diff --git a/metropolis/test/launch/launch.go b/metropolis/test/launch/launch.go
index daf2f4b..e8df009 100644
--- a/metropolis/test/launch/launch.go
+++ b/metropolis/test/launch/launch.go
@@ -170,6 +170,10 @@
 	// that is normally the first network interface. If this is set PortMap is ignored.
 	// Mostly useful for speeding up QEMU's startup time for tests.
 	DisableHostNetworkInterface bool
+
+	// PcapDump can be used to dump all network traffic to a pcap file.
+	// If unset, no dump is created.
+	PcapDump string
 }
 
 // RunMicroVM launches a tiny VM mostly intended for testing. Very quick to boot
@@ -257,6 +261,15 @@
 			"-device", "virtio-net-device,netdev=usernet0,mac="+HostInterfaceMAC.String())
 	}
 
+	if !opts.DisableHostNetworkInterface && opts.PcapDump != "" {
+		qemuNetDump := QemuValue{
+			"id":     {"usernet0"},
+			"netdev": {"usernet0"},
+			"file":   {opts.PcapDump},
+		}
+		extraArgs = append(extraArgs, "-object", qemuNetDump.ToOption("filter-dump"))
+	}
+
 	var stdErrBuf bytes.Buffer
 	cmd := exec.CommandContext(ctx, "qemu-system-x86_64", append(baseArgs, extraArgs...)...)
 	cmd.Stdout = opts.SerialPort