diff --git a/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/ui/GeneralHelper.java b/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/ui/GeneralHelper.java
index c09f226e1c..83c7fca4bb 100644
--- a/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/ui/GeneralHelper.java
+++ b/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/ui/GeneralHelper.java
@@ -504,6 +504,8 @@ public class GeneralHelper {
 
     /**
      *  @param newTunnelType used if tunnel < 0
+     *  @return the current type if we have a destination already,
+     *          else the default for that type of tunnel
      */
     public int getSigType(int tunnel, String newTunnelType) {
         SigType type;
diff --git a/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/web/EditBean.java b/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/web/EditBean.java
index 6e63732260..bacd84aea8 100644
--- a/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/web/EditBean.java
+++ b/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/web/EditBean.java
@@ -23,6 +23,7 @@ import net.i2p.data.Signature;
 import net.i2p.data.SigningPrivateKey;
 import net.i2p.i2ptunnel.TunnelController;
 import net.i2p.i2ptunnel.TunnelControllerGroup;
+import net.i2p.i2ptunnel.ui.GeneralHelper;
 import net.i2p.util.Addresses;
 
 /**
@@ -222,7 +223,16 @@ public class EditBean extends IndexBean {
     public boolean isSigTypeAvailable(int code) {
         return SigType.isAvailable(code);
     }
-    
+
+    /** @since 0.9.33 */
+    public boolean canChangeSigType(int tunnel) {
+        if (tunnel < 0)
+            return true;
+        if (getDestination(tunnel) != null)
+            return false;
+        return getTunnelStatus(tunnel) == GeneralHelper.NOT_RUNNING;
+    }
+
     /**
      *  Random keys, hidden in forms
      *  @since 0.9.18
diff --git a/apps/i2ptunnel/jsp/editClient.jsi b/apps/i2ptunnel/jsp/editClient.jsi
index 8e5e92b535..88a9a89704 100644
--- a/apps/i2ptunnel/jsp/editClient.jsi
+++ b/apps/i2ptunnel/jsp/editClient.jsi
@@ -116,7 +116,7 @@
             <td>
                 <b><%=intl._t("Reachable by")%>:</b>
 
-                <select id="reachableBy" name="reachableBy" title="<%=intl._t("Local interface (ip address) the client tunnel will be reachable from")%>" class="selectbox")%>">
+                <select id="reachableBy" name="reachableBy" title="<%=intl._t("Local interface (ip address) the client tunnel will be reachable from")%>" class="selectbox">
               <%
                     String clientInterface = editBean.getClientInterface(curTunnel);
                     for (String ifc : editBean.interfaceSet()) {
@@ -544,24 +544,25 @@
 
          <% if (true /* editBean.isAdvanced() */ ) {
                 int currentSigType = editBean.getSigType(curTunnel, tunnelType);
+                String disabled = editBean.canChangeSigType(curTunnel) ? "" : " disabled=\"disabled\" ";
            %>
         <tr>
             <th colspan="2">
-                <%=intl._t("Signature type")%> (<%=intl._t("Experts only!")%>)
+                <%=intl._t("Signature type")%> <%-- (<%=intl._t("Experts only!")%>) --%>
             </th>
         </tr>
 
         <tr>
             <td colspan="2">
                 <span class="multiOption">
-                    <label title="<%=intl._t("Legacy option (deprecated), provided for backward compatibility")%>"><input value="0" type="radio" name="sigType"<%=(currentSigType==0 ? " checked=\"checked\"" : "")%> class="tickbox" />
+                    <label title="<%=intl._t("Legacy option (deprecated), provided for backward compatibility")%>"><input value="0" type="radio" name="sigType" <%=disabled%> <%=(currentSigType==0 ? " checked=\"checked\"" : "")%> class="tickbox" />
                     DSA-SHA1</label>
                 </span>
 
            <% if (editBean.isSigTypeAvailable(1)) { %>
 
                 <span class="multiOption">
-                    <label><input value="1" type="radio" name="sigType"<%=(currentSigType==1 ? " checked=\"checked\"" : "")%> class="tickbox" />
+                    <label><input value="1" type="radio" name="sigType" <%=disabled%> <%=(currentSigType==1 ? " checked=\"checked\"" : "")%> class="tickbox" />
                     ECDSA-P256</label>
                 </span>
 
@@ -570,7 +571,7 @@
               if (editBean.isSigTypeAvailable(2)) { %>
 
                 <span class="multiOption">
-                    <label><input value="2" type="radio" name="sigType"<%=(currentSigType==2 ? " checked=\"checked\"" : "")%> class="tickbox" />
+                    <label><input value="2" type="radio" name="sigType" <%=disabled%> <%=(currentSigType==2 ? " checked=\"checked\"" : "")%> class="tickbox" />
                     ECDSA-P384</label>
                 </span>
 
@@ -578,7 +579,7 @@
               if (editBean.isSigTypeAvailable(3)) { %>
 
                 <span class="multiOption">
-                    <label><input value="3" type="radio" name="sigType"<%=(currentSigType==3 ? " checked=\"checked\"" : "")%> class="tickbox" />
+                    <label><input value="3" type="radio" name="sigType" <%=disabled%> <%=(currentSigType==3 ? " checked=\"checked\"" : "")%> class="tickbox" />
                     ECDSA-P521</label>
                 </span>
 
