diff --git a/bitcoin.cpp b/bitcoin.cpp
index 28debf9..dbfc7ee 100644
--- a/bitcoin.cpp
+++ b/bitcoin.cpp
@@ -19,7 +19,6 @@ class CNode {
   unsigned int nHeaderStart;
   unsigned int nMessageStart;
   int nVersion;
-  int nRecvVersion;
   string strSubVer;
   int nStartingHeight;
   vector<CAddress> *vAddr;
@@ -82,11 +81,6 @@ class CNode {
   }
  
   void GotVersion() {
-    if (nVersion < MIN_VERSION) {
-      printf("%s: BAD (version %i is below %i)\n", ToString(you).c_str(), nVersion, MIN_VERSION);
-      ban = 1000000;
-      return;
-    }
     printf("%s: version %i\n", ToString(you).c_str(), nVersion);
     BeginMessage("getaddr");
     EndMessage();
@@ -109,12 +103,6 @@ class CNode {
       if (nVersion >= 209 && !vRecv.empty())
         vRecv >> nStartingHeight;
       
-      if (!(you.nServices & NODE_NETWORK)) {
-        printf("%s: BAD (no NODE_NETWORK)\n", ToString(you).c_str());
-        ban = 1000000;
-        return true;
-      }
-      
       if (nVersion >= 209) {
         BeginMessage("verack");
         EndMessage();
@@ -204,7 +192,7 @@ class CNode {
   }
   
 public:
-  CNode(const CIPPort& ip, vector<CAddress>& vAddrIn) : you(ip), nHeaderStart(-1), nMessageStart(-1), vAddr(&vAddrIn), ban(0), doneAfter(0) {
+  CNode(const CIPPort& ip, vector<CAddress>& vAddrIn) : you(ip), nHeaderStart(-1), nMessageStart(-1), vAddr(&vAddrIn), ban(0), doneAfter(0), nVersion(0) {
     vSend.SetType(SER_NETWORK);
     vSend.SetVersion(0);
     vRecv.SetType(SER_NETWORK);
@@ -264,9 +252,13 @@ public:
   int GetBan() {
     return ban;
   }
+  
+  int GetClientVersion() {
+    return nVersion;
+  }
 };
 
-bool TestNode(const CIPPort &cip, int &ban, vector<CAddress>& vAddr) {
+bool TestNode(const CIPPort &cip, int &ban, int &clientV, vector<CAddress>& vAddr) {
   CNode node(cip, vAddr);
   bool ret = node.Run();
   if (!ret) {
@@ -274,6 +266,7 @@ bool TestNode(const CIPPort &cip, int &ban, vector<CAddress>& vAddr) {
   } else {
     ban = 0;
   }
+  clientV = node.GetClientVersion();
 //  printf("%s: %s!!!\n", cip.ToString().c_str(), ret ? "GOOD" : "BAD");
   return ret;
 }
diff --git a/bitcoin.h b/bitcoin.h
index 4f6f766..04f3c07 100644
--- a/bitcoin.h
+++ b/bitcoin.h
@@ -3,6 +3,6 @@
 
 #include "protocol.h"
 
-bool TestNode(const CIPPort &cip, int &ban, std::vector<CAddress>& vAddr);
+bool TestNode(const CIPPort &cip, int &ban, int &client, std::vector<CAddress>& vAddr);
 
 #endif
diff --git a/db.cpp b/db.cpp
index 526e779..5b111b0 100644
--- a/db.cpp
+++ b/db.cpp
@@ -4,48 +4,75 @@
 using namespace std;
 
