diff --git a/pkg/registry/core/service/portallocator/allocator.go b/pkg/registry/core/service/portallocator/allocator.go
index 8e3d42be08..e088bc91a5 100644
--- a/pkg/registry/core/service/portallocator/allocator.go
+++ b/pkg/registry/core/service/portallocator/allocator.go
@@ -33,6 +33,7 @@ type Interface interface {
 	Allocate(int) error
 	AllocateNext() (int, error)
 	Release(int) error
+	ForEach(func(int))
 }
 
 var (
@@ -117,6 +118,13 @@ func (r *PortAllocator) AllocateNext() (int, error) {
 	return r.portRange.Base + offset, nil
 }
 
+// ForEach calls the provided function for each allocated port.
+func (r *PortAllocator) ForEach(fn func(int)) {
+	r.alloc.ForEach(func(offset int) {
+		fn(r.portRange.Base + offset)
+	})
+}
+
 // Release releases the port back to the pool. Releasing an
 // unallocated port or a port out of the range is a no-op and
 // returns no error.
diff --git a/pkg/registry/core/service/portallocator/allocator_test.go b/pkg/registry/core/service/portallocator/allocator_test.go
index 7386172b5e..8250112042 100644
--- a/pkg/registry/core/service/portallocator/allocator_test.go
+++ b/pkg/registry/core/service/portallocator/allocator_test.go
@@ -103,6 +103,44 @@ func TestAllocate(t *testing.T) {
 	}
 }
 
+func TestForEach(t *testing.T) {
+	pr, err := net.ParsePortRange("10000-10200")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	testCases := []sets.Int{
+		sets.NewInt(),
+		sets.NewInt(10000),
+		sets.NewInt(10000, 10200),
+		sets.NewInt(10000, 10099, 10200),
+	}
+
+	for i, tc := range testCases {
+		r := NewPortAllocator(*pr)
+
+		for port := range tc {
+			if err := r.Allocate(port); err != nil {
+				t.Errorf("[%d] error allocating port %v: %v", i, port, err)
+			}
+			if !r.Has(port) {
+				t.Errorf("[%d] expected port %v allocated", i, port)
+			}
+		}
+
+		calls := sets.NewInt()
+		r.ForEach(func(port int) {
+			calls.Insert(port)
+		})
+		if len(calls) != len(tc) {
+			t.Errorf("[%d] expected %d calls, got %d", i, len(tc), len(calls))
+		}
+		if !calls.Equal(tc) {
+			t.Errorf("[%d] expected calls to equal testcase: %v vs %v", i, calls.List(), tc.List())
+		}
+	}
+}
+
 func TestSnapshot(t *testing.T) {
 	pr, err := net.ParsePortRange("10000-10200")
 	if err != nil {