随着宽频网络日益普及，越来越多的家庭也将改用ＡＳＤＬ或Ｃａｂｌｅ上网。虽然它们较传统拨号网络速度更快，但宽频网络也具有一些拨接网络所没有的缺点，其中最严重的问题就是网络安全。传统拨接网络没有固定的ＩＰ地址，每次连线就由服务器动态分配ＩＰ地址使用，因此不易 With the increasing popularity of broadband networks, more and more families will switch to ASDL or Cable Internet access. Although they are faster than traditional dial-up networks, broadband networks also have some shortcomings that dial-up networks do not have. The most serious problem is network security. Traditional dial-up network does not have a fixed IP address, each connection by the server dynamically assigned IP address, so not easy