isa server 2004中找不到HTTP过滤选项。

原因在于：

You couldn't access the HTTP filter config because you didnt apply the Web Proxy Filter with the HTTP protocal.

至于怎么做。

请看：

http://support.microsoft.com/kb/838708/en-us

文中讲的是如何不应用web proxy filter到HTTP协议上，反过来操作即可。如下：

1. Start the ISA Server Management tool or the Forefront Threat Management Gateway Management tool. To do this, click Start, point to All Programs, point to Microsoft ISA Server or Microsoft Forefront Threat Management Gateway, and then click ISA Server Management or Forefront Threat Management Gateway Management.
2. Expand the ISA Server computer, and then click Firewall Policy.
3. In the right pane, click the Toolbox tab, and then click Protocols.
4. In the list of protocols, expand Common Protocols, right-click HTTP, and then click Properties.
5. In the HTTP Properties dialog box, click the Parameters tab.
6. Enable the Web Proxy Filter check box, and then click OK.
7. Click Apply to save the changes to the firewall policy, and then click OK.

For more information about how to troubleshoot Web proxy traffic in ISA Server