 void CAddrInfo::Update(bool good) {
-    uint32_t now = time(NULL);
-    if (ourLastTry == 0)
-      ourLastTry = now - MIN_RETRY;
-    lastTry = now;
-    ourLastTry = now;
-    total++;
-    if (good) success++;
-    printf("%s: got %s result: weight=%g reliability=%g avgage=%g count=%g success=%i/%i\n", ToString(ip).c_str(), good ? "good" : "bad", weight, GetReliability(), GetAvgAge(), GetCount(), success, total);
+  uint32_t now = time(NULL);
+  if (ourLastTry == 0)
+    ourLastTry = now - MIN_RETRY;
+  int age = now - ourLastTry;
+  lastTry = now;
+  ourLastTry = now;
+  total++;
+  if (good) success++;
+  stat2H.Update(good, age, 3600*2);
+  stat8H.Update(good, age, 3600*8);
+  stat1D.Update(good, age, 3600*24);
+  stat1W.Update(good, age, 3600*24*7);
+  int ign = GetIgnoreTime();
+  if (ign && (ignoreTill==0 || ignoreTill < ign+now)) ignoreTill = ign+now;
+  printf("%s: got %s result: success=%i/%i; 2H:%.2f%%-%.2f%%(%.2f) 8H:%.2f%%-%.2f%%(%.2f) 1D:%.2f%%-%.2f%%(%.2f) 1W:%.2f%%-%.2f%%(%.2f) \n", ToString(ip).c_str(), good ? "good" : "bad", success, total, 
+  100.0 * stat2H.reliability, 100.0 * (stat2H.reliability + 1.0 - stat2H.weight), stat2H.count,
+  100.0 * stat8H.reliability, 100.0 * (stat8H.reliability + 1.0 - stat8H.weight), stat8H.count,
+  100.0 * stat1D.reliability, 100.0 * (stat1D.reliability + 1.0 - stat1D.weight), stat1D.count,
+  100.0 * stat1W.reliability, 100.0 * (stat1W.reliability + 1.0 - stat1W.weight), stat1W.count);
 }
 
 bool CAddrDb::Get_(CIPPort &ip, int &wait) {
   int64 now = time(NULL);
+  int cont = 0;
   int tot = unkId.size();
-  deque<int>::iterator it = ourId.begin();
-  while (it < ourId.end()) {
-    if (now - idToInfo[*it].ourLastTry > MIN_RETRY) {
-      tot++;
-      it++;
+  do {
+    deque<int>::iterator it = ourId.begin();
+    while (it < ourId.end()) {
+      if (now - idToInfo[*it].ourLastTry > MIN_RETRY) {
+        tot++;
+        it++;
+      } else {
+        break;
+      }
+    }
+    if (tot == 0) {
+      if (ourId.size() > 0) {
+        wait = MIN_RETRY - (now - idToInfo[ourId.front()].ourLastTry);
+      } else {
+        wait = 5;
+      }
+      return false;
+    }
+    int rnd = rand() % tot;
+    int ret;
+    if (rnd < unkId.size()) {
+      if (rnd*10 < unkId.size()) {
+        // once every 10 attempts, restart with the oldest unknown IP
+        set<int>::iterator it = unkId.begin();
+        ret = *it;
+      } else {
+        // 90% of the time try the last learned IP
+        set<int>::reverse_iterator it = unkId.rbegin();
+        ret = *it;
+      }
+      unkId.erase(ret);
     } else {
-      break;
+      int ret = ourId.front();
+      if (time(NULL) - idToInfo[ret].ourLastTry < MIN_RETRY) return false;
+      ourId.pop_front();
     }
-  }
-  if (tot == 0) {
-    if (ourId.size() > 0) {
-      wait = MIN_RETRY - (now - idToInfo[ourId.front()].ourLastTry);
+    if (idToInfo[ret].ignoreTill && idToInfo[ret].ignoreTill < now) {
+      ourId.push_back(ret);
+    } else {
+      ip = idToInfo[ret].ip;
+      break;
     }
-    return false;
-  }
-  int rnd = rand() % tot;
-  if (rnd < unkId.size()) {
-    set<int>::reverse_iterator it = unkId.rbegin();
-    ip = idToInfo[*it].ip;
-    unkId.erase(*it);
-    printf("%s: new node\n", ToString(ip).c_str());
-  } else {
-    int ret = ourId.front();
-    if (time(NULL) - idToInfo[ret].ourLastTry < MIN_RETRY) return false;
-    ourId.pop_front();
-    ip = idToInfo[ret].ip;
-    printf("%s: old node\n", ToString(ip).c_str());
-  }
-  fDirty = true;
+  } while(1);
+  nDirty++;
   return true;
 }
 
@@ -55,18 +82,19 @@ int CAddrDb::Lookup_(const CIPPort &ip) {
   return -1;
 }
 
-void CAddrDb::Good_(const CIPPort &addr) {
+void CAddrDb::Good_(const CIPPort &addr, int clientV) {
   int id = Lookup_(addr);
   if (id == -1) return;
   unkId.erase(id);
   banned.erase(addr);
   CAddrInfo &info = idToInfo[id];
+  info.clientVersion = clientV;
   info.Update(true);
   if (info.IsGood() && goodId.count(id)==0) {
     goodId.insert(id);
     printf("%s: good; %i good nodes now\n", ToString(addr).c_str(), (int)goodId.size());
   }
-  fDirty = true;
+  nDirty++;
   ourId.push_back(id);
 }
 
