本文中我們提出一種新的SSL VPN 體系結(jié)構(gòu)，以支持所有應(yīng)用，同時增強(qiáng)抵抗Dos 和分類的Dos 攻擊的能力。SSL VPN 的關(guān)鍵優(yōu)勢是不需要特定的客戶端軟件。當(dāng)用戶要求訪問一個服務(wù)器時，由Java Applet 編寫的SSL 客戶端模塊首先被下載到主機(jī)上。但是，
并不所有應(yīng)用都可以很好運(yùn)行的，因為客戶不能通過HTTPS 連接某些我們熟知的應(yīng)用。而且，當(dāng)SSL 端口受到Dos 或分類的Dos 攻擊時，我們不能使用VPN 進(jìn)行連接。改進(jìn)的VPN同樣使用現(xiàn)存SSL VPN 中應(yīng)用的Java Applet，但是這Applet 實現(xiàn)的功能我們稱之為動態(tài)編碼，它通過Java 遠(yuǎn)程方法調(diào)用（RMI）實現(xiàn)動態(tài)改變。VPN 客戶端Applet 可以和服務(wù)器端的VPN 服務(wù)器和防火墻進(jìn)行互操作。
關(guān)鍵字：SSL VPN 動態(tài)編碼 Java Applet RMI

Abstract：In this paper, we propose a port randomized VPN architecture such that any
application can use the VPN and the VPN has strength against DOS or DDOS. A key advantage of SSL VPN is that no specialized client software is required. When a user requests access to a server, the SSL client module, which is a Java Applet code, is downloaded into the host at first. However, it is quite likely that with a server through an HTTPS tunnel in some applications as we know. Moreover, there is the possibility that we can not use the VPN connections when the SSL port is under DOS or Distributed DOS(DDOS) attack. The proposed VPN use the same Java Applet as existing SSL VPNs use , but the function of the applet, which we call mobile code, is dynamically changed by Java Remote Method Invocation(RMI).The VPN client applet can cooperate with a VPN server and a firewall in server side.
KeyWords: SSL VPN , mobile code, Java Applet， RMI