阅读下面的材料，根据要求写一篇不少于800字的文章。(60分)

这是一座直插云霄的大山。两只山羊跳过深不可测的“亡命峡”，穿过使人失魂落魄的“一线天“，翻过凶险的“阎王鼻子”，眼看顶峰已近在咫尺，一块巨大的石头挡住了去路，它俩想尽一切办法，用完浑身的力气，还是无法征服这个障碍。

白山羊打算退回去，另寻新路；黑山羊却执意不肯：“走回头路，我决不干!要走你走吧!”

白山羊无法说服黑山羊，只好独自退回去了。一个月后，白山羊出现在高高的山顶上，而黑山羊依然在巨石前徘徊。

要求：选准角度，明确立意；自选文体，自拟标题；不要脱离材料内容及含意的范围作文；不要套作，不得抄袭。

Most IP layer-based proxy mechanisms, such as network address translation (NAT), only support uni-directional proxy, from the internal network to external network (the Internet). The proxy establishes the communication channel by (86) IP addresses. The IP addresses must be (87) . These proxy mechanisms prevent applications that must establish return data channels from establishing their data channels, such as, multimedia applications. IP layer-based proxy mechanisms need additional software (88) for each application that uses (89) channels. SOCKS identifies communication targets through domain names, overcoming the restriction of using private IP addresses. SOCKS can use domain names to establish communication between separate LANs, with (90) IP addresses.

A．manufacturing

B．manipulating

C．conduct

D．implement