@@ -78,9 +106,10 @@ void CAddrDb::Bad_(const CIPPort &addr, int ban)
   CAddrInfo &info = idToInfo[id];
   info.Update(false);
   uint32_t now = time(NULL);
-  if (info.IsTerrible()) {
+  int ter = info.GetBanTime();
+  if (ter) {
     printf("%s: terrible\n", ToString(addr).c_str());
-    if (ban < 604800) ban = 604800;
+    if (ban < ter) ban = ter;
   }
   if (ban > 0) {
     printf("%s: ban for %i seconds\n", ToString(addr).c_str(), ban);
@@ -95,7 +124,7 @@ void CAddrDb::Bad_(const CIPPort &addr, int ban)
     }
     ourId.push_back(id);
   }
-  fDirty = true;
+  nDirty++;
 }
 
 void CAddrDb::Skipped_(const CIPPort &addr)
@@ -105,7 +134,7 @@ void CAddrDb::Skipped_(const CIPPort &addr)
   unkId.erase(id);
   ourId.push_back(id);
   printf("%s: skipped\n", ToString(addr).c_str());
-  fDirty = true;
+  nDirty++;
 }
 
 
@@ -135,8 +164,6 @@ void CAddrDb::Add_(const CAddress &addr) {
   ai.services = addr.nServices;
   ai.lastTry = addr.nTime;
   ai.ourLastTry = 0;
-  ai.reliability = 0;
-  ai.weight = 0;
   ai.total = 0;
   ai.success = 0;
   int id = nId++;
@@ -144,7 +171,7 @@ void CAddrDb::Add_(const CAddress &addr) {
   ipToId[ipp] = id;
   printf("%s: added\n", ToString(ipp).c_str(), ipToId[ipp]);
   unkId.insert(id);
-  fDirty = true;
+  nDirty++;
 }
 
 void CAddrDb::GetIPs_(set<CIP>& ips, int max, bool fOnlyIPv4) {
diff --git a/db.h b/db.h
index 6ad869d..c85c5ae 100644
--- a/db.h
+++ b/db.h
@@ -10,7 +10,6 @@
 #include "protocol.h"
 #include "util.h"
 
-#define TAU 86400.0
 #define MIN_RETRY 1000
 
 std::string static inline ToString(const CIPPort &ip) {
@@ -19,17 +18,29 @@ std::string static inline ToString(const CIPPort &ip) {
   return str;
 }
 
-template<float tau> class CAddrStat {
+class CAddrStat {
 private:
-  float reliability;
-  float timing;
-  float count;
   float weight;
+  float count;
+  float reliability;
 public:
-  void Update(bool good, int64 tim) {
-    
+  CAddrStat() : weight(0), count(0), reliability(0) {}
+
+  void Update(bool good, int64 age, double tau) {
+    double f =  exp(-age/tau);
+    reliability = reliability * f + (good ? (1.0-f) : 0);
+    count = count * f + 1;
+    weight = weight * f + (1.0-f);
   }
-}
+  
+  IMPLEMENT_SERIALIZE (
+    READWRITE(weight);
+    READWRITE(count);
+    READWRITE(reliability);
+  )
+
+  friend class CAddrInfo;
+};
 
 class CAddrInfo {
 private:
@@ -37,39 +48,67 @@ private:
   uint64_t services;
   int64 lastTry;
   int64 ourLastTry;
-  double reliability;
-  double timing;
-  double weight;
-  double count;
+  int64 ignoreTill;
+  CAddrStat stat2H;
+  CAddrStat stat8H;
+  CAddrStat stat1D;
+  CAddrStat stat1W;
+  int clientVersion;
   int total;
   int success;
 public:
-  double GetCount() const { return count; }
-  double GetAvgAge() const { return timing/weight; }
-  double GetReliability() const { return reliability/weight; }
+  CAddrInfo() : services(0), lastTry(0), ourLastTry(0), ignoreTill(0), clientVersion(0), total(0), success(0) {}
+  
   bool IsGood() {
-    return (weight > 0 && GetReliability() > 0.8 && GetAvgAge() < 86400 && ip.GetPort() == 8333 && ip.IsRoutable());
+    if (ip.GetPort() != 8333) return false;
+    if (!(services & NODE_NETWORK)) return false;
+    if (!ip.IsRoutable()) return false;
+    if (!ip.IsIPv4()) return false;
+    if (clientVersion && clientVersion < 32400) return false;
+
+    if (total <= 3 && success * 2 >= total) return true;
+
+    if (stat2H.reliability > 0.7 && stat2H.count > 3) return true;
+    if (stat8H.reliability > 0.6 && stat8H.count > 6) return true;
+    if (stat1D.reliability > 0.5 && stat1D.count > 12) return true;
+    if (stat1W.reliability > 0.4 && stat1W.count > 24) return true;
+    
+    return false;
+  }
+  int GetBanTime() {
+    if (IsGood()) return 0;
+    if (clientVersion && clientVersion < 31900) { return 1000000; }
+    if (stat1D.reliability < 0.01 && stat1D.count > 5) { return 500000; }
+    if (stat1W.reliability - stat1W.weight + 1.0 < 0.10 && stat1W.count > 4) { return 240*3600; }
+    return 0;
   }
-  bool IsTerrible() {
-    return ((weight > 0.1 && GetCount() > 5 && GetReliability() < 0.05) || (weight > 0.5 && GetReliability() < 0.2 && GetAvgAge() > 7200 && GetCount() > 5));
+  int GetIgnoreTime() {
+    if (IsGood()) return 0;
+    if (stat2H.reliability - stat2H.weight + 1.0 < 0.2 && stat2H.count > 3) { return 3*3600; }
+    if (stat8H.reliability - stat8H.weight + 1.0 < 0.2 && stat8H.count > 6) { return 12*3600; }
+    if (stat1D.reliability - stat1D.weight + 1.0 < 0.2 && stat1D.count > 9) { return 36*3600; }
+    return 0;
   }
+  
   void Update(bool good);
   
