diff --git a/domain/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/domain/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index d7d8980..1e4e905 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -40,6 +40,7 @@ import static ch.dissem.bitmessage.entity.Plaintext.Status.*;
 import static ch.dissem.bitmessage.entity.Plaintext.Type.BROADCAST;
 import static ch.dissem.bitmessage.entity.Plaintext.Type.MSG;
 import static ch.dissem.bitmessage.utils.UnixTime.DAY;
+import static ch.dissem.bitmessage.utils.UnixTime.HOUR;
 
 /**
  * <p>Use this class if you want to create a Bitmessage client.</p>
@@ -295,6 +296,8 @@ public class BitmessageContext {
         Security security;
         MessageCallback messageCallback;
         Listener listener;
+        int connectionLimit = 150;
+        long connectionTTL = 12 * HOUR;
 
         public Builder() {
         }
@@ -349,6 +352,16 @@ public class BitmessageContext {
             return this;
         }
 
+        public Builder connectionLimit(int connectionLimit) {
+            this.connectionLimit = connectionLimit;
+            return this;
+        }
+
+        public Builder connectionTTL(int hours) {
+            this.connectionTTL = hours * HOUR;
+            return this;
+        }
+
         public BitmessageContext build() {
             nonNull("inventory", inventory);
             nonNull("nodeRegistry", nodeRegistry);
diff --git a/domain/src/main/java/ch/dissem/bitmessage/InternalContext.java b/domain/src/main/java/ch/dissem/bitmessage/InternalContext.java
index 6d969bd..bbdedb6 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/InternalContext.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/InternalContext.java
@@ -56,6 +56,8 @@ public class InternalContext {
     private final long clientNonce;
     private final long networkNonceTrialsPerByte = 1000;
     private final long networkExtraBytes = 1000;
+    private long connectionTTL;
+    private int connectionLimit;
 
     public InternalContext(BitmessageContext.Builder builder) {
         this.security = builder.security;
@@ -68,6 +70,8 @@ public class InternalContext {
         this.clientNonce = security.randomNonce();
         this.messageCallback = builder.messageCallback;
         this.port = builder.port;
+        this.connectionLimit = builder.connectionLimit;
+        this.connectionTTL = builder.connectionTTL;
 
         Singleton.initialize(security);
 
@@ -166,7 +170,7 @@ public class InternalContext {
                     .payload(payload)
                     .build();
             if (object.isSigned()) {
-                object.sign( from.getPrivateKey());
+                object.sign(from.getPrivateKey());
             }
             if (payload instanceof Broadcast) {
                 ((Broadcast) payload).encrypt();
@@ -232,6 +236,14 @@ public class InternalContext {
         return clientNonce;
     }
 
+    public long getConnectionTTL() {
+        return connectionTTL;
+    }
+
+    public int getConnectionLimit() {
+        return connectionLimit;
+    }
+
     public interface ContextHolder {
         void setContext(InternalContext context);
     }
diff --git a/domain/src/main/java/ch/dissem/bitmessage/utils/Singleton.java b/domain/src/main/java/ch/dissem/bitmessage/utils/Singleton.java
index 169db77..d272beb 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/utils/Singleton.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/utils/Singleton.java
@@ -25,7 +25,11 @@ public class Singleton {
     private static Security security;
 
     public static void initialize(Security security) {
-        Singleton.security = security;
+        synchronized (Singleton.class) {
+            if (Singleton.security == null) {
+                Singleton.security = security;
+            }
+        }
     }
 
     public static Security security() {
diff --git a/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java b/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java
index 6312557..f0ff5ed 100644
--- a/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java
+++ b/networking/src/main/java/ch/dissem/bitmessage/networking/Connection.java
@@ -51,8 +51,10 @@ import static ch.dissem.bitmessage.utils.UnixTime.MINUTE;
  */
 public class Connection {
     public static final int READ_TIMEOUT = 2000;
-    private final static Logger LOG = LoggerFactory.getLogger(Connection.class);
+    private static final Logger LOG = LoggerFactory.getLogger(Connection.class);
     private static final int CONNECT_TIMEOUT = 5000;
+
+    private final long startTime;
     private final ConcurrentMap<InventoryVector, Long> ivCache;
     private final InternalContext ctx;
     private final Mode mode;
@@ -89,6 +91,7 @@ public class Connection {
 
     private Connection(InternalContext context, Mode mode, MessageListener listener, Socket socket,
                        Map<InventoryVector, Long> requestedObjectsMap, NetworkAddress node, long syncTimeout) {
+        this.startTime = UnixTime.now();
         this.ctx = context;
         this.mode = mode;
         this.state = CONNECTING;
@@ -109,6 +112,10 @@ public class Connection {
                 timeoutInSeconds);
     }
 
+    public long getStartTime() {
+        return startTime;
+    }
+
     public Mode getMode() {
         return mode;
     }
diff --git a/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java b/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java
index e563152..7b49978 100644
--- a/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java
+++ b/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java
@@ -23,6 +23,7 @@ import ch.dissem.bitmessage.entity.valueobject.NetworkAddress;
 import ch.dissem.bitmessage.ports.NetworkHandler;
 import ch.dissem.bitmessage.utils.Collections;
 import ch.dissem.bitmessage.utils.Property;
+import ch.dissem.bitmessage.utils.UnixTime;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -112,9 +113,21 @@ public class DefaultNetworkHandler implements NetworkHandler, ContextHolder {
                         while (running) {
                             try {
                                 int active = 0;
+                                long now = UnixTime.now();
                                 synchronized (connections) {
+                                    int diff = connections.size() - ctx.getConnectionLimit();
+                                    if (diff > 0) {
+                                        for (Connection c : connections) {
+                                            c.disconnect();
+                                            diff--;
+                                            if (diff == 0) break;
+                                        }
+                                    }
                                     for (Iterator<Connection> iterator = connections.iterator(); iterator.hasNext(); ) {
                                         Connection c = iterator.next();
+                                        if (now - c.getStartTime() > ctx.getConnectionTTL()) {
+                                            c.disconnect();
+                                        }
                                         if (c.getState() == DISCONNECTED) {
                                             // Remove the current element from the iterator and the list.
                                             iterator.remove();