Consider the following scenario:
- You have a server that is running Microsoft Internet Security and Acceleration (ISA) 2006.
- Internal clients use ISA 2006 as their outgoing firewall.
- Internal clients use Socks V4 to connect to an Internet resource through the ISA 2006 server.
- A Socks V4 internal client has to download a large file from the Internet resource, for example, by using FTP protocol.
In this scenario, the large file that is downloaded by the client is corrupted.
There is a problem in the Socks V4 application filter that is included together with ISA 2006. This issue does not occur when you use a third-party Socks V5 application filter.
To resolve this problem, install the ISA Server 2006 hotfix rollup package that is described in the following Microsoft Knowledge Base article:
Description of the ISA Server 2006 hotfix package: September 2011