diff --git a/client/snowflake.go b/client/snowflake.go
index 648481f..fb6bbb7 100644
--- a/client/snowflake.go
+++ b/client/snowflake.go
@@ -271,7 +271,11 @@ func main() {
 		switch methodName {
 		case "snowflake":
 			// TODO: Be able to recover when SOCKS dies.
-			ln, err := pt.ListenSocks("tcp", "127.0.0.1:0")
+			listenAddr := "127.0.0.1:0"
+			if forcedListenAddr := os.Getenv("SNOWFLAKE_TEST_FORCELISTENADDR"); forcedListenAddr != "" {
+				listenAddr = forcedListenAddr
+			}
+			ln, err := pt.ListenSocks("tcp", listenAddr)
 			if err != nil {
 				pt.CmethodError(methodName, err.Error())
 				break
diff --git a/proxy/lib/snowflake.go b/proxy/lib/snowflake.go
index c6c667b..114f517 100644
--- a/proxy/lib/snowflake.go
+++ b/proxy/lib/snowflake.go
@@ -35,6 +35,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"os"
 	"strings"
 	"sync"
 	"time"
@@ -849,6 +850,11 @@ func (sf *SnowflakeProxy) Stop() {
 func (sf *SnowflakeProxy) checkNATType(config webrtc.Configuration, probeURL string) error {
 	log.Printf("Checking our NAT type, contacting NAT check probe server at \"%v\"...", probeURL)
 
+	if os.Getenv("SNOWFLAKE_TEST_ASSUMEUNRESTRICTED") != "" {
+		currentNATType = NATUnrestricted
+		return nil
+	}
+
 	probe, err := newSignalingServer(probeURL)
 	if err != nil {
 		return fmt.Errorf("Error parsing url: %w", err)