January 27th, 2016
Bonjour Monitor is a Bonjour/mDNS broadcast monitor for PCs. This allows network or wifi administrators and engineers to assess the traffic level of Bonjour on a network of VLAN. It also listens for device details and services that are being broadcast across the network.
With the proliferation of iOS, Apple TV, and BYOD – Bonjour Monitor is a useful tool in assessing what is on your network and what services they’re offering.
- Bonjour Monitor is free software.
- I’m following Google’s philosophy of release early, release often! Bonjour Monitor is alpha, v0.2
- Bonjour Monitor contains no Apple proprietary technology or code. I use my own mDNS library called Salut (it’s like Bonjour but friendlier!).
How to Use
Install Bonjour monitor on a PC or laptop that is connected on the network or VLAN you’d like to monitor. e.g. you might install on a laptop and connect that to your wireless network.
If you have iTunes or Bonjour Printer Wizard installed then the Bonjour service will can interfere with the appropriate ports. This can prevent Salut from being able to listen properly. It’s recommended that you either uninstall them or if you really want to keep them then go to Services in Control Panel (Administrative Tools) and stop the Bonjour Service.
Start Bonjour Monitor and wait for it to gather some information.
The monitor has four sections to it’s screen. On the top left is the traffic graph, underneath this is a table of mDNS traffic data, on the top right are these instructions, and below that is an area showing Devices and Services.
By default the Monitor will add up the amount of Bonjour traffic in each second and display it on a graph of 60 seconds. This can be modified from the Graph menu at the top of the screen. The sub menu “Over Time (s)” is the amount of time which the graph shows. i.e. if you chose 120 seconds then the graph would represent the last two minutes of traffic. The update interval menu allows you to set what interval the data is view over (e.g. every 1 second). Just above the graph the monitor shows the number of bytes seen within the time period represented by the entire graph.
mDNS Traffic Data
The table of mDNS traffic data tells you the source ip of an mDNS item, whether it is a request or response, it’s DNS Type, Name and Data. These are individually split out of packets that may contain multiple items – so it is an easier representation than you would get with packet sniffing software. This table is sometimes useful for debugging.
Devices and Services
This section shows any devices that the software has learnt about by monitoring the mDNS responses and also any services it has learnt about. This is seperated into two tabbed areas. Under the service tab selecting any service by clicking on it will adjust the box above it to show any discovered TXT records for the service (these are normally used to define its capabilities)
Normally the monitor is passive – that is that it learns about services and devices when it hears them mentioned. This is to avoid it having its own impact on the Bonjour traffic levels on the network. However, on occassion you might not be concerned about the exact traffic levels for a while and may want to force scan the network. The actions menu contains two options:
Services Probe – this starts a background thread that sends out requests asking for any devices running known types of services. Within about 30 seconds your Services list should be populated.
Probe Devices from Services – this menu item scans the services list, finds the devices running them, and adds them to the Devices list. Because of this you may want to run the “Services Probe” option first to maximise your results.
The latest download (version 0.2) is available for download here.
I coded this tool and have released it for free because it’s what I love to do. Do please tell others about this tool and consider me if you have any freelance projects or exciting job opportunities!