a/netbase.cpp b/netbase.cpp
index aa6df6d..c866d35 100644
--- a/netbase.cpp
+++ b/netbase.cpp
@@ -74,18 +74,10 @@ bool static LookupIntern(const char *pszName, std::vector<CNetAddr>& vIP, unsign
     aiHint.ai_socktype = SOCK_STREAM;
     aiHint.ai_protocol = IPPROTO_TCP;
 #ifdef WIN32
-#  ifdef USE_IPV6
     aiHint.ai_family = AF_UNSPEC;
-#  else
-    aiHint.ai_family = AF_INET;
-#  endif
     aiHint.ai_flags = fAllowLookup ? 0 : AI_NUMERICHOST;
 #else
-#  ifdef USE_IPV6
     aiHint.ai_family = AF_UNSPEC;
-#  else
-    aiHint.ai_family = AF_INET;
-#  endif
     aiHint.ai_flags = fAllowLookup ? AI_ADDRCONFIG : AI_NUMERICHOST;
 #endif
     struct addrinfo *aiRes = NULL;
@@ -102,13 +94,11 @@ bool static LookupIntern(const char *pszName, std::vector<CNetAddr>& vIP, unsign
             vIP.push_back(CNetAddr(((struct sockaddr_in*)(aiTrav->ai_addr))->sin_addr));
         }
 
-#ifdef USE_IPV6
         if (aiTrav->ai_family == AF_INET6)
         {
             assert(aiTrav->ai_addrlen >= sizeof(sockaddr_in6));
             vIP.push_back(CNetAddr(((struct sockaddr_in6*)(aiTrav->ai_addr))->sin6_addr));
         }
-#endif
 
         aiTrav = aiTrav->ai_next;
     }
@@ -323,11 +313,7 @@ bool static ConnectSocketDirectly(const CService &addrConnect, SOCKET& hSocketRe
 {
     hSocketRet = INVALID_SOCKET;
 
-#ifdef USE_IPV6
     struct sockaddr_storage sockaddr;
-#else
-    struct sockaddr sockaddr;
-#endif
     socklen_t len = sizeof(sockaddr);
     if (!addrConnect.GetSockAddr((struct sockaddr*)&sockaddr, &len)) {
         printf("Cannot connect to %s: unsupported network\n", addrConnect.ToString().c_str());
@@ -578,12 +564,10 @@ CNetAddr::CNetAddr(const struct in_addr& ipv4Addr)
     memcpy(ip+12, &ipv4Addr, 4);
 }
 
-#ifdef USE_IPV6
 CNetAddr::CNetAddr(const struct in6_addr& ipv6Addr)
 {
     memcpy(ip, &ipv6Addr, 16);
 }
-#endif
 
 CNetAddr::CNetAddr(const char *pszIp, bool fAllowLookup)
 {
@@ -772,11 +756,7 @@ std::string CNetAddr::ToStringIP() const
     if (IsI2P())
         return EncodeBase32(&ip[6], 10) + ".oc.b32.i2p";
     CService serv(*this, 0);
-#ifdef USE_IPV6
     struct sockaddr_storage sockaddr;
-#else
-    struct sockaddr sockaddr;
-#endif
     socklen_t socklen = sizeof(sockaddr);
     if (serv.GetSockAddr((struct sockaddr*)&sockaddr, &socklen)) {
         char name[1025] = "";
@@ -821,13 +801,11 @@ bool CNetAddr::GetInAddr(struct in_addr* pipv4Addr) const
     return true;
 }
 
-#ifdef USE_IPV6
 bool CNetAddr::GetIn6Addr(struct in6_addr* pipv6Addr) const
 {
     memcpy(pipv6Addr, ip, 16);
     return true;
 }
-#endif
 
 // get canonical identifier of an address' group
 // no two connections will be attempted to addresses with the same group
@@ -1013,23 +991,19 @@ CService::CService(const struct in_addr& ipv4Addr, unsigned short portIn) : CNet
 {
 }
 
-#ifdef USE_IPV6
 CService::CService(const struct in6_addr& ipv6Addr, unsigned short portIn) : CNetAddr(ipv6Addr), port(portIn)
 {
 }
-#endif
 
 CService::CService(const struct sockaddr_in& addr) : CNetAddr(addr.sin_addr), port(ntohs(addr.sin_port))
 {
     assert(addr.sin_family == AF_INET);
 }
 
-#ifdef USE_IPV6
 CService::CService(const struct sockaddr_in6 &addr) : CNetAddr(addr.sin6_addr), port(ntohs(addr.sin6_port))
 {
    assert(addr.sin6_family == AF_INET6);
 }
-#endif
 
 bool CService::SetSockAddr(const struct sockaddr *paddr)
 {
@@ -1037,11 +1011,9 @@ bool CService::SetSockAddr(const struct sockaddr *paddr)
     case AF_INET:
         *this = CService(*(const struct sockaddr_in*)paddr);
         return true;
-#ifdef USE_IPV6
     case AF_INET6:
         *this = CService(*(const struct sockaddr_in6*)paddr);
         return true;
-#endif
     default:
         return false;
     }
@@ -1113,7 +1085,6 @@ bool CService::GetSockAddr(struct sockaddr* paddr, socklen_t *addrlen) const
         paddrin->sin_port = htons(port);
         return true;
     }
-#ifdef USE_IPV6
     if (IsIPv6()) {
         if (*addrlen < (socklen_t)sizeof(struct sockaddr_in6))
             return false;
@@ -1126,7 +1097,6 @@ bool CService::GetSockAddr(struct sockaddr* paddr, socklen_t *addrlen) const
         paddrin6->sin6_port = htons(port);
         return true;
     }
-#endif
     return false;
 }
 
diff --git a/netbase.h b/netbase.h
index a7dec78..d222177 100644
--- a/netbase.h
+++ b/netbase.h
@@ -74,10 +74,8 @@ class CNetAddr
         int GetReachabilityFrom(const CNetAddr *paddrPartner = NULL) const;
         void print() const;
 
-#ifdef USE_IPV6
         CNetAddr(const struct in6_addr& pipv6Addr);
         bool GetIn6Addr(struct in6_addr* pipv6Addr) const;
-#endif
 
         friend bool operator==(const CNetAddr& a, const CNetAddr& b);
         friend bool operator!=(const CNetAddr& a, const CNetAddr& b);
@@ -118,10 +116,8 @@ class CService : public CNetAddr
         std::string ToStringIPPort() const;
         void print() const;
 
-#ifdef USE_IPV6
         CService(const struct in6_addr& ipv6Addr, unsigned short port);
         CService(const struct sockaddr_in6& addr);
-#endif
 
         IMPLEMENT_SERIALIZE
             (