diff --git a/tools/functional-tester/etcd-tester/failure.go b/tools/functional-tester/etcd-tester/failure.go
index cd63daa09..82392087d 100644
--- a/tools/functional-tester/etcd-tester/failure.go
+++ b/tools/functional-tester/etcd-tester/failure.go
@@ -17,6 +17,7 @@ package main
 import (
 	"fmt"
 	"math/rand"
+	"os/exec"
 	"time"
 )
 
@@ -177,3 +178,20 @@ type failureNop failureByFunc
 
 func (f *failureNop) Inject(c *cluster, round int) error  { return nil }
 func (f *failureNop) Recover(c *cluster, round int) error { return nil }
+
+type failureExternal struct {
+	failure
+
+	description string
+	scriptPath  string
+}
+
+func (f *failureExternal) Inject(c *cluster, round int) error {
+	return exec.Command(f.scriptPath, "enable", fmt.Sprintf("%d", round)).Run()
+}
+
+func (f *failureExternal) Recover(c *cluster, round int) error {
+	return exec.Command(f.scriptPath, "disable", fmt.Sprintf("%d", round)).Run()
+}
+
+func (f *failureExternal) Desc() string { return f.description }
diff --git a/tools/functional-tester/etcd-tester/failure_agent.go b/tools/functional-tester/etcd-tester/failure_agent.go
index d23a69781..5dddec530 100644
--- a/tools/functional-tester/etcd-tester/failure_agent.go
+++ b/tools/functional-tester/etcd-tester/failure_agent.go
@@ -145,3 +145,10 @@ func newFailureNop() failure {
 		description: "no failure",
 	}
 }
+
+func newFailureExternal(scriptPath string) failure {
+	return &failureExternal{
+		description: fmt.Sprintf("external fault injector (script: %s)", scriptPath),
+		scriptPath:  scriptPath,
+	}
+}
diff --git a/tools/functional-tester/etcd-tester/main.go b/tools/functional-tester/etcd-tester/main.go
index 3574ee30b..ab2839f13 100644
--- a/tools/functional-tester/etcd-tester/main.go
+++ b/tools/functional-tester/etcd-tester/main.go
@@ -50,6 +50,7 @@ func main() {
 	isV2Only := flag.Bool("v2-only", false, "'true' to run V2 only tester.")
 	stresserType := flag.String("stresser", "default", "specify stresser (\"default\" or \"nop\").")
 	failureTypes := flag.String("failures", "default,failpoints", "specify failures (concat of \"default\" and \"failpoints\").")
+	externalFailures := flag.String("external-failures", "", "specify a path of script for enabling/disabling an external fault injector")
 	flag.Parse()
 
 	eps := strings.Split(*endpointStr, ",")
@@ -93,6 +94,14 @@ func main() {
 		failures = makeFailures(*failureTypes, c)
 	}
 
+	if externalFailures != nil && *externalFailures != "" {
+		if len(failures) != 0 {
+			plog.Errorf("specify only one of -failures or -external-failures")
+			os.Exit(1)
+		}
+		failures = append(failures, newFailureExternal(*externalFailures))
+	}
+
 	if len(failures) == 0 {
 		plog.Infof("no failures\n")
 		failures = append(failures, newFailureNop())