End of Semester 1 (2017-18) Report

By | January 22, 2018


During the first semester SUWS had three separate talks.  David Newman gave a talk about how VPNs can be used to build distributed networks and the experience using these as part of the SOWN project.  David Young (M0YAY) chaired a panel session about buying you first radio for new members.  Finally, Tyler (M0UAV) gave talk on how to start, develop and manage a project within SUWS.  Using the Powerpole Distribution and Morse sounder projects as exemplars.


Foundation and intermediate exams were run at the end of November, with 3 foundation and 1 intermediate candidates passing and becoming licenced. It is intended for the next batch of exams to be sat shortly before Easter vacation, possibly on Thursday 15th March or around then.

HF Yagi Refurbishment

The long-awaited HF Yagi refurbishment has also progressed. Refurbishment of the Yagi was completed in early November with testing shortly afterwards. The Yagi was found to have a good SWR on 15m, but required the use of a tuner on 10m and 20m to achieve a usable SWR. The RF traps require investigating using a VNA in order to identify which traps are faulty, however further testing should be done with an increased elevation of the yagi to avoid effects due to Earth proximity.


On the 6th of December, the club hosted the GB17YOTA callsign as part of the IARU Youngsters on the Air month. We made a number of contacts from SOME COUNTRIES on 20m.

2 x Sweden, 2 x Poland,2 x Russia, 1 x Hungary, 1 x Romania, 1 x Croatia

SOWN Zepler

As already discussed in an earlier post, just before the start of Semester 1, SOWN deployed a new SOWN Zepler node on the roof of Building 59 on Highfield Campus. Since then we have been able to get the SDRs running whose output can now be viewed on the Zepler SUWS WebSDR.  However, we have not made much progress on getting RADIUS authenticated Internet access working off either of the antennas for 802.11n on 2.4GHz and 802.11ac on 5.8GHz.  The latter we suspect is due to both the antenna and the connectors on the coax cable it is connected to looking somewhat the worse for wears, after the best part of a decade on the roof of the Zepler building.  With the former, despite a couple of us spending around an hour trying to connect we got little more than a few packets through before being disconnected.  Although the signal on 802.11n is not as strong as we would like, we suspect the issue is more like a software configuration one with DHCP or RADIUS.

SOWN Zepler Installation 5

View of SOWN Zepler from the ground

Other SOWN projects

There has been a lot of developments on SOWN in the past few months, beyond the deployment of the new SOWN Zepler.  Over Christmas, we upgraded our most important server (sown-auth2), which was a bit nerve-wracking, as we had been putting off upgrading it for a while and knew there were a number of bespoke features that might not work on an upgraded system.  However, as we had extensive experience of server upgrades for Ubuntu Linux, this went a lot more quickly and smoothly than feared.

Early in the semester, a security vulnerability, know as KRACK was discovered with was discovered with WPA2, which SOWN(at)Home nodes uses to securely send data between the node and those using it.  We produced an OpenWRT firmware upgrade for our AR150, which we have rolled out to our nodes in the field.  As well as working on this upgrade, David (M0YAY) and Kajusz (M0PWN) have been working on producing a firmware for the GL-MiFi node, which has an built-in battery and 3G/4G module meaning it can be a completely wireless node.

For some time SOWN has had IPv6 on its servers but we have now started to roll this out to SOWN(at)Home nodes.  This is being done in two different ways.  For node hosts that already have IPv6 on their home networks, nodes can be configured to use part of their IPv6 subnet.  Otherwise, nodes can be configured to use part of the SOWN subnet.  Up until recently, although SOWN had been allocated a /56 (272 addresses) it had only a /64 (264 addresses) actually routed to SOWN’s gateway server.  Although both of these sound like a lot of addresses, a /64 is the smallest easily allocatable subnet, so this was used by our servers.  Now we have 256 /64 subnets available to us, this is enough to deploy over 100 SOWN(at)Home nodes with one subnet for its VPN connection and one for its wireless interface, to which users connect.

In the course of the University routing SOWN its whole /56 subnet, they suggested we be Guinea pigs for IPv6 routed via their core routers, rather than ECS’s IPv6 infrastructure.  This allowed us to feedback user requirements for IPv6, as well as compare behaviour of devices on the old and new infrastructure to advise iSolutions (the University’s IT support department) about how to mitigate issues on the old infrastructure.

Shortly after this, we moved SOWN’s IPv6 subnet from (65,536 addresses) to  The reason for this change was to allow SOWN traffic to be routed to and from the rest of the University network. The original subnet could not be routed as it was already in use.  By having a routed subnet, this will allow SOWN to cease having a separate trunked VLAN as well as the SOWN VLAN.

Plans for the semester 2

For SOWN, as already mentioned, the signal strength for 802.11ac on SOWN Zepler was basically non-existent, therefore we would like to design and built a three antenna MIMO array to gives us the best possible signal strength.  This project may take a while to come to fruition, as acquiring the equipment and building and testing with our existing Archer C7 will take a while and then we need to organise another trip back up to the roof of Zepler.

Also for SOWN, we plan to continue firmware development to integrate the GL-MiFi firmware with SOWN’s admin site and node configuration manager.  We also have work planned to support traffic shaping for our non-eduroam SOWN(at)Home nodes.  On the SOWN network itself, we still need to make a few changes to maintain public IPv4 addresses for certain SOWN servers, whilst only connecting the servers on the SOWN VLAN.

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