2 files changed, 6 insertions, 1 deletions
diff --git a/pkg/tcpip/header/gre.go b/pkg/tcpip/header/gre.go
index 3d1cc97d9..65f5c1894 100644
--- a/pkg/tcpip/header/gre.go
+++ b/pkg/tcpip/header/gre.go
@@ -13,6 +13,11 @@ const (
 // GRE represents a GRE header stored in a byte array.
 type GRE []byte
 
+const (
+	// GREProtocolNumber is GRE's transport protocol number.
+	GREProtocolNumber tcpip.TransportProtocolNumber = 47
+)
+
 // SetLength sets the "length" field of the udp header.
 func (b GRE) SetProtocolType(protocol tcpip.NetworkProtocolNumber) {
 	binary.BigEndian.PutUint16(b[greProtocolType:], uint16(protocol))
diff --git a/pkg/tcpip/header/parse/parse.go b/pkg/tcpip/header/parse/parse.go
index 3e5336c04..de3a91227 100644
--- a/pkg/tcpip/header/parse/parse.go
+++ b/pkg/tcpip/header/parse/parse.go
@@ -176,6 +176,6 @@ func TCP(pkt *stack.PacketBuffer) bool {
 // Returns true if the header was successfully parsed.
 func GRE(pkt *stack.PacketBuffer) bool {
 	_, ok := pkt.TransportHeader().Consume(4)
-	pkt.TransportProtocolNumber = 47
+	pkt.TransportProtocolNumber = header.GREProtocolNumber
 	return ok
 }