4 files changed, 91 insertions, 30 deletions

diff --git a/test/iptables/BUILD b/test/iptables/BUILD
index fa833c3b2..68eed721e 100644
--- a/test/iptables/BUILD
+++ b/test/iptables/BUILD
@@ -8,6 +8,7 @@ go_library(
         "filter_input.go",
         "iptables.go",
         "iptables_util.go",
+        "nat.go",
     ],
     importpath = "gvisor.dev/gvisor/test/iptables",
     visibility = ["//test/iptables:__subpackages__"],
diff --git a/test/iptables/filter_input.go b/test/iptables/filter_input.go
index 41bb85369..923f44e68 100644
--- a/test/iptables/filter_input.go
+++ b/test/iptables/filter_input.go
@@ -23,7 +23,6 @@ import (
 const (
 	dropPort         = 2401
 	acceptPort       = 2402
-	redirectPort     = 42
 	sendloopDuration = 2 * time.Second
 	network          = "udp4"
 )
@@ -32,7 +31,6 @@ func init() {
 	RegisterTestCase(FilterInputDropUDP{})
 	RegisterTestCase(FilterInputDropUDPPort{})
 	RegisterTestCase(FilterInputDropDifferentUDPPort{})
-	RegisterTestCase(FilterInputRedirectUDPPort{})
 }
 
 // FilterInputDropUDP tests that we can drop UDP traffic.
@@ -124,29 +122,3 @@ func (FilterInputDropDifferentUDPPort) ContainerAction(ip net.IP) error {
 func (FilterInputDropDifferentUDPPort) LocalAction(ip net.IP) error {
 	return sendUDPLoop(ip, acceptPort, sendloopDuration)
 }
-
-// FilterInputRedirectUDPPort tests that packets are redirected to different port.
-type FilterInputRedirectUDPPort struct{}
-
-// Name implements TestCase.Name.
-func (FilterInputRedirectUDPPort) Name() string {
-        return "FilterInputRedirectUDPPort"
-}
-
-// ContainerAction implements TestCase.ContainerAction.
-func (FilterInputRedirectUDPPort) ContainerAction(ip net.IP) error {
-        if err := filterTable("-t", "nat", "-A", "PREROUTING", "-p", "udp", "-j", "REDIRECT", "--to-ports", fmt.Sprintf("%d", redirectPort)); err != nil {
-		return err
-	}
-
-	if err := listenUDP(redirectPort, sendloopDuration); err != nil {
-	        return fmt.Errorf("packets on port %d should be allowed, but encountered an error: %v", acceptPort, redirectPort, err)
-	}
-
-	return nil
-}
-
-// LocalAction implements TestCase.LocalAction.
-func (FilterInputRedirectUDPPort) LocalAction(ip net.IP) error {
-        return sendUDPLoop(ip, acceptPort, sendloopDuration)
-}
diff --git a/test/iptables/iptables_test.go b/test/iptables/iptables_test.go
index d57ddc0fe..fce9247aa 100644
--- a/test/iptables/iptables_test.go
+++ b/test/iptables/iptables_test.go
@@ -178,9 +178,14 @@ func TestFilterInputDropDifferentUDPPort(t *testing.T) {
 	}
 }
 
-func TestFilterInputRedirectUDPPort(t *testing.T) {
-	if err := singleTest(FilterInputRedirectUDPPort{}); err != nil {
+func TestFilterNATRedirectUDPPort(t *testing.T) {
+	if err := singleTest(FilterNATRedirectUDPPort{}); err != nil {
 		t.Fatal(err)
 	}
 }
 
+func TestFilterNATDropUDP(t *testing.T) {
+        if err := singleTest(FilterNATDropUDP{}); err != nil {
+	        t.Fatal(err)
+	}
+}
diff --git a/test/iptables/nat.go b/test/iptables/nat.go
new file mode 100644
index 000000000..6deabf217
--- /dev/null
+++ b/test/iptables/nat.go
@@ -0,0 +1,83 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package iptables
+
+import (
+        "fmt"
+        "net"
+)
+
+const (
+        redirectPort     = 42
+)
+
+func init() {
+        RegisterTestCase(FilterNATRedirectUDPPort{})
+	RegisterTestCase(FilterNATDropUDP{})
+}
+
+// FilterInputRedirectUDPPort tests that packets are redirected to different port.
+type FilterNATRedirectUDPPort struct{}
+
+// Name implements TestCase.Name.
+func (FilterNATRedirectUDPPort) Name() string {
+        return "FilterNATRedirectUDPPort"
+}
+
+// ContainerAction implements TestCase.ContainerAction.
+func (FilterNATRedirectUDPPort) ContainerAction(ip net.IP) error {
+        if err := filterTable("-t", "nat", "-A", "PREROUTING", "-p", "udp", "-j", "REDIRECT", "--to-ports",
+	fmt.Sprintf("%d", redirectPort)); err != nil {
+		return err
+	}
+
+	if err := listenUDP(redirectPort, sendloopDuration); err != nil {
+	        return fmt.Errorf("packets on port %d should be allowed, but encountered an error: %v", redirectPort, err)
+	}
+
+	return nil
+}
+
+// LocalAction implements TestCase.LocalAction.
+func (FilterNATRedirectUDPPort) LocalAction(ip net.IP) error {
+        return sendUDPLoop(ip, acceptPort, sendloopDuration)
+}
+
+// FilterNATDropUDP tests that packets are not received in ports other than redirect port.
+type FilterNATDropUDP struct{}
+
+// Name implements TestCase.Name.
+func (FilterNATDropUDP) Name() string {
+        return "FilterNATDropUDP"
+}
+
+// ContainerAction implements TestCase.ContainerAction.
+func (FilterNATDropUDP) ContainerAction(ip net.IP) error {
+        if err := filterTable("-t", "nat", "-A", "PREROUTING", "-p", "udp", "-j", "REDIRECT", "--to-ports",
+	fmt.Sprintf("%d", redirectPort)); err != nil {
+		return err
+	}
+
+	if err := listenUDP(acceptPort, sendloopDuration); err == nil {
+		return fmt.Errorf("packets on port %d should have been redirected to port %d", acceptPort, redirectPort)
+	}
+
+	return nil
+}
+
+// LocalAction implements TestCase.LocalAction.
+func (FilterNATDropUDP) LocalAction(ip net.IP) error {
+        return sendUDPLoop(ip, acceptPort, sendloopDuration)
+}