monkey-wrench

1. Well, ok& firewalls themselves aren't bad, but if you think about what asynchronous message processing means, they certainly throw an interesting monkey-wrench into the mix.
   是的，没错！其实防火墙本身并没有什么不好，但如果您考虑到异步消息处理的含义，防火墙无疑会起干扰作用。

noun

1. adjustable wrench that has one fixed and one adjustable jaw

   Synonym:    monkey wrench