added login and permission fix

internal/usbip/server.go

@@ -421,10 +421,15 @@ func (s *Server) handleCmdSubmit(r io.Reader, hdr *URBHeader, retChan chan<- []b
 				5000, buf,
 			)
 			if err != nil {
+				log.Printf("[usbip-server] CTRL OUT seq=%d failed: %v", hdr.SeqNum, err)
 				status = -32 // -EPIPE
+			} else {
+				log.Printf("[usbip-server] CTRL OUT seq=%d OK (bmReqType=0x%02x bReq=0x%02x wVal=0x%04x)",
+					hdr.SeqNum, bmRequestType, bRequest, wValue)
 			}
 		}
 
+		log.Printf("[usbip-server] CTRL OUT seq=%d → response status=%d", hdr.SeqNum, status)
 		resp, err := BuildRetSubmit(hdr.SeqNum, hdr.DevID, hdr.Direction, hdr.Endpoint, status, nil)
 		if err != nil {
 			return err
@@ -559,6 +564,8 @@ func (s *Server) handleCmdUnlink(r io.Reader, hdr *URBHeader, retChan chan<- []b
 		return err
 	}
 
+	log.Printf("[usbip-server] UNLINK seq=%d target_seq=%d", hdr.SeqNum, body.UnlinkSeqNum)
+
 	s.mu.Lock()
 	pending, exists := s.pendingURBs[body.UnlinkSeqNum]
 	if exists {