diff --git a/broker/doc.go b/broker/doc.go
new file mode 100644
index 00000000..f0bff3c4
--- /dev/null
+++ b/broker/doc.go
@@ -0,0 +1,4 @@
+/*
+Package broker is an interface used for asynchronous messaging.
+*/
+package broker
diff --git a/client/client.go b/client/client.go
index 404a9132..6f4859d2 100644
--- a/client/client.go
+++ b/client/client.go
@@ -1,24 +1,3 @@
-/*
-Package client provides a method to make synchronous, asynchronous and
-streaming requests to services. By default json and protobuf codecs are
-supported.
-
-	import "github.com/micro/go-micro/client"
-
-	c := client.NewClient()
-
-	req := c.NewRequest("go.micro.srv.greeter", "Greeter.Hello", &greeter.Request{
-		Name: "John",
-	})
-
-	rsp := &greeter.Response{}
-
-	if err := c.Call(context.Background(), req, rsp); err != nil {
-		return err
-	}
-
-	fmt.Println(rsp.Msg)
-*/
 package client
 
 import (
diff --git a/client/doc.go b/client/doc.go
new file mode 100644
index 00000000..3954b032
--- /dev/null
+++ b/client/doc.go
@@ -0,0 +1,23 @@
+/*
+Package client is an interface for making requests.
+
+It provides a method to make synchronous, asynchronous and streaming requests to services.
+By default json and protobuf codecs are supported.
+
+        import "github.com/micro/go-micro/client"
+
+        c := client.NewClient()
+
+        req := c.NewRequest("go.micro.srv.greeter", "Greeter.Hello", &greeter.Request{
+                Name: "John",
+        })
+
+        rsp := &greeter.Response{}
+
+        if err := c.Call(context.Background(), req, rsp); err != nil {
+                return err
+        }
+
+        fmt.Println(rsp.Msg)
+*/
+package client
diff --git a/client/mock/mock.go b/client/mock/mock.go
index 1cc22968..337df041 100644
--- a/client/mock/mock.go
+++ b/client/mock/mock.go
@@ -123,6 +123,8 @@ func (m *MockClient) CallRemote(ctx context.Context, addr string, req client.Req
 		}
 
 		v.Set(reflect.ValueOf(r.Response))
+		
+		return nil
 	}
 
 	return fmt.Errorf("rpc: can't find service %s", req.Method())
diff --git a/cmd/doc.go b/cmd/doc.go
new file mode 100644
index 00000000..1393799d
--- /dev/null
+++ b/cmd/doc.go
@@ -0,0 +1,4 @@
+/*
+Package cmd is an interface for parsing the command line.
+*/
+package cmd
diff --git a/codec/doc.go b/codec/doc.go
new file mode 100644
index 00000000..3e1b3e17
--- /dev/null
+++ b/codec/doc.go
@@ -0,0 +1,4 @@
+/*
+Package codec is an interface for encoding messages.
+*/
+package codec
diff --git a/errors/doc.go b/errors/doc.go
new file mode 100644
index 00000000..618c419a
--- /dev/null
+++ b/errors/doc.go
@@ -0,0 +1,4 @@
+/*
+Package errors is an interface for defining detailed errors.
+*/
+package errors
diff --git a/metadata/doc.go b/metadata/doc.go
new file mode 100644
index 00000000..e60c020b
--- /dev/null
+++ b/metadata/doc.go
@@ -0,0 +1,4 @@
+/*
+Package metadata is a way of defining message headers.
+*/
+package metadata
diff --git a/registry/doc.go b/registry/doc.go
new file mode 100644
index 00000000..8edd49fd
--- /dev/null
+++ b/registry/doc.go
@@ -0,0 +1,4 @@
+/*
+Package registry is an interface for service discovery.
+*/
+package registry
diff --git a/registry/encoding.go b/registry/encoding.go
index 900773b6..b5bb9d6c 100644
--- a/registry/encoding.go
+++ b/registry/encoding.go
@@ -45,10 +45,6 @@ func encodeEndpoints(en []*Endpoint) []string {
 	var tags []string
 	for _, e := range en {
 		if b, err := json.Marshal(e); err == nil {
-			// old encoding
-			// TODO: remove in 09/2016
-			tags = append(tags, "e="+string(b))
-			// new encoding
 			tags = append(tags, "e-"+encode(b))
 		}
 	}
@@ -100,9 +96,6 @@ func encodeMetadata(md map[string]string) []string {
 		if b, err := json.Marshal(map[string]string{
 			k: v,
 		}); err == nil {
-			// old encoding
-			// TODO: remove in 09/2016
-			tags = append(tags, "t="+string(b))
 			// new encoding
 			tags = append(tags, "t-"+encode(b))
 		}
@@ -152,13 +145,7 @@ func decodeMetadata(tags []string) map[string]string {
 }
 
