Category: tagged

  • AF60-LR Ethernet Carrier Drop option missing

    Dealing with rain on a 60 GHz radio link can be tricky. It works flawlessly with high capacity in the Gbit range when the weather is nice. Once raindrops start pouring down the link will degrade to a point where it may drop the connection completely, all depending on precipitation level and radio frequency/channel selection.

    When running OSPF over such a wireless bridge there is no indication that the link has failed until the next “Hello” receives no answer from the neighbouring router and the “Dead Interval” is reached. At this point the link would be brought down by OSPF and assuming there are redundant paths, traffic would be routed through another part of the network to its final destination.

    The problem here is the long time the link is reported as being up by OSPF when it is really down. This means traffic is being sent through this dysfunctional path and getting nowhere for as long as the duration of the OSPF “Hello” plus “Dead Interval” timer. Of course one could decrease this timer to a bare minimum, however in a wireless network there could be some brief interference at times which usually would not last long enough for the user to notice. It also increases load on the routers and albeit minimally, the network itself due to the extra packets.

    What we really need is the same experience for the router as if the network cable was to be pulled out of its port socket. The OSPF process would immediately bring the interface down and the path would no longer exist in the OSPF topology database. Traffic would be routed without delay and any downtime via the redundant path. Here is where Ethernet Carrier Drop comes into the picture. As described by Ubiquiti itself in the info label:

    Carrier drop monitors your link and disables Ethernet interface in case downlink capