Skip to main content

Changing focus to cover internet censorship

It’s clearly been a while since the post on this blog! I’m planning to change that and start posting again.  

The focus will change from general IT to topics related to a broad subject of internet censorship.

Internet censorship has been the main focus of my work for more than half a decade (time flies) and I’ve wanted to share what I’ve learnt for a while now.

These are some of the topics I’m planning to cover in detail over the next months and probably years:
  •     How DNS works
  •     DNS poisoning  
  •     DNS spoofing
  •     DNS cache poisoning
  •     HTTPS SNI blocking
  •     HTTP blocking
  •     HTTP redirections
  •     What’s the Great Firewall of China and what blocking techniques it implements
  •     Internet censorship in China
  •     Internet censorship in Korea
  •     Internet censorship in India
  •     Internet censorship in Indonesia

We will dive deep down to the packet level and see exactly how these attacks are implemented as well as how to diagnose and reproduce them.

That’s it for now. Stay tuned!
Labels:

Comments

Post a Comment

Popular posts from this blog

x.509 Certificates - Critical vs non-critical extensions

Extensions are used to associate additional information with the user or the key.  Each certificate extension has three attributes - extnID, critical, extnValue extnID - Extension ID - an OID that specifies the format and definitions of the extension critical - Critical flag - Boolean value extnValue - Extension value  Criticality flag specifies whether the information in an extension is important. If an application doesn't recognize the extension marked as critical, the certificate cannot be accepted. If an extension is not marked as critical (critical value False) it can be ignored by an application. In Windows, critical extensions are marked with a yellow exclamation mark,  View certificate extensions using OpenSSL: # openssl x509 -inform pem -in cert.pem -text -noout (output abbreviated)         X509v3 extensions:             X509v3 Key Usage: critical          ...
Post a Comment
Read more

DNS response and error types

In this post we explore common DNS response codes. We will cover the following responses: NOERROR SERVFAIL NXDOMAIN NODATA REFUSED Throughout article we’ll refer to the following RFCs: RFC 1034 - DOMAIN NAMES - CONCEPTS AND FACILITIES RFC 2308 - Negative Caching of DNS Queries (DNS NCACHE) RFC 2136 - Dynamic Updates in the Domain Name System (DNS UPDATE) RFC 8914 - Extended DNS Errors Response Codes - RCODEs The DNS RCODES are best defined in RFC2316 .  They signify what type of response was sent by the server. “RCODE   Response code - this four bit field is undefined in requests and set in responses.”   The table below shows the summary of the currently defined RCODEs. Mnemonic Val Description NOERROR 0 No error condition. ...
Post a Comment
Read more

DNS blocking in Indonesia

DNS based censorship and domain blocking in Indonesia is very inconsistent among ISPs. There’s a government mandated black list which the ISPs operating in the country should enforce. However, Indonesia lacks centralised internet infrastructure and has many separate ISPs. In addition, the Indonesian government granted ISPs the authority to block content at their own discretion. All of this leads to a very inconsistent DNS blocking in Indonesia. Official DNS domain blacklist in Indonesia The Government mandated DNS blacklist is published in a redacted form and can be downloaded here: https://trustpositif.kominfo.go.id/ . This is where the blocked domains get redirected to. We can search the database and check if a domain is blocked. In the screenshot below we can see that a popular cryptocurrency exchange is blocked (Ada) and that wikipedia.org is not (Tidak Ada) - thanks to Google Translate. Examples of blocked DNS queries dig binance.com @182.253.45.122 ;; global options: +cmd ;; Got ...
Post a Comment
Read more