 func encodeVersion(v string) []string {
-	return []string{
-		// old encoding,
-		// TODO: remove in 09/2016
-		"v=" + v,
-		// new encoding,
-		"v-" + encode([]byte(v)),
-	}
+	return []string{"v-" + encode([]byte(v))}
 }
 
 func decodeVersion(tags []string) (string, bool) {
diff --git a/registry/encoding_test.go b/registry/encoding_test.go
index a58bb143..ba62111e 100644
--- a/registry/encoding_test.go
+++ b/registry/encoding_test.go
@@ -57,8 +57,8 @@ func TestEncodingEndpoints(t *testing.T) {
 		e := encodeEndpoints([]*Endpoint{ep})
 
 		// check there are two tags; old and new
-		if len(e) != 2 {
-			t.Fatalf("Expected 2 encoded tags, got %v", e)
+		if len(e) != 1 {
+			t.Fatalf("Expected 1 encoded tags, got %v", e)
 		}
 
 		// check old encoding
@@ -104,30 +104,24 @@ func TestEncodingEndpoints(t *testing.T) {
 		// HEX encoded
 		hencoded := encode(jencoded)
 		// endpoint tag
-		jepTag := "e=" + string(jencoded)
 		hepTag := "e-" + hencoded
-
-		// test old
-		testEp(ep, jepTag)
-		// test new
 		testEp(ep, hepTag)
 	}
 }
 
 func TestEncodingVersion(t *testing.T) {
 	testData := []struct {
-		decoded    string
-		encoded    string
-		oldEncoded string
+		decoded string
+		encoded string
 	}{
-		{"1.0.0", "v-789c32d433d03300040000ffff02ce00ee", "v=1.0.0"},
-		{"latest", "v-789cca492c492d2e01040000ffff08cc028e", "v=latest"},
+		{"1.0.0", "v-789c32d433d03300040000ffff02ce00ee"},
+		{"latest", "v-789cca492c492d2e01040000ffff08cc028e"},
 	}
 
 	for _, data := range testData {
 		e := encodeVersion(data.decoded)
 
-		if e[1] != data.encoded {
+		if e[0] != data.encoded {
 			t.Fatalf("Expected %s got %s", data.encoded, e)
 		}
 
@@ -148,14 +142,5 @@ func TestEncodingVersion(t *testing.T) {
 		if d != data.decoded {
 			t.Fatalf("Expected %s got %s", data.decoded, d)
 		}
-
-		d, ok = decodeVersion([]string{data.oldEncoded})
-		if !ok {
-			t.Fatalf("Unexpected %t for %s", ok, data.oldEncoded)
-		}
-
-		if d != data.decoded {
-			t.Fatalf("Expected %s got %s", data.decoded, d)
-		}
 	}
 }
diff --git a/selector/default_test.go b/selector/default_test.go
index c735040b..7897160b 100644
--- a/selector/default_test.go
+++ b/selector/default_test.go
@@ -90,7 +90,7 @@ func TestBlackList(t *testing.T) {
 	}
 
