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Shane Alcock's Blog




Started working on integrating some of the STRATUS metrics into NNTSC so that we can explore using time-series based event detection to highlight potentially interesting file interactions. Going forward, I'm going to be splitting my time 50:50 between STRATUS development and WAND research work -- existing research might progress a bit slower as a result.

Continued poking at unknown flows in the July trace data. Added protocols for Final Fantasy XIV and Facebook Messenger. Noticed that we are still having issues with the vDAG pipe on the probe that services wdcap dropping packets so our captures are sometimes missing packets. Moving IP encryption off onto wraith seems to have helped with this, but is not an ideal solution.




Short week after taking leave on Monday and Tuesday.

Spent most of my remaining week looking at some new captures I took using the upgraded Probe. The main aim was to see whether there were any new protocols that libprotoident should be able to identify. Managed to find a handful of new protocols: Facebook Zero, Forticlient SSL VPN and Discord, as well as made some improvements to the rules for existing protocols (including the AMP throughput test!).

Most of my time was actually spent unsuccessfully hunting down what appears to be a new Chinese P2P protocol, which is a shame because it was contributing a very large amount of unknown traffic in my sample dataset.

Using BSOD on the live traffic feed also allowed me to spot a student that was doing vast quantities of torrenting on the campus network (which Brad reported to ITS) and our WITS FTP server being hammered with tons of download attempts from China. Fair to say, we've gotten some good milage of the upgraded Probe already.

Fixed a couple of outstanding bugs in amp-web. Should be ready to push some new packages out to skeptic and lamp early next week now.




Ported my event group pruning code from amp-web to a separate daemon that runs as part of netevmon. Rather than tweaking the event groups prior to displaying them on the dashboard, the daemon periodically fetches the most recent event groups from the database and checks for any redundancies that can be pruned. If any are found, the database itself is updated in place.

The benefits of this approach over the amp-web approach are that we can save on space in the event database and we don't need to do the full redundancy processing every time someone loads the dashboard. The one downside is that any merges are effectively permanent so I have to be very careful about testing my redundancy checks before rolling them out live.

Found and fixed some more Influxdb memory problems when using the matrix. Most of the problems related to us using the last() function, which for some reason can result in Influxdb loading the whole table into memory. I've managed to rewrite the queries that used last() so that they don't require anywhere near as much memory (or processing time) so tooltips, in particular, should be a lot faster to process and less likely to push the server into swap.

Got the waikato capture point back up and running after its disks were replaced on Thursday. Used it to demo BSOD to various visitors who were here for the CSC.




Continued reading over Stephen's thesis.

Further refined my event dashboard improvements. Added an algorithm that should recognise redundant event groups based on ASNs that the groups have in common with other groups that occur at the same time. This allows us to get rid of a large number of the vague UoW-REANNZ-AARNet, REANNZ-AARNet and UoW-REANNZ groups that were cluttering up the dashboard on prophet. Found and fixed a few bugs with the self-updating dashboard that were causing event groups to disappear or appear in the wrong order.

Added a working summary graph to the traceroute path map view, with the added benefit of making the selector appear and actually work for this graph.

Continued to battle with InfluxDB's memory usage on prophet. Experimented with tuning a variety of configuration options to try and avoid some of the surges that we occasionally see. Since these surges usually eventually result in the OOM killer being invoked, we need to be able to better control the memory usage before we can consider rolling InfluxDB into production.




Spent most of my week looking into methods for reducing some of the redundant event groups that appear on the amp-web dashboard. Came up with an algorithm for detecting smaller groups that are already covered by one large group, as well as one for detecting when a large group should be removed in favour of the smaller sub-groups.

Implemented my techniques on prophet, but the range of event groups that I get are a bit limited to be sure that everything is working correctly. Next week I may look into grabbing a copy of skeptic's event database to see how well things work on a more diverse set of event groups.

Spent some time reading over Stephen's revised thesis.




Back into it after a couple of weeks spent moving house.

Worked with Brendon to get nntsc, ampy and amp-web upgraded on skeptic. Also got netevmon running on skeptic so we now have event detection running on the public AMP mesh.

While I was away, InfluxDB ran out of memory and died on prophet. Trying to catch up on the backlog of data kept causing InfluxDB to use ridiculous amounts of memory so I had to spend a decent chunk of my week chasing the cause down. At this point, my biggest wish is that someone will add sensible memory management to InfluxDB.

Did a bit of preliminary writing of a possible paper on NNTSC. Organised some of my thoughts on network measurement ecosystems and turned them into a blog post.




We've been doing a lot of collaborative work with our ISP partners lately and one thing that has become increasingly apparent to me is the disconnect between what ISPs expect from measurement / monitoring software and what researchers typically have the time and energy to implement.

More specifically, researchers are very good at developing new or improved measurement techniques but they are not so great at developing the necessary infrastructure around the measurements to make it easy for ISPs to deploy and use the new techniques in a production environment. As a result, the ISPs tend to fall back on tried and true monitoring software (e.g. Smokeping) even though our conversations with operators suggest that they would prefer more than just the simple metrics and graphs that such tools provide.




Finished adding concurrent postgres-influx support to NNTSC, so now we should be able upgrade existing deployments to use influx without having to worry about migrating the existing data from one database to another.

Added an event feedback system to amp-web so that users can click on events and tell us whether the event was useful or not and provide some reasons why that was the case. Hopefully I can use this data to make some tweaks to netevmon and improve the quality of our event detection.

Started reading Stephen's thesis.




Developed a new 'stacked jitter' graph to amp-web for showing the range of packet delay variation seen by the amp-udpstream test. Also added UDPStream data as an option for the latency and loss matrices.

Started working on a transition scheme that will allow an influx-based NNTSC to fetch old data from a postgresql database if required. The idea is that this will save us having to deal with migrating the postgres data over to influx when we upgrade our existing deployments to use influx, while still making the old data queryable.




Made some progress on the InfluxDB memory issues we were having when catching up on old data. Now we are a lot less likely to drive the machine into swap, at the cost of taking a bit longer for backfilled data to be aggregated. Part of the problem was caused by my fix last week for the change in behaviour for the first() and last() aggregation functions in Influx 0.11 -- I've put in a new hacky fix but I'm basically waiting for Influx 0.13 which will hopefully provide us a way to get the old behaviour back.

Found another weird bug in Influx where if we query for certain streams, then sometimes a result row will get split into two "half-rows". This was messing with our querying code in NNTSC which assumes that the database will return only complete rows, so I've had to add extra code to deal with this possibility.

More influx issues: we aren't allowed to perform aggregation on the timestamp column in an Influx table, which was breaking our loss calculation for DNS -- we were using count(timestamp) to determine how many DNS requests we had sent as this was the only non-NULLable column in the DNS data table. Instead, I've had to add an extra "requests" column to the DNS data table so that we have an explicit count available in our aggregated data.

Lots of little fixes on the website. The changes to modals to bootstrap 3.3 are continuing to have a number of interesting flow-on effects, such as the "add new series" modal no longer working after the first time it is used. Added an AS path tab to latency and loss graphs that are only showing a single series, as we've often seen some interesting change and wondering whether the path has changed at the same time. Also fixed an issue where the last datapoint was often not visible on the graphs.

Finally, submitted my unexpected traffic paper to IMC on Thursday. Fingers crossed.