Empty1 - Empty Packet

This module is designed to send an empty response, composed entirely of an empty packet.

In both UDP and TCP modes, the client/resolver will receive only the UDP or TCP packet header without any data or payload.

Category: Empty responses

Format

empty1.yourdomain.com

This module has no parameters.

Examples

In this example, we request an empty packet as the response in UDP mode, resulting in the client making three attempts to resolve the error:

# dig empty1.yourdomain.com @127.0.0.1

;; Warning: short (< header size) message received
;; communications error to 127.0.0.1#53: timed out
;; Warning: short (< header size) message received
;; communications error to 127.0.0.1#53: timed out
;; Warning: short (< header size) message received
;; communications error to 127.0.0.1#53: timed out

; <<>> DiG 9.18.10-2-Debian <<>> empty1.yourdomain.com @127.0.0.1
;; global options: +cmd
;; no servers could be reached

Download PCAP File

In this case, we request an empty packet as the response in TCP mode, resulting in the client again making three attempts to resolve the error:

# dig empty1.yourdomain.com @127.0.0.1 +tcp

;; communications error to 127.0.0.1#53: end of file
;; communications error to 127.0.0.1#53: end of file
;; communications error to 127.0.0.1#53: end of file

; <<>> DiG 9.18.10-2-Debian <<>> empty1.yourdomain.com @127.0.0.1 +tcp
;; global options: +cmd
;; no servers could be reached

Download PCAP File

Like other features, you can append anything to the feature name to avoid receiving cached responses from the target DNS resolver. This forces the target resolver to actively communicate with our PolarDNS server instead of responding with cached answers. Using a random number is the most effective strategy:

# dig empty1${RANDOM}.yourdomain.com @10.211.55.2

;; Warning: short (< header size) message received
;; communications error to 10.211.55.2#53: timed out
;; Warning: short (< header size) message received
;; communications error to 10.211.55.2#53: timed out
;; Warning: short (< header size) message received
;; communications error to 10.211.55.2#53: timed out

; <<>> DiG 9.18.10-2-Debian <<>> empty124422.yourdomain.com @10.211.55.2
;; global options: +cmd
;; no servers could be reached

Download PCAP File

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