Internet users are well aware that thousands of websites in India, many of which share files or porn sites, are prohibited in India. Now a report sheds light on the methods used by Jio and Airtel, which are major internet service providers in the country, to block these websites. A report notes that Airtel – and possibly Jio, but unconfirmed, use middleboxes, which are routers specially configured to resolve website DNS, to block websites in India.
Researchers from the Center for Internet and Society (CIS) tracked down 25 middleboxes that are used to block websites at Airtel. According to the report, both Airtel and Jio rely on Server Name Indication (SNI), a website identifier on a server, to perform the blocking.
Medianama’s report cited a blog post by Gurshabad Grover and Kushagra Singh, who attributed 25 middleboxes to Airtel censoring Internet traffic. First they got his IP address and mapped it to a public database of IP addresses. From there, they could identify 25 middleboxes registered on Airtel.
It is worth noting that in blocking the Airtel and Jio websites they only follow government directives. The order to block a website in India comes from the Department of Telecommunications and Internet Service Providers must comply with it. Although it is another matter that these orders are not publicly available and there is no way for Indian users to know if blocking a website is being done for a valid reason or if it is being executed only because someone somewhere has decided that some websites should be banned in India.
Blocking websites in India is nothing new. Over the years we have seen repeatedly blocking a number of websites for a variety of reasons, including based on John Doe’s court orders, however, the latest report makes it clear that unlike the rudimentary website blocking carried out Based on previously banned lists of domain names, Airtel and Jio are now employing more sophisticated blocking measures, similar to the ways and tools China uses to block thousands of websites.
Mainly it seems that Airtel and Jio rely on the server name indication (SNI) to identify the requested website and then block it in case the website is on the banned list sites in India. In case a user tries to access this website, he gets “PR_CONNECT_RESET_ERROR”. For example, if a user tries to access the Torrentz2 website, they will get the following error.
Using SNI-based blocking, Airtel and Jio can also ban HTTPS websites. This is because SNI is not encrypted and reveals the details of which website will be accessed, although HTTPS prevents ISPs from understanding what a user is doing on a secure account. To counter these web browsers, particularly Mozilla Firefox, they have begun to implement eSNI, which is encrypted, but for now the functionality remains experimental for all practical purposes.
“Users attempting to access websites usually contact the ISP’s DNS directory to translate a human-scanned address such as xyz.com into its network address,” the researchers noted. “Some ISPs in India, such as BSNL and MTNL, respond with incorrect network addresses to user questions about the websites they wish to block.”
So they pointed out that ISPs like Airtel and Jio use the SNI method. “ISPs such as Jio, Airtel and Vodafone monitor this field for the names of websites they wish to block, intercept such requests and return whatever they want as a response,” the researchers noted in their blog post.
Although the researchers were able to identify the middleboxes used by Airtel, they were unable to identify such routers for Jio with 100% security. This, they noted, was likely because Jio configured middlebox using proxy server.
Researchers found that Airtel uses middleboxes to resolve DNS and block websites using these specially configured routers. Jio is probably using the same method too.
- Airtel uses 25 middleboxes to block websites in India, a report notes.
- Jio probably uses the same way to block sites through SNI, although the researchers could not confirm this.
- Researchers argue the blockade of sites by Airtel, Jio is similar to Chinese censorship.