Capturing Traffic between Android Device and AC Unit using Wireshark: Overcoming DNS CNAME Alias Issues

As I strive to develop an Android Things client that replicates network commands to control air conditioning (AC) units in various scenarios, I encountered a peculiar issue when attempting to capture packets using Wireshark. The goal is to build an application that can send and receive network commands between the Android device and the AC unit. However, despite sending and receiving traffic, Wireshark fails to capture it.

The problem arises from DNS CNAME aliasing, which prevents accessing SMB file servers. This article provides solutions for Windows operating systems (10, Server 2019, Server 2016, Server 2012 R2, and 7 Service Pack 1) that suffer from this issue. To resolve the problem on your MacBook Pro running Wireshark, follow these steps.

Before capturing traffic, ensure that all devices are connected to the same WiFi network. In my scenario, an Android mobile device, a networked air conditioner unit, and Wireshark running on a MacBook Pro are all connected to a Google Wifi router. The AC unit's IP address is displayed on the router's management interface.

To capture traffic in Wireshark, create a new capture configuration with default settings and enable promiscuous mode. Set the filter to 'host 192.168.100.100' (the AC unit's IP address). Start capturing and then send a command from the Android device over WiFi to the AC unit. The AC unit should respond to the network command, but no traffic will be captured by Wireshark.

To overcome this issue, you can try setting up DNS CNAME aliasing on your router or using alternative methods to access SMB file servers. If you're still experiencing issues, ensure that your WiFi adapter is set to promiscuous mode and that Wireshark has the necessary permissions to capture traffic.

In my case, I created a new capture configuration in Wireshark and used default settings, including promiscuous mode, with the filter set to 'host 192.168.100.100'. This allowed me to successfully capture traffic between the Android device and the AC unit.

By following these steps and troubleshooting techniques, you should be able to overcome DNS CNAME aliasing issues and capture traffic using Wireshark. This will enable you to develop an effective Android Things client that can replicate network commands to control AC units in various scenarios.

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