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I know there are several types of firewalls operating at different layers of OSI. ACLs(layer 3 firewalls filter based on port numbers and IP addresses), SPI(which examines the patterns of data at layer 3 and realise that data content is malicious or not) and application layer firewalls which is capable of understanding the data at that level.

Considering this, I'll give an example and learn what I need to do. Lets say, we have a computer has access to the Internet. I want to download a file or display a web page from A website but block access to the another website/s or downloading.

To do this, I can't block access to the web browser on the 3rd party firewall because that will shut down all access. ACLs won't already do it. So, which kind of firewall Will make it possible to filter specific traffic and how?

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Not sure if this solution fits you, but transparent proxy can solidly deal with per-site restrictions on HTTP (not HTTPS) websites.

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well, i found 'internet access policy' thingy on the router tof do this. But, is this app.layer level feature or network layer? – Ozgun S Sep 9 '12 at 9:06
@Ozgun: Your router's "internet access policy" is almost certainly not the "transparent proxy" of which aledovsky writes. – RedGrittyBrick Sep 9 '12 at 10:32
you are allowed to set specific filters making use of 'Internet Access Policy'. however, ridiculously, when i choose 'deny', blocked websites part is grayed out rather than opposite. i think its the solution but needs firmware upgrade due to this bug. – Ozgun S Sep 10 '12 at 9:00

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