About protocol tunneling

Used for servicing traffic that NetCache does not support

NetCache supports caching of HTTP, FTP, Gopher, RTSP, MMS, DNS, and NNTP traffic. You can, however, configure your NetCache appliance to service requests for protocols that NetCache does not support by tunneling the requests through the appliance. You might, for example, want NetCache to service traffic such as the following:

Secure traffic, such as HTTPS, SSL, and SNEWS
Traffic for protocols that do not support proxying

No browser configuration is required

When you use the protocol tunneling feature, users do not have to configure their browsers to send requests for nonstandard traffic to the NetCache appliance.

When this feature is not applicable

This feature is not for use if users configure their Web browsers or clients to access the NetCache appliance directly.

Note
The HTTP - Tunneling page of the Appliance Manager includes options to support tunneling of HTTP-based traffic to the NetCache appliance when users configure their browsers to point to the appliance.

Used for transparent or nontransparent deployments

You can use the protocol tunneling feature with either a transparent deployment (that is, you use an L4 or L7 switch or WCCP router to direct requests to the NetCache appliance) or a nontransparent deployment (no L4 or L7 switch or WCCP router).

Additional advantages of protocol tunneling

In addition to eliminating the need to configure client browsers in order to send nonstandard requests to the appliance, the protocol tunneling feature offers the following advantages:

Your firewall can be set up to accept connections from a limited number of IP addresses.
Instead of allowing direct connections to the server from clients, you could configure the firewall to accept requests from the appliance and then route client traffic through the appliance.
You can log client connections to the server, which is not possible if clients connect directly to the server. (Browsers configured to send traffic to the NetCache appliance issue CONNECT requests.)
NetCache logs each connection for which it creates a tunnel.
The NetCache appliance can provide better protection against DOS attacks than if the clients connected directly to the server.

What happens when traffic is tunneled?

With protocol tunneling, NetCache passes through specified types of nonstandard traffic without evaluating or caching it. NetCache examines only the TCP headers for the packet's source and destination and ignores the data. Because with protocol tunneling NetCache does not examine the data in a packet, NetCache does not cache objects resulting from requests serviced by this method, even if the object is cacheable. Instead, NetCache receives the request from the client and passes it through to the Internet, then receives the object from the Internet and passes it through to the client.

NetCache does not authenticate traffic that it is tunneling. Because NetCache does not examine the data in the packet, it is unaware of the protocol associated with the request.

Restrictions

Protocol tunneling has the following restrictions:

For port 443 traffic, you must configure either the SecureAdmin feature or protocol tunneling, but not both.
You cannot configure protocol tunneling for any protocol that NetCache supports. If your deployment is transparent, use the NetCache transparent proxying feature to configure NetCache to handle the protocols that it supports.
You can configure either non-transparent protocol tunneling or transparent protocol tunneling but not both.