diff --git a/infra/conf/cfgcommon/sniffer/sniffer.go b/infra/conf/cfgcommon/sniffer/sniffer.go
new file mode 100644
index 000000000..9cf246c1b
--- /dev/null
+++ b/infra/conf/cfgcommon/sniffer/sniffer.go
@@ -0,0 +1,42 @@
+package sniffer
+
+import (
+	"github.com/v2fly/v2ray-core/v4/app/proxyman"
+	"github.com/v2fly/v2ray-core/v4/infra/conf/cfgcommon"
+	"strings"
+)
+
+//go:generate go run github.com/v2fly/v2ray-core/v4/common/errors/errorgen
+
+type SniffingConfig struct {
+	Enabled      bool                  `json:"enabled"`
+	DestOverride *cfgcommon.StringList `json:"destOverride"`
+	MetadataOnly bool                  `json:"metadataOnly"`
+}
+
+// Build implements Buildable.
+func (c *SniffingConfig) Build() (*proxyman.SniffingConfig, error) {
+	var p []string
+	if c.DestOverride != nil {
+		for _, domainOverride := range *c.DestOverride {
+			switch strings.ToLower(domainOverride) {
+			case "http":
+				p = append(p, "http")
+			case "tls", "https", "ssl":
+				p = append(p, "tls")
+			case "fakedns":
+				p = append(p, "fakedns")
+			case "fakedns+others":
+				p = append(p, "fakedns+others")
+			default:
+				return nil, newError("unknown protocol: ", domainOverride)
+			}
+		}
+	}
+
+	return &proxyman.SniffingConfig{
+		Enabled:             c.Enabled,
+		DestinationOverride: p,
+		MetadataOnly:        c.MetadataOnly,
+	}, nil
+}
diff --git a/infra/conf/v4/v2ray.go b/infra/conf/v4/v2ray.go
index 4ccd7c19a..306de1525 100644
--- a/infra/conf/v4/v2ray.go
+++ b/infra/conf/v4/v2ray.go
@@ -3,6 +3,7 @@ package v4
 import (
 	"encoding/json"
 	"github.com/v2fly/v2ray-core/v4/infra/conf/cfgcommon/loader"
+	"github.com/v2fly/v2ray-core/v4/infra/conf/cfgcommon/sniffer"
 	"github.com/v2fly/v2ray-core/v4/infra/conf/synthetic/dns"
 	"github.com/v2fly/v2ray-core/v4/infra/conf/synthetic/log"
 	"github.com/v2fly/v2ray-core/v4/infra/conf/synthetic/router"
@@ -57,39 +58,6 @@ func toProtocolList(s []string) ([]proxyman.KnownProtocols, error) {
 	return kp, nil
 }
 
-type SniffingConfig struct {
-	Enabled      bool                  `json:"enabled"`
-	DestOverride *cfgcommon.StringList `json:"destOverride"`
-	MetadataOnly bool                  `json:"metadataOnly"`
-}
-
-// Build implements Buildable.
-func (c *SniffingConfig) Build() (*proxyman.SniffingConfig, error) {
-	var p []string
-	if c.DestOverride != nil {
-		for _, domainOverride := range *c.DestOverride {
-			switch strings.ToLower(domainOverride) {
-			case "http":
-				p = append(p, "http")
-			case "tls", "https", "ssl":
-				p = append(p, "tls")
-			case "fakedns":
-				p = append(p, "fakedns")
-			case "fakedns+others":
-				p = append(p, "fakedns+others")
-			default:
-				return nil, newError("unknown protocol: ", domainOverride)
-			}
-		}
-	}
-
-	return &proxyman.SniffingConfig{
-		Enabled:             c.Enabled,
-		DestinationOverride: p,
-		MetadataOnly:        c.MetadataOnly,
-	}, nil
-}
-
 type MuxConfig struct {
 	Enabled     bool  `json:"enabled"`
 	Concurrency int16 `json:"concurrency"`
@@ -155,7 +123,7 @@ type InboundDetourConfig struct {
 	Allocation     *InboundDetourAllocationConfig `json:"allocate"`
 	StreamSetting  *StreamConfig                  `json:"streamSettings"`
 	DomainOverride *cfgcommon.StringList          `json:"domainOverride"`
-	SniffingConfig *SniffingConfig                `json:"sniffing"`
+	SniffingConfig *sniffer.SniffingConfig        `json:"sniffing"`
 }
 
 // Build implements Buildable.