As a result, it also can be abused by attackers in a variety of different ways. Everyone uses it, and DNS traffic is always allowed through network firewalls. The DNS protocol analysis for incident response is a foundational protocol of the internet. DNS protocol analysis for incident response The sheer amount of data contained in an organization’s DNS records make them a common early stop for hackers performing passive reconnaissance using open-source intelligence (OSINT). Commonly-used ones include:Īdditional record types exist for DNSSEC and other less-used ones also exist. DNS includes several different types of records. While requesting a host address (A) record is a common use of DNS, it is not the only purpose. The questions sent by the client are included in the response as well. The only differences between this request and response are the flags (it contains a response) and that it has a non-zero number of answers. In this case, the request is for the A record for A DNS response uses the exact same structure as a DNS request. The request data structure informs the DNS server of the type of packet (query), the number of questions that it contains (one), and then the data in the queries. As shown at the top of the request packet, a single request can carry multiple queries. The images above show the structure of a simple DNS request and response. However, DNS can also run on TCP and a variety of other base protocols. Since DNS is a simple query-response protocol, many implementations use UDP, as there is no need for the additional guarantees provided by TCP. Also, as shown below, DNS traffic is shown in a light blue in Wireshark by default.ĭNS is a bit of an unusual protocol in that it can run on several different lower-level protocols.
The built-in dns filter in Wireshark shows only DNS protocol traffic. Wireshark makes DNS packets easy to find in a traffic capture. This issue is addressed using protocols like DNSSEC or DNS over HTTPS, which Google and Mozilla are introducing into their browsers. One of the primary ones is that all DNS traffic is sent in plaintext, making it readable and editable by eavesdroppers. While the DNS protocol is effective, it does have its downsides. Contacting the name server would then allow the browser to learn the IP address of the server hosting. com namespace to provide the IP address of the name server. Resolving would require asking a name server with knowledge of the. A domain name is broken up by the periods within it, and (theoretically) each segment is handled by a different level of name server. Instead, the DNS system uses a hierarchical structure of name servers. It is inefficient and unfeasible for each computer in the internet to track the full set of mappings from domain name to IP address. However, the computers that make up the internet work on IP addresses, not domain names.
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