Installation guide

Deployment Primer

2-21

HTTP Double Proxy in Dependent Mode

Double proxy configuration requires two caching proxies. The first proxy is placed

between the HTTP client and the IWSVA server, and other one is placed between the

IWSVA server and the Internet. This is typically used to get the advantages of the two

configurations of the dependent modes: Proxy-ahead and Proxy-behind.

Web page requests follow this sequence:

1. The Web client sends a request to the first proxy server.

2. The first proxy server forwards the request to IWSVA.

3. IWSVA validates the request using URL Filtering/URL Access Control:

• If the URL is invalid (blocked) the HTTP service sends the HTTP client an

appropriate notice, completing the transaction.

• If the URL is valid, the HTTP service forwards the request to the second proxy

server.

4. The second proxy server performs its processing, then forwards the request to the

Web server on the Internet.

5. The contacted Web server returns a response (ideally a Web page) to second proxy

server.

6. The second proxy server caches the data (if cacheable), then delivers the

response/data to IWSVA.

7. IWSVA performs its processing on the returned data (Virus, Spyware, ActiveX

scanning), then forwards the appropriate response/data to the first proxy server.

Cached objects are downloaded by

clients directly from the Proxy

server, which minimizes delays.

ABLE

2-5.

HTTP Proxy in Dependent Mode (Proxy Behind) (Continued)

DVANTAGES

IMITATIONS