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My ISP is Airtel Broadband. I tried opening numerous websites (apunkabollywood.com being one) but I get a clear message saying that:

Your requested URL has been blocked as per the directions received from Department of Telecommunications, Government of India. Please contact administrator for more information.

I tried nslookup for this website (it got resolved) and also I tried ping and traceroute (both were successful). That potentially rules out DNS or IP based filtering. Can someone please tell, potentially which type of filtering is being carried out by Airtel?

  • You only tried a DNS lookup (UDP over IP) and traceroute (likely ICMP), that does not rule out IP based filtering. Since all your outgoing connections are going through your ISP (well, yeah, that's what an ISP is for), they can fake any non-TLS traffic coming to you. And you expect that the page you received over HTTP/TCP/IP to look different from what you received. They may as well allow you to connect and just change the content of the connection. – grochmal Oct 24 '16 at 0:25
  • Thanks for the response. Can you tell me proper way to identify which type/types of censorship is happening? – Devashish Oct 25 '16 at 19:26
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Your ISP is almost certainly directing you through a transparent proxy. As such, all of your web traffic is going through an intermediary set of "web servers" before going on to the site you are actually trying to access. Your ISP is doing this for 2 reasons. 1. it can censor and track your traffic per its or the government's policies, and 2. it can rate limit the flow of your data.

I would suggest using a proxy service like Tor to get around these restrictions.

FYI- apunkabollywood.com resolves to 208.78.41.214 in the US.

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Domain Name Service Response Policy Zones ( DNS RPZ ) is a method that allows a nameserver administrator to overlay custom information on top of the global DNS to provide alternate responses to queries. It is currently implemented in the ISC BIND nameserver (9.8 or later). Another generic name for the DNS RPZ functionality is "DNS firewall".

The prime motivation for creating this feature was to protect users from badness on the Internet related to known-malicious global identifiers such as host names, domain names, IP addresses, or nameservers. Criminals tend to keep using the same identifiers until they are taken away from them. Unfortunately, the Internet security industry's ability to take down criminal infrastructure at domain registries, hosting providers or ISPs is not timely enough to be effective. Using RPZ, a network or DNS administrator can implement their own protection policies base based on reputation feeds from security service providers on a near-real-time basis.

Examples include: If one knows a bad host name or domain name, one can block clients from accessing it or redirect them to a walled garden. If one know a bad IP address or sub net, one can block clients from accessing host names that reference it. If one knows a name server that doesn't host anything except bad domains, one can block clients from accessing DNS information hosted by those nameservers.

content from https://dnsrpz.info/

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