asuswrt on irq5 test

Detailed Wireless Client Stats with collectd

Thu, 01 Aug 2019 11:59:00 +0000

collectd has always been able to grab interface traffic statistics from Linux. But what if we want to collect data about individual WiFi clients that connect to it? How much bandwidth is each of the clients using?

That information is already being recorded by the wireless driver; all we need to do is to query it. Turns out you can do that with the wl utility. This is Broadcom’s proprietary tool to control and query the wireless interfaces.

To do this, first use wl to get associated stations:

wl -i eth2 assoclist

Given a particular MAC address that is associated to the AP, query its info using sta_info:

# wl -i eth2 sta_info d4:a3:00:aa:bb:cc
STA d4:a3:00:aa:bb:cc:
 aid:2
 rateset [ 6 9 12 18 24 36 48 54 ]
 idle 0 seconds
 in network 16 seconds
 state: AUTHENTICATED ASSOCIATED AUTHORIZED
 flags 0x11e03b: BRCM WME N_CAP VHT_CAP AMPDU AMSDU
 HT caps 0x6f: LDPC 40MHz SGI20 SGI40
 VHT caps 0x43: LDPC SGI80 SU-BFE
 tx data pkts: 663916
 tx data bytes: 68730715
 tx ucast pkts: 155
 tx ucast bytes: 42699
 tx mcast/bcast pkts: 663761
 tx mcast/bcast bytes: 68688016
 tx failures: 0
 rx data pkts: 234
 rx data bytes: 73557
 rx ucast pkts: 192
 rx ucast bytes: 62971
 rx mcast/bcast pkts: 42
 rx mcast/bcast bytes: 10586
 rate of last tx pkt: 866667 kbps
 rate of last rx pkt: 780000 kbps
 rx decrypt succeeds: 195
 rx decrypt failures: 1
 tx data pkts retried: 19
 tx data pkts retry exhausted: 0
 per antenna rssi of last rx data frame: -61 -56 -59 0
 per antenna average rssi of rx data frames: -61 -56 -57 0
 per antenna noise floor: -104 -98 -98 0

The “easy way” is probably to write a shell script, invoked via the Exec plugin that calls wl multiple times (once per interface, and once for each WiFi client) and uses grep or awk to get the information we need. This won’t be performant, of course.

wl itself does have quite a fair bit of overhead. It does some verification of the provided interface name. It checks for the Broadcom driver magic to ensure that the interface is a Broadcom device. It then needs to convert the MAC address from the argument string to binary, and vice-versa. Sure, that’s not really much “these days”, but we can definitely do better.

Instead, let’s short-circuit the process and write a plugin that directly collects the data, without going through wl. This way, we avoid creating several new processes for every query.

Extending ASUSWRT Functionality, Part 2

Fri, 28 Dec 2018 00:11:00 +0000

Following up from my earlier post, Asus has released faster and beefier routers. But perhaps the more important change here is that they have moved from MIPS in the RT-N56U to ARM in newer routers. I have also upgraded to the RT-AC68U for better reception and hopefully to fix the poor battery life experienced by my Android tablet.

After upgrading, I noticed that the method I described back then no longer works. Someone also noticed this, as they translated key portions of my post into Chinese, while pointing out some of the steps that didn’t work.

In this post, I’ll summarize the key changes required to get it working again.

Hacking Functionality into ASUSWRT Routers

Mon, 10 Dec 2012 00:10:00 +0000

This weekend, I spent some time to replace my aged Linksys WRT54G wireless router, which is running DD-WRT. The WRT54G is slow by today’s wireless standards and since I sync my iOS devices wirelessly, the speed was getting quite unbearable. When I bought my Macbook Pro in 2007, it already has draft 802.11n support and fast-forward to 2012, my iPad (1st generation) and iPhone 5 both support the 5GHz band.

The ASUS RT-N56U wireless router ranks up there on wireless performance, and the “feature” I was really after was a router that can run an alternative firmware such as Tomato or DD-WRT. The really good news is, I figured out how to get the functionality I wanted while still using the official ASUS firmware.

For proper reviews and better photos, you might want to check out these other reviews:

SmallNetBuilder: ASUS RT-N56U Black Diamond Dual-Band Gigabit Wireless-N Router Reviewed
FoxNetwork: ASUS RT-N56U or hardware NAT acceleration
(I quite like their professionally taken product photos and their reverse-engineering work)

Read on to find my short review, as well as how you can run your own programs on the router without using a third-party firmware.