middlebox

基本解释

The anonymity and inaccessibility of the internal hosts behind a middlebox is not a problem for client software such as web browsers, which only need to initiate outgoing connections.
这样的话，这些匿名的并且看起来难以触及的藏在NAT之后的内网主机对于像Web浏览器这种软件来说就不是一个问题,因为内网的主机只需要发起向外部的连接就可以了。
In this section we first summarize some middlebox terms. We focus hereon the two kinds of middleboxes that commonly cause problems for P2P applications.
在这一章节中，首先概要的介绍一下““代理””技术的一些术语。然后集中讨论两种造成P2P应用问题的代理机制。