Netgear GS108T administration and Browsers
Some time ago I bought a secondhand Netgear GS108T managed switch to use on my small local network. I selected it because of its 'mirroring' capability. This was so that I could run a network monitoring tool such as Wireshark and capture the network traffic going to/from something else my network. (What is that Chinese IP camera connecting to?)
Usually network switches do just that - act as switch and just route traffic between the two (or more) ports that 'need to know'. With mirroring you can tell the switch: "Whatever passes through this port please also copy it to this port". "This port" being the one which the computer running Wireshark is plugged into.
My particular GS108T is a GS108Tv1 running the latest(!) firmware V22.214.171.124 which was released in June 2012.
The GS108T is administered using a web-based interface - you just point a browser at it and away you go. To find out what IP address it is using you can use some Netgear supplied software, or you can just check the 'connected devices' list on your local router.
However the real problem is, that having navigated to the 'Mirroring' setup screen and made the changes you want to do, the Apply button does nothing.
Above I say 'modern browsers', but a quick Google shows me that others were complaining about the Apply button not working on Netgear forums back in at least 2016. In my (admittedly not exhaustive) Googling on this topic I have never seen any acknowledgement from the Netgear Support people that there is an actual problem. Their response has always been a steady stream of: "Reset the switch", "Reload the firmware", "Try a different browser", "maybe your hardware is faulty"....
Having said "modern browsers don't work" I have found that the latest version of Internet Explorer (version 11) supplied with Windows 10 does work. I find this a little ironic as (a) Microsoft are trying to get us to dump IE in favour of Edge, and (b) IE versions usually have small quirks in the way they interpret or extend the standards.
Just FYI here are a few screen shots of the Mirroring page on various browsers:
The above is what you get with Chrome, Edge and Firefox running on Windows 10.
The above is what you get with Opera (v9) and the Chromium browser running on Linux.
The above is what you get with Internet Explorer 11 on Windows 10.
Basically there are three options to set up mirroring on the GS108Tv1:
- Use Internet Explorer 11
- Type in the wanted settings in the URL (see below)
- Find an old browser (such as Firefox 3.6.0?)
Taking the elements of the URL in turn:
192.168.10.26 The address of your switch - adjust to suit. mirror.cgi Run the mirror.cgi script to save the results ? Start of the parameter list mode=3 Sets the mode of operation
0 = Disable
1 = Tx Only
2 = Rx Only
3 = Tx and Rx
& Separator between name/value pairs mtp=8 The number of the monitoring port & Separator between name/value pairs config=00100002 A string of 8 digits representing ports 1-8, where
0 indicates the port is not mirrored.
1 indicates the port is mirrored.
2 indicates the port to which everything is mirrored.
In this example port 3 is being mirrored to port 8.
In summary: If you have a Windows 10 box to hand fire up Internet Explorer otherwise spend a few seconds handcrafting the configuration URL in the address bar of what ever browser you happen to be using.
Note: I believe the problem does exist in other Netgear switches of this era which probably share the same code.