DNSFISHs

DNSFish is a domain name system (DNS) tunneling technique used to bypass filtering and censorship measures. It involves creating a series of domain names that are used to encrypt and transport data through a DNS query. The technique relies on the fact that most web filtering systems only block access to known malicious websites.

The DNS Fish method involves the client and server communicating through a series of "leapfrog" domains. The client sends a request to the first domain in the chain, which then forwards the request to the second domain, and so on. The server is located behind the second-to-last domain in the chain. By using a series of ephemeral domains, the client and server can maintain a secure connection without being detected by filters.

One notable characteristic of DNSFish is its ability to support bidirectional communication. This means that the server can initiate communication with the client, in addition to the client initiating communication with the server.

The use of DNSFish has been observed by security researchers in various regions where internet access is censored. It is generally considered a workaround for countries that block access to specific websites or services. However, security researchers have also noted that DNS Fish can be vulnerable to detection and disruption by sophisticated filtering systems.