   friend class CAddrDb;
   
   IMPLEMENT_SERIALIZE (
-    int version = 0;
+    unsigned char version = 0;
     READWRITE(version);
     READWRITE(ip);
     READWRITE(services);
     READWRITE(lastTry);
     READWRITE(ourLastTry);
-    READWRITE(reliability);
-    READWRITE(timing);
-    READWRITE(weight);
-    READWRITE(count);
+    READWRITE(ignoreTill);
+    READWRITE(stat2H);
+    READWRITE(stat8H);
+    READWRITE(stat1D);
+    READWRITE(stat1W);
     READWRITE(total);
     READWRITE(success);
+    READWRITE(clientVersion);
   )
 };
 
@@ -91,13 +130,13 @@ private:
   std::set<int> unkId; // set of nodes not yet tried (b)
   std::set<int> goodId; // set of good nodes  (d, good e)
   std::map<CIPPort, time_t> banned; // nodes that are banned, with their unban time (a)
-  bool fDirty;
+  int nDirty;
   
 protected:
   // internal routines that assume proper locks are acquired
   void Add_(const CAddress &addr);        // add an address
   bool Get_(CIPPort &ip, int& wait);      // get an IP to test (must call Good_, Bad_, or Skipped_ on result afterwards)
-  void Good_(const CIPPort &ip);          // mark an IP as good (must have been returned by Get_)
+  void Good_(const CIPPort &ip, int clientV); // mark an IP as good (must have been returned by Get_)
   void Bad_(const CIPPort &ip, int ban);  // mark an IP as bad (and optionally ban it) (must have been returned by Get_)
   void Skipped_(const CIPPort &ip);       // mark an IP as skipped (must have been returned by Get_)
   int Lookup_(const CIPPort &ip);         // look up id of an IP
@@ -105,13 +144,11 @@ protected:
 
 public:
 
