Security Gateway as ICAP Client

Use Cases

A content provider provides a popular web page with a different advertisement each time the page is viewed.
Translation of web pages to different formats that are applicable for special physical devices (PDA-based or cell-phone-based browsers).
Firewalls send outgoing HTTP / HTTPS requests to a service that makes sure the URI in the HTTP / HTTPS request is allowed. In this case, it is an HTTP / HTTPS request that is being adapted, not an object returned by an HTTP / HTTPS response.
Users download an executable program through a caching proxy. This proxy acts as an ICAP client and asks an external server to check the executable for viruses before accepting it into its cache.

ICAP Decision	Description and Example
Block	ICAP Server The ICAP Server functionality in a Check Point Firewall that enables it to interact with an ICAP Client requests, send the files for inspection, and return the verdict. sends an error to the ICAP Client. ICAP Server sends a block page to the ICAP Client. For example, you can present a Check Point UserCheck Functionality in a Check Point Firewall and endpoint clients that gives users a warning when there is a potential risk of data loss or security violation. This helps users to prevent security incidents and to learn about the organizational security policy. page from the Threat Emulation, Anti-Virus, or URL Filtering Software Blade on a Check Point Firewall that allows granular control over which web sites can be accessed by a given group of users, computers or networks. Acronym: URLF. Software Blades.
Data Modification	Modification of the HTTP content. For example, your Data Loss Prevention Software Blade on a Check Point Firewall that detects and prevents the unauthorized transmission of confidential information outside the organization. Acronym: DLP. engine can replace the DOCX file attached to an email with a PDF file.
Continue / Not modified	Default Gateway or Proxy server can forward the HTTP Request / Response to its original destination.

ICAP Decision

Description and Example

Block

Data Modification

Modification of the HTTP content.

Continue / Not modified

Default Gateway or Proxy server can forward the HTTP Request / Response to its original destination.

Item	Description
1	The Client computer.
2	The Proxy server.
3	The Server computer on the Internet.
4	The ICAP Client component that runs on the Proxy server (2).
5	The ICAP Server component that runs on some computer on the network.
6	The Data Loss Prevention component that runs on some computer on the network.
A	The Client computer (1) initiates a file upload to the Server computer (3).
B	The ICAP Client component (4) intercepts the uploaded file and sends it to the ICAP Server component (5).
C	The ICAP Server component (5) forwards the uploaded file to the Data Loss Prevention component (6) for examination, whether the DLP policy allows this file to leave your network.
D	The Data Loss Prevention component (6) returns its verdict about the uploaded file.
E	The ICAP Server component (5) returns one of these to the ICAP Client component (4): A block message. The modified file.
F	The ICAP Client component (4) forwards the modified file from the ICAP Server component (5) to the Server computer (3).
G	The ICAP Client component (4) forwards the block message from the ICAP Server component (5) to the Client computer (1).

Item	Description
1	The Client computer.
2	The Proxy server.
3	The Server computer on the Internet.
4	The ICAP Client component that runs on the Proxy server (2).
5	The ICAP Server component that runs on some computer on the network.
6	The Threat Emulation component that runs on some computer on the network.
A	The Client computer (1) initiates a file download from the Server computer (3).
B	The Proxy server (2) forwards the file download request to the Server computer (3).
C	The Server (3) sends the requested file.
D	The ICAP Client component (4) intercepts the downloaded file and sends it to the ICAP Server component (5).
E	The ICAP Server component (5) forwards the downloaded file to the Threat Emulation component (6) for examination, whether this file is malicious.
F	The Threat Emulation component (6) returns its verdict about the downloaded file.
G	The ICAP Server component (5) returns one of these to the ICAP Client component (4): A block message. The modified file.
H	The ICAP Client component (4) forwards one of these responses from the ICAP Server component (5) to the Client computer (1): A block message. The modified file.