diff --git a/src/net/SocketDescriptor.cxx b/src/net/SocketDescriptor.cxx
index c6846c6d0..11624a2d4 100644
--- a/src/net/SocketDescriptor.cxx
+++ b/src/net/SocketDescriptor.cxx
@@ -32,6 +32,16 @@ SocketDescriptor::IsStream() const noexcept
 	return GetType() == SOCK_STREAM;
 }
 
+#ifndef _WIN32
+
+int
+SocketDescriptor::GetProtocol() const noexcept
+{
+	return GetIntOption(SOL_SOCKET, SO_PROTOCOL, -1);
+}
+
+#endif // !_WIN32
+
 #ifdef _WIN32
 
 void
diff --git a/src/net/SocketDescriptor.hxx b/src/net/SocketDescriptor.hxx
index 0f90fb9d5..a25641c0c 100644
--- a/src/net/SocketDescriptor.hxx
+++ b/src/net/SocketDescriptor.hxx
@@ -101,6 +101,15 @@ public:
 	[[gnu::pure]]
 	bool IsStream() const noexcept;
 
+#ifndef _WIN32
+	/**
+	 * Determine the socket protocol (SO_PROTOCOL),
+	 * e.g. IPPROTO_SCTP.  Returns -1 on error.
+	 */
+	[[gnu::pure]]
+	int GetProtocol() const noexcept;
+#endif // !_WIN32
+
 	static constexpr SocketDescriptor Undefined() noexcept {
 #ifdef _WIN32
 		return SocketDescriptor{INVALID_SOCKET};