-  // seriazlization code
+  // serialization code
   // format:
   //   nVersion (0 for now)
-  //   nOur (number of ips in (c,d))
-  //   nUnk (number of ips in (b))
-  //   CAddrInfo[nOur]
-  //   CAddrInfo[nUnk]
+  //   n (number of ips in (b,c,d))
+  //   CAddrInfo[n]
   //   banned
   // acquires a shared lock (this does not suffice for read mode, but we assume that only happens at startup, single-threaded)
   // this way, dumping does not interfere with GetIPs_, which is called from the DNS thread
@@ -121,10 +158,8 @@ public:
     SHARED_CRITICAL_BLOCK(cs) {
       if (fWrite) {
         CAddrDb *db = const_cast<CAddrDb*>(this);
-        int nOur = ourId.size();
-        int nUnk = unkId.size();
-        READWRITE(nOur);
-        READWRITE(nUnk);
+        int n = ourId.size() + unkId.size();
+        READWRITE(n);
         for (std::deque<int>::const_iterator it = ourId.begin(); it != ourId.end(); it++) {
           std::map<int, CAddrInfo>::iterator ci = db->idToInfo.find(*it);
           READWRITE((*ci).second);
@@ -136,31 +171,24 @@ public:
       } else {
         CAddrDb *db = const_cast<CAddrDb*>(this);
         db->nId = 0;
-        int nOur, nUnk;
-        READWRITE(nOur);
-        READWRITE(nUnk);
-        for (int i=0; i<nOur; i++) {
-          CAddrInfo info;
-          READWRITE(info);
-          if (!info.IsTerrible()) {
-            int id = db->nId++;
-            db->idToInfo[id] = info;
-            db->ipToId[info.ip] = id;
-            db->ourId.push_back(id);
-            if (info.IsGood()) db->goodId.insert(id);
-          }
-        }
-        for (int i=0; i<nUnk; i++) {
+        int n;
+        READWRITE(n);
+        for (int i=0; i<n; i++) {
           CAddrInfo info;
           READWRITE(info);
-          if (!info.IsTerrible()) {
+          if (!info.GetBanTime()) {
             int id = db->nId++;
             db->idToInfo[id] = info;
             db->ipToId[info.ip] = id;
-            db->unkId.insert(id);
+            if (info.ourLastTry) {
+              db->ourId.push_back(id);
+              if (info.IsGood()) db->goodId.insert(id);
+            } else {
+              db->unkId.insert(id);
+            }
           }
         }
-        db->fDirty = true;
+        db->nDirty++;
       }
       READWRITE(banned);
     }
@@ -169,7 +197,7 @@ public:
   // print statistics
   void Stats() {
     SHARED_CRITICAL_BLOCK(cs) {
-      if (fDirty) {
+      if (nDirty > 50) {
         printf("**** %i available (%i tracked, %i new, %i active), %i banned; %i good\n", 
                (int)idToInfo.size(),
                (int)ourId.size(),
@@ -177,7 +205,7 @@ public:
                (int)idToInfo.size() - (int)ourId.size() - (int)unkId.size(),
                (int)banned.size(),
                (int)goodId.size());
-        fDirty = false; // hopefully atomic
+        nDirty = 0; // hopefully atomic
       }
     }
   }
@@ -190,9 +218,9 @@ public:
       for (int i=0; i<vAddr.size(); i++)
         Add_(vAddr[i]);
   }
-  void Good(const CIPPort &addr) {
+  void Good(const CIPPort &addr, int clientVersion) {
     CRITICAL_BLOCK(cs)
-      Good_(addr);
+      Good_(addr, clientVersion);
   }
   void Skipped(const CIPPort &addr) {
     CRITICAL_BLOCK(cs)
diff --git a/main.cpp b/main.cpp
index 2fa4d1f..5e1216f 100644
--- a/main.cpp
+++ b/main.cpp
@@ -3,7 +3,7 @@
 #include "bitcoin.h"
 #include "db.h"
 
-#define NTHREADS 100
+#define NTHREADS 16
 
 using namespace std;
 
@@ -26,10 +26,11 @@ extern "C" void* ThreadCrawler(void* data) {
     }
     int ban = 0;
     vector<CAddress> addr;
-    bool ret = TestNode(ip,ban,addr);
+    int clientV = 0;
+    bool ret = TestNode(ip,ban,clientV,addr);
     db.Add(addr);
     if (ret) {
-      db.Good(ip);
+      db.Good(ip, clientV);
     } else {
       db.Bad(ip, ban);
     }
@@ -81,8 +82,6 @@ extern "C" void* ThreadDumper(void*) {
   } while(1);
 }
 
-#define NTHREADS 100
-
 int main(void) {
   FILE *f = fopen("dnsseed.dat","r");
   if (f) {
diff --git a/netbase.cpp b/netbase.cpp
index b8680df..9976c10 100644
--- a/netbase.cpp
+++ b/netbase.cpp
@@ -224,7 +224,7 @@ bool CIPPort::ConnectSocket(SOCKET& hSocketRet, int nTimeout) const
             }
             if (nRet == SOCKET_ERROR)
             {
-                printf("select() for connection failed: %i\n",WSAGetLastError());
+                printf("select() for connection failed: %s\n",strerror(WSAGetLastError()));
                 closesocket(hSocket);
                 return false;
             }
@@ -235,7 +235,7 @@ bool CIPPort::ConnectSocket(SOCKET& hSocketRet, int nTimeout) const
             if (getsockopt(hSocket, SOL_SOCKET, SO_ERROR, &nRet, &nRetSize) == SOCKET_ERROR)
 #endif
             {
-                printf("getsockopt() for connection failed: %i\n",WSAGetLastError());
+                printf("getsockopt() for connection failed: %s\n",strerror(WSAGetLastError()));
                 closesocket(hSocket);
                 return false;
             }