@@ -586,7 +587,7 @@
               if (editBean.isSigTypeAvailable(7)) { %>
 
                 <span class="multiOption">
-                    <label title="<%=intl._t("This is the default, recommended option")%>"><input value="7" type="radio" name="sigType"<%=(currentSigType==7 ? " checked=\"checked\"" : "")%> class="tickbox" />
+                    <label title="<%=intl._t("This is the default, recommended option")%>"><input value="7" type="radio" name="sigType" <%=disabled%> <%=(currentSigType==7 ? " checked=\"checked\"" : "")%> class="tickbox" />
                     Ed25519-SHA-512</label>
                 </span>
             </td>
diff --git a/apps/i2ptunnel/jsp/editServer.jsi b/apps/i2ptunnel/jsp/editServer.jsi
index 1a0f5cb4c0..e0aeb0ee7d 100644
--- a/apps/i2ptunnel/jsp/editServer.jsi
+++ b/apps/i2ptunnel/jsp/editServer.jsi
@@ -792,39 +792,40 @@
          <%
             int currentSigType = editBean.getSigType(curTunnel, tunnelType);
             if (true /* editBean.isAdvanced() */ ) {
+                String disabled = editBean.canChangeSigType(curTunnel) ? "" : " disabled=\"disabled\" ";
            %>
         <tr>
             <th colspan="2">
-                <%=intl._t("Signature type")%> (<%=intl._t("Experts only! Changes B32!")%>)
+                <%=intl._t("Signature type")%> <%-- (<%=intl._t("Experts only! Changes B32!")%>) --%>
             </th>
         </tr>
         <tr>
             <td colspan="2">
                 <span class="multiOption">
-                    <label title="<%=intl._t("Legacy option (deprecated), provided for backward compatibility")%>"><input value="0" type="radio" id="startOnLoad" name="sigType"<%=(currentSigType==0 ? " checked=\"checked\"" : "")%> class="tickbox" />
+                    <label title="<%=intl._t("Legacy option (deprecated), provided for backward compatibility")%>"><input value="0" type="radio" id="startOnLoad" name="sigType" <%=disabled%> <%=(currentSigType==0 ? " checked=\"checked\"" : "")%> class="tickbox" />
                     DSA-SHA1</label>
                 </span>
            <% if (editBean.isSigTypeAvailable(1)) { %>
                 <span class="multiOption">
-                    <label><input value="1" type="radio" id="startOnLoad" name="sigType"<%=(currentSigType==1 ? " checked=\"checked\"" : "")%> class="tickbox" />
+                    <label><input value="1" type="radio" id="startOnLoad" name="sigType" <%=disabled%> <%=(currentSigType==1 ? " checked=\"checked\"" : "")%> class="tickbox" />
                     ECDSA-P256</label>
                 </span>
            <% }
               if (editBean.isSigTypeAvailable(2)) { %>
                 <span class="multiOption">
-                    <label><input value="2" type="radio" id="startOnLoad" name="sigType"<%=(currentSigType==2 ? " checked=\"checked\"" : "")%> class="tickbox" />
+                    <label><input value="2" type="radio" id="startOnLoad" name="sigType" <%=disabled%> <%=(currentSigType==2 ? " checked=\"checked\"" : "")%> class="tickbox" />
                     ECDSA-P384</label>
                 </span>
            <% }
               if (editBean.isSigTypeAvailable(3)) { %>
                 <span class="multiOption">
-                    <label><input value="3" type="radio" id="startOnLoad" name="sigType"<%=(currentSigType==3 ? " checked=\"checked\"" : "")%> class="tickbox" />
+                    <label><input value="3" type="radio" id="startOnLoad" name="sigType" <%=disabled%> <%=(currentSigType==3 ? " checked=\"checked\"" : "")%> class="tickbox" />
                     ECDSA-P521</label>
                 </span>
            <% }
               if (editBean.isSigTypeAvailable(7)) { %>
                 <span class="multiOption">
-                    <label title="<%=intl._t("This is the default, recommended option")%>"><input value="7" type="radio" id="startOnLoad" name="sigType"<%=(currentSigType==7 ? " checked=\"checked\"" : "")%> class="tickbox" />
+                    <label title="<%=intl._t("This is the default, recommended option")%>"><input value="7" type="radio" id="startOnLoad" name="sigType" <%=disabled%> <%=(currentSigType==7 ? " checked=\"checked\"" : "")%> class="tickbox" />
                     Ed25519-SHA-512</label>
                 </span>
            <% }   // isAvailable %>
diff --git a/history.txt b/history.txt
index e4b8963892..cf5fb47fd4 100644
--- a/history.txt
+++ b/history.txt
@@ -1,3 +1,10 @@
+2018-01-19 zzz
+ * i2ptunnel: Prevent changing sigtype after dest creation (ticket #2128)
+
+2018-01-18 zzz
+ * Build: New poupdate-source target
+ * Util: Consolidate console URL generation in PortMapper
+
 2018-01-17 zzz
  * i2ptunnel:
    - Set defaults for limits
diff --git a/router/java/src/net/i2p/router/RouterVersion.java b/router/java/src/net/i2p/router/RouterVersion.java
index 9319fc01c9..9535f12e9f 100644
--- a/router/java/src/net/i2p/router/RouterVersion.java
+++ b/router/java/src/net/i2p/router/RouterVersion.java
@@ -18,10 +18,10 @@ public class RouterVersion {
     /** deprecated */
     public final static String ID = "Monotone";
     public final static String VERSION = CoreVersion.VERSION;
-    public final static long BUILD = 22;
+    public final static long BUILD = 23;
 
     /** for example "-test" */
-    public final static String EXTRA = "";
+    public final static String EXTRA = "-rc";
     public final static String FULL_VERSION = VERSION + "-" + BUILD + EXTRA;
     public static void main(String args[]) {
         System.out.println("I2P Router version: " + FULL_VERSION);