Microsoft ISA/TMG Agenthttp://www.websense.com/content/support/library/deployctr/v77/dic_ds_isa_agt.aspx
        <h2>Deployment and Installation Center </h2>
        <h3>Microsoft ISA/TMG agent</h3>
        The ISA/TMG agent receives all Web connections from a Microsoft ISA Server or Forefront TMG network and forwards them to the Data Security policy engine. It then receives the analyzed information back from the policy engine and forwards it to the recipients on the Web.
        <p>The ISA/TMG agent supports the permit and block actions, and it receives authentication information from the client on its way to the proxy to identify users. It supports both HTTPS and HTTP traffic. </p>
        <p>The ISA/TMG agent requires 1 GB free disk space on the ISA Server machine. The installer will not allow you to install ISA/TMG agent if available space is less. </p>
        <p>If you are using the ISA agent on an ISA array, be sure to install it on every member of the array; otherwise the configuration will be out of sync and ISA may become non-functional. </p>
        <p>Click <b>View Complete Document</b> for more. </p>