 	// blacklist all of it
-	for i := 0; i < 9; i++ {
+	for i := 0; i < 20; i++ {
 		node, err = next()
 		if err != nil {
 			t.Fatal(err)
diff --git a/selector/doc.go b/selector/doc.go
new file mode 100644
index 00000000..d0ca4295
--- /dev/null
+++ b/selector/doc.go
@@ -0,0 +1,8 @@
+/*
+Package selector is a way to load balance service nodes.
+
+It algorithmically filter and return nodes required by the client or any other system.
+Selector's implemented by Micro build on the registry but it's of optional use. One could
+provide a static Selector that has a fixed pool.
+*/
+package selector
diff --git a/selector/selector.go b/selector/selector.go
index e7dd8996..6961040a 100644
--- a/selector/selector.go
+++ b/selector/selector.go
@@ -1,9 +1,3 @@
-/*
-The Selector package provides a way to algorithmically filter and return
-nodes required by the client or any other system. Selector's implemented
-by Micro build on the registry but it's of optional use. One could
-provide a static Selector that has a fixed pool.
-*/
 package selector
 
 import (
diff --git a/server/debug.go b/server/debug.go
index 3aaf5717..18225cf7 100644
--- a/server/debug.go
+++ b/server/debug.go
@@ -2,9 +2,6 @@ package server
 
 import (
 	"github.com/micro/go-micro/server/debug"
-	proto "github.com/micro/go-micro/server/debug/proto"
-
-	"golang.org/x/net/context"
 )
 
 // We use this to wrap any debug handlers so we preserve the signature Debug.{Method}
@@ -12,10 +9,6 @@ type Debug struct {
 	debug.DebugHandler
 }
 
-func (d *Debug) Health(ctx context.Context, req *proto.HealthRequest, rsp *proto.HealthResponse) error {
-	return d.DebugHandler.Health(ctx, req, rsp)
-}
-
 func registerDebugHandler(s Server) {
 	s.Handle(s.NewHandler(&Debug{s.Options().DebugHandler}, InternalHandler(true)))
 }
diff --git a/server/debug/debug.go b/server/debug/debug.go
index accd0bc4..2712a001 100644
--- a/server/debug/debug.go
+++ b/server/debug/debug.go
@@ -1,6 +1,9 @@
 package debug
 
 import (
+	"runtime"
+	"time"
+
 	proto "github.com/micro/go-micro/server/debug/proto"
 
 	"golang.org/x/net/context"
@@ -12,16 +15,37 @@ import (
 // and /varz
 type DebugHandler interface {
 	Health(ctx context.Context, req *proto.HealthRequest, rsp *proto.HealthResponse) error
+	Stats(ctx context.Context, req *proto.StatsRequest, rsp *proto.StatsResponse) error
 }
 
 // Our own internal handler
-type debug struct{}
+type debug struct {
+	started int64
+}
 
 var (
-	DefaultDebugHandler DebugHandler = new(debug)
+	DefaultDebugHandler DebugHandler = newDebug()
 )
 
+func newDebug() *debug {
+	return &debug{
+		started: time.Now().Unix(),
+	}
+}
+
 func (d *debug) Health(ctx context.Context, req *proto.HealthRequest, rsp *proto.HealthResponse) error {
 	rsp.Status = "ok"
 	return nil
 }
+
+func (d *debug) Stats(ctx context.Context, req *proto.StatsRequest, rsp *proto.StatsResponse) error {
+	var mstat runtime.MemStats
+	runtime.ReadMemStats(&mstat)
+
+	rsp.Started = uint64(d.started)
+	rsp.Uptime = uint64(time.Now().Unix() - d.started)
+	rsp.Memory = mstat.Alloc
+	rsp.Gc = mstat.PauseTotalNs
+	rsp.Threads = uint64(runtime.NumGoroutine())
+	return nil
+}
diff --git a/server/debug/proto/debug.pb.go b/server/debug/proto/debug.pb.go
index 923ff277..7cfa7d5e 100644
--- a/server/debug/proto/debug.pb.go
+++ b/server/debug/proto/debug.pb.go
@@ -1,16 +1,18 @@
 // Code generated by protoc-gen-go.
-// source: go-micro/server/debug/proto/debug.proto
+// source: github.com/micro/go-micro/server/debug/proto/debug.proto
 // DO NOT EDIT!
 
 /*
 Package debug is a generated protocol buffer package.
 
