The Things I Find

So, I have a Linksys WRT54GL router, and I’m running the Tomato operating system on it. Tomato is brilliant; it looks nice, it’s easy to install and configure, and best of all it’ll run the router in Wireless Client mode. This turns the router into just another wireless client, connecting to my existing access point in the same way my laptop does - including using a lengthy password and WPA1 encryption. In my case the router then acts like a switch - forwarding traffic received on its wireless interface to the appropriate ports on its built-in four port switch. My other PCs, printers, XBox etc then plug into the router, and have seamless connectivity over wireless to the rest of my network. No driver issues, I don’t need to leave a PC on all the time, and only a single radio contending for the link (which allows better throughput). Brilliant.

There are, however, a couple of things Tomato doesn’t do; one of which is support SNMP - the Simple Network Management Protocol. SNMP is a standard way for devices to report statistics about their operation - CPU usage, memory usage, packets received and the like. You can then use a package like MRTG to collate that data from all of the devices in your network, and see what’s going on. In my day job, we use it to diagnose problems and to decide where best to spend our budget.

But back to Tomato… Tomato’s not as easily extensible as, say OpenWRT with its ipkg system. However, what you can do is run an executable from a CIFS/SMB network share - like, for example, this:

HOWTO: SNMPd on Tomato

This is, as the name suggests, a How-To on running the OpenWRT SNMP daemon from a network share. Essentially, you download the OpenWRT SNMP daemon executable, save it to a network share, create a config for it, and then call the daemon (after a 30 second sleep to make sure the network’s up) from the “Firewall” script. While it’s not perfect - the demon will crash if you do an SNMP walk against it - it’s stable enough to hand out network stats on request. In my case it’s been up for four days, handing out stats every five minutes, with no trouble.

On a final note, running MRTG at home is… depressing. For the most part, I’d be fine running an Ethernet hub; it’s rare that my total network utilisation crosses ten megabits per second. The only exception is when copying (not watching/listening to) files between machines, but even then it’s usually something that could easily be run overnight. Which raises the question - why do so many people buy gigabit switches for home use?