Cisco Cisco Web Security Appliance S170 Guida Utente
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I R O N P O R T A S Y N C O S 6 . 5 F O R W E B U S E R G U I D E
A B O U T WE B P R O X Y S E R V I C E S
A web proxy is a computer system or software that handles World Wide Web requests of
clients by making requests of other servers on the web. The Web Security appliance can act as
a web proxy if you enable the Web Proxy feature.
clients by making requests of other servers on the web. The Web Security appliance can act as
a web proxy if you enable the Web Proxy feature.
The Web Proxy service monitors and controls traffic that originates from clients on the
internal network. Typically, the Web Proxy-enabled Web Security appliance is deployed
between clients and the firewall where it intercepts requests for content from clients to
servers.
internal network. Typically, the Web Proxy-enabled Web Security appliance is deployed
between clients and the firewall where it intercepts requests for content from clients to
servers.
You can configure the Web Proxy as one of the following types:
• Transparent Proxy. When the appliance is configured as a transparent proxy, clients are
unaware of the Web Proxy. Client applications, such as web browsers, do not have to be
configured to accommodate the appliance. You might want to configure the appliance as
a transparent proxy because it eliminates the possibility of users reconfiguring their web
browsers to bypass the appliance without knowledge of the administrator. To configure
the appliance as a transparent proxy, you must connect it to an L4 switch or a WCCP
router.
configured to accommodate the appliance. You might want to configure the appliance as
a transparent proxy because it eliminates the possibility of users reconfiguring their web
browsers to bypass the appliance without knowledge of the administrator. To configure
the appliance as a transparent proxy, you must connect it to an L4 switch or a WCCP
router.
For information about how to configure the appliance when you configure the proxy in
transparent mode, see “Configuring Transparent Redirection” on page 495.
transparent mode, see “Configuring Transparent Redirection” on page 495.
• Explicit Forward Proxy. In an explicit forward proxy configuration, the appliance acts on
behalf of client web browsers to handle requests for servers on the web. Users must
configure their web browsers to point to a single Web Security appliance. You might want
to configure the appliance as an explicit forward proxy if you do not have an L4 switch or
a WCCP router.
configure their web browsers to point to a single Web Security appliance. You might want
to configure the appliance as an explicit forward proxy if you do not have an L4 switch or
a WCCP router.
You can use the Web Security appliance in a network that includes another proxy server. For
more information about how to deploy and configure the appliance when the network
contains another proxy, see “Using the Web Security Appliance in an Existing Proxy
Environment” on page 40.
more information about how to deploy and configure the appliance when the network
contains another proxy, see “Using the Web Security Appliance in an Existing Proxy
Environment” on page 40.
The Web Proxy handles both HTTP and native FTP transactions. For more information about
working with FTP, see “Working with FTP Connections” on page 92.
working with FTP, see “Working with FTP Connections” on page 92.
Web Proxy Cache
By default, AsyncOS uses a web proxy cache to increase performance for users accessing the
web in some cases.
web in some cases.
You can edit the web proxy and proxy cache in the following ways:
• Remove a URL from the cache. Use the
evict
subcommand of the
webcache
CLI
command to remove one or more URLs from the cache.
• Specify a domain or URL to never cache. Use the
ignore
subcommand of the
webcache
CLI command to specify one or more domains or URLs that the web proxy should never