 It is generated from these files:
-	go-micro/server/debug/proto/debug.proto
+	github.com/micro/go-micro/server/debug/proto/debug.proto
 
 It has these top-level messages:
 	HealthRequest
 	HealthResponse
+	StatsRequest
+	StatsResponse
 */
 package debug
 
@@ -23,6 +25,12 @@ var _ = proto.Marshal
 var _ = fmt.Errorf
 var _ = math.Inf
 
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
+
 type HealthRequest struct {
 }
 
@@ -32,6 +40,7 @@ func (*HealthRequest) ProtoMessage()               {}
 func (*HealthRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
 
 type HealthResponse struct {
+	// default: ok
 	Status string `protobuf:"bytes,1,opt,name=status" json:"status,omitempty"`
 }
 
@@ -40,18 +49,52 @@ func (m *HealthResponse) String() string            { return proto.CompactTextSt
 func (*HealthResponse) ProtoMessage()               {}
 func (*HealthResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{1} }
 
+type StatsRequest struct {
+}
+
+func (m *StatsRequest) Reset()                    { *m = StatsRequest{} }
+func (m *StatsRequest) String() string            { return proto.CompactTextString(m) }
+func (*StatsRequest) ProtoMessage()               {}
+func (*StatsRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{2} }
+
+type StatsResponse struct {
+	// unix timestamp
+	Started uint64 `protobuf:"varint,1,opt,name=started" json:"started,omitempty"`
+	// in seconds
+	Uptime uint64 `protobuf:"varint,2,opt,name=uptime" json:"uptime,omitempty"`
+	// in bytes
+	Memory uint64 `protobuf:"varint,3,opt,name=memory" json:"memory,omitempty"`
+	// num threads
+	Threads uint64 `protobuf:"varint,4,opt,name=threads" json:"threads,omitempty"`
+	// in nanoseconds
+	Gc uint64 `protobuf:"varint,5,opt,name=gc" json:"gc,omitempty"`
+}
+
+func (m *StatsResponse) Reset()                    { *m = StatsResponse{} }
+func (m *StatsResponse) String() string            { return proto.CompactTextString(m) }
+func (*StatsResponse) ProtoMessage()               {}
+func (*StatsResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{3} }
+
 func init() {
 	proto.RegisterType((*HealthRequest)(nil), "HealthRequest")
 	proto.RegisterType((*HealthResponse)(nil), "HealthResponse")
+	proto.RegisterType((*StatsRequest)(nil), "StatsRequest")
+	proto.RegisterType((*StatsResponse)(nil), "StatsResponse")
 }
 
 var fileDescriptor0 = []byte{
-	// 107 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0xe2, 0x52, 0x4f, 0xcf, 0xd7, 0xcd,
-	0xcd, 0x4c, 0x2e, 0xca, 0xd7, 0x2f, 0x4e, 0x2d, 0x2a, 0x4b, 0x2d, 0xd2, 0x4f, 0x49, 0x4d, 0x2a,
-	0x4d, 0xd7, 0x2f, 0x28, 0xca, 0x2f, 0xc9, 0x87, 0xb0, 0xf5, 0xc0, 0x6c, 0x25, 0x7e, 0x2e, 0x5e,
-	0x8f, 0xd4, 0xc4, 0x9c, 0x92, 0x8c, 0xa0, 0xd4, 0xc2, 0xd2, 0xd4, 0xe2, 0x12, 0x25, 0x05, 0x2e,
-	0x3e, 0x98, 0x40, 0x71, 0x41, 0x7e, 0x5e, 0x71, 0xaa, 0x10, 0x1f, 0x17, 0x5b, 0x71, 0x49, 0x62,
-	0x49, 0x69, 0xb1, 0x04, 0xa3, 0x02, 0xa3, 0x06, 0x67, 0x12, 0x1b, 0x58, 0xa7, 0x31, 0x20, 0x00,
-	0x00, 0xff, 0xff, 0x1c, 0xef, 0x98, 0xac, 0x64, 0x00, 0x00, 0x00,
+	// 201 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0x34, 0x8f, 0xbd, 0x6e, 0x83, 0x30,
+	0x14, 0x85, 0x05, 0xa5, 0x54, 0xbd, 0x2a, 0x54, 0x62, 0xa8, 0x3c, 0x56, 0x4c, 0x2c, 0xc5, 0x43,
+	0x97, 0x3e, 0x42, 0x67, 0xf2, 0x04, 0xfc, 0x5c, 0x19, 0xa4, 0x38, 0x26, 0xbe, 0xd7, 0x91, 0x32,
+	0xe7, 0xc5, 0x03, 0xb6, 0xd9, 0xce, 0xf7, 0xd9, 0xe7, 0x48, 0x17, 0xfe, 0xd4, 0xc2, 0xb3, 0x1b,
+	0xda, 0xd1, 0x68, 0xa9, 0x97, 0xd1, 0x1a, 0xa9, 0xcc, 0x4f, 0x08, 0x84, 0xf6, 0x86, 0x56, 0x4e,
+	0x38, 0x38, 0x25, 0x57, 0x6b, 0xd8, 0x84, 0xdc, 0xfa, 0x5c, 0x7f, 0x42, 0xf1, 0x8f, 0xfd, 0x99,
+	0xe7, 0x0e, 0xaf, 0x0e, 0x89, 0xeb, 0x06, 0xca, 0x43, 0xd0, 0x6a, 0x2e, 0x84, 0xd5, 0x17, 0xe4,
+	0xc4, 0x3d, 0x3b, 0x12, 0xc9, 0x77, 0xd2, 0xbc, 0x77, 0x91, 0xea, 0x12, 0x3e, 0x4e, 0x5b, 0xa2,
+	0xa3, 0xf9, 0x48, 0xa0, 0x88, 0x22, 0x36, 0x05, 0xbc, 0x6d, 0x7f, 0x2d, 0xe3, 0xe4, 0xab, 0x59,
+	0x77, 0xe0, 0xbe, 0xe9, 0x56, 0x5e, 0x34, 0x8a, 0xd4, 0x3f, 0x44, 0xda, 0xbd, 0x46, 0x6d, 0xec,
+	0x5d, 0xbc, 0x04, 0x1f, 0x68, 0x5f, 0xe2, 0xd9, 0x62, 0x3f, 0x91, 0xc8, 0xc2, 0x52, 0xc4, 0xaa,
+	0x84, 0x54, 0x8d, 0xe2, 0xd5, 0xcb, 0x2d, 0x0d, 0xb9, 0xbf, 0xeb, 0xf7, 0x19, 0x00, 0x00, 0xff,
+	0xff, 0xc6, 0x75, 0x51, 0x35, 0x13, 0x01, 0x00, 0x00,
 }
diff --git a/server/debug/proto/debug.proto b/server/debug/proto/debug.proto
index 345eae2e..8d96192e 100644
--- a/server/debug/proto/debug.proto
+++ b/server/debug/proto/debug.proto
@@ -6,11 +6,29 @@ syntax = "proto3";
 //
 // service Debug {
 // 	rpc Health(HealthRequest) returns (HealthResponse) {}
+// 	rpc Stats(StatsRequest) returns (StatsResponse) {}
 // }
 
 message HealthRequest {
 }
 
 message HealthResponse {
+	// default: ok
 	string status = 1;
 }
+
+message StatsRequest {
+}
+
+message StatsResponse {
+	// unix timestamp
+	uint64 started = 1;
+	// in seconds
+	uint64 uptime = 2;
+	// in bytes
+	uint64 memory = 3;
+	// num threads
+	uint64 threads = 4;
+	// total gc in nanoseconds
+	uint64 gc = 5;
+}
diff --git a/server/doc.go b/server/doc.go
new file mode 100644
index 00000000..c3510d46
--- /dev/null
+++ b/server/doc.go
@@ -0,0 +1,31 @@
+/*
+Package server is an interface for a micro server.
+
+It represents a server instance in go-micro which handles synchronous
+requests via handlers and asynchronous requests via subscribers that
+register with a broker.
+
+The server combines the all the packages in go-micro to create a whole unit
+used for building applications including discovery, client/server communication
+and pub/sub.
+
+        import "github.com/micro/go-micro/server"
+
+        type Greeter struct {}
+
+        func (g *Greeter) Hello(ctx context.Context, req *greeter.Request, rsp *greeter.Response) error {
+                rsp.Msg = "Hello " + req.Name
+                return nil
+        }
+
+        s := server.NewServer()
+
+
+        s.Handle(
+                s.NewHandler(&Greeter{}),
+        )
+
+        s.Start()
+
+*/
+package server
diff --git a/server/handler.go b/server/handler.go
index b944efeb..5e81e5c3 100644
--- a/server/handler.go
+++ b/server/handler.go
@@ -34,6 +34,7 @@ type Subscriber interface {
 
 type HandlerOptions struct {
 	Internal bool
+	Metadata map[string]map[string]string
 }
 
 type SubscriberOptions struct {
@@ -41,6 +42,14 @@ type SubscriberOptions struct {
 	Internal bool
 }
 
+// EndpointMetadata is a Handler option that allows metadata to be added to
+// individual endpoints.
+func EndpointMetadata(name string, md map[string]string) HandlerOption {
+	return func(o *HandlerOptions) {
+		o.Metadata[name] = md
+	}
+}
+
 // Internal Handler options specifies that a handler is not advertised
 // to the discovery system. In the future this may also limit request
 // to the internal network or authorised user.
diff --git a/server/rpc_handler.go b/server/rpc_handler.go
index e01b4b25..42ec7f0f 100644
--- a/server/rpc_handler.go
+++ b/server/rpc_handler.go
@@ -14,7 +14,10 @@ type rpcHandler struct {
 }
 
 func newRpcHandler(handler interface{}, opts ...HandlerOption) Handler {
-	var options HandlerOptions
+	options := HandlerOptions{
+		Metadata: make(map[string]map[string]string),
+	}
+
 	for _, o := range opts {
 		o(&options)
 	}
@@ -28,6 +31,11 @@ func newRpcHandler(handler interface{}, opts ...HandlerOption) Handler {
 	for m := 0; m < typ.NumMethod(); m++ {
 		if e := extractEndpoint(typ.Method(m)); e != nil {
 			e.Name = name + "." + e.Name
+
+			for k, v := range options.Metadata[e.Name] {
+				e.Metadata[k] = v
+			}
+
 			endpoints = append(endpoints, e)
 		}
 	}
diff --git a/server/server.go b/server/server.go
index 95aca9e7..79e9e5de 100644
--- a/server/server.go
+++ b/server/server.go
@@ -1,31 +1,3 @@
-/*
-Server represents a server instance in go-micro which handles synchronous
-requests via handlers and asynchronous requests via subscribers that
-register with a broker.
-
-The server combines the all the packages in go-micro to create a whole unit
-used for building applications including discovery, client/server communication
-and pub/sub.
-
-	import "github.com/micro/go-micro/server"
-
-	type Greeter struct {}
-
-	func (g *Greeter) Hello(ctx context.Context, req *greeter.Request, rsp *greeter.Response) error {
-		rsp.Msg = "Hello " + req.Name
-		return nil
-	}
-
-	s := server.NewServer()
-
-
-	s.Handle(
-		s.NewHandler(&Greeter{}),
-	)
-
-	s.Start()
-
-*/
 package server
 
 import (
diff --git a/transport/doc.go b/transport/doc.go
new file mode 100644
index 00000000..a8300db6
--- /dev/null
+++ b/transport/doc.go
@@ -0,0 +1,4 @@
+/*
+Package is an interface for synchronous communication.
+*/
+package transport
diff --git a/transport/http_transport.go b/transport/http_transport.go
index 0ad00ea1..8e2e3d8a 100644
--- a/transport/http_transport.go
+++ b/transport/http_transport.go
@@ -409,7 +409,19 @@ func (h *httpTransport) Listen(addr string, opts ...ListenOption) (Listener, err
 
 		fn := func(addr string) (net.Listener, error) {
 			if config == nil {
-				cert, err := mls.Certificate(addr)
+				hosts := []string{addr}
+
+				// check if its a valid host:port
+				if host, _, err := net.SplitHostPort(addr); err == nil {
+					if len(host) == 0 {
+						hosts = getIPAddrs()
+					} else {
+						hosts = []string{host}
+					}
+				}
+
+				// generate a certificate
+				cert, err := mls.Certificate(hosts...)
 				if err != nil {
 					return nil, err
 				}
@@ -440,6 +452,45 @@ func (h *httpTransport) String() string {
 	return "http"
 }
 
+func getIPAddrs() []string {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return nil
+	}
+
+	var ipAddrs []string
+
+	for _, i := range ifaces {
+		addrs, err := i.Addrs()
+		if err != nil {
+			continue
+		}
+
+		for _, addr := range addrs {
+			var ip net.IP
+			switch v := addr.(type) {
+			case *net.IPNet:
+				ip = v.IP
+			case *net.IPAddr:
+				ip = v.IP
+			}
+
+			if ip == nil {
+				continue
+			}
+
+			ip = ip.To4()
+			if ip == nil {
+				continue
+			}
+
+			ipAddrs = append(ipAddrs, ip.String())
+		}
+	}
+
+	return ipAddrs
+}
+
 func newHTTPTransport(opts ...Option) *httpTransport {
 	var options Options
 	for _, o := range opts {
diff --git a/transport/mock/mock.go b/transport/mock/mock.go
index 9e11577d..d544d96b 100644
--- a/transport/mock/mock.go
+++ b/transport/mock/mock.go
@@ -2,7 +2,11 @@ package mock
 
 import (
 	"errors"
+	"fmt"
+	"math/rand"
+	"strings"
 	"sync"
+	"time"
 
 	"github.com/micro/go-micro/transport"
 )
@@ -59,7 +63,12 @@ func (ms *mockSocket) Send(m *transport.Message) error {
 }
 
 func (ms *mockSocket) Close() error {
-	close(ms.exit)
+	select {
+	case <-ms.exit:
+		return nil
+	default:
+		close(ms.exit)
+	}
 	return nil
 }
 
@@ -68,7 +77,12 @@ func (m *mockListener) Addr() string {
 }
 
 func (m *mockListener) Close() error {
-	close(m.exit)
+	select {
+	case <-m.exit:
+		return nil
+	default:
+		close(m.exit)
+	}
 	return nil
 }
 
@@ -126,15 +140,25 @@ func (m *mockTransport) Listen(addr string, opts ...transport.ListenOption) (tra
 	m.Lock()
 	defer m.Unlock()
 
-	if _, ok := m.listeners[addr]; ok {
-		return nil, errors.New("already listening on " + addr)
-	}
-
 	var options transport.ListenOptions
 	for _, o := range opts {
 		o(&options)
 	}
 
+	parts := strings.Split(addr, ":")
+
+	// if zero port then randomly assign one
+	if len(parts) > 1 && parts[len(parts)-1] == "0" {
+		r := rand.New(rand.NewSource(time.Now().UnixNano()))
+		i := r.Intn(10000)
+		// set addr with port
+		addr = fmt.Sprintf("%s:%d", parts[:len(parts)-1], 10000+i)
+	}
+
+	if _, ok := m.listeners[addr]; ok {
+		return nil, errors.New("already listening on " + addr)
+	}
+
 	listener := &mockListener{
 		opts: options,
 		addr: addr,
diff --git a/transport/mock/mock_test.go b/transport/mock/mock_test.go
index b39d56c9..193d575a 100644
--- a/transport/mock/mock_test.go
+++ b/transport/mock/mock_test.go
@@ -58,3 +58,32 @@ func TestTransport(t *testing.T) {
 	}
 
 }
+
+func TestListener(t *testing.T) {
+	tr := NewTransport()
+
+	// bind / listen on random port
+	l, err := tr.Listen(":0")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l.Close()
+
+	// try again
+	l2, err := tr.Listen(":0")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l2.Close()
+
+	// now make sure it still fails
+	l3, err := tr.Listen(":8080")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l3.Close()
+
+	if _, err := tr.Listen(":8080"); err == nil {
+		t.Fatal("Expected error binding to :8080 got nil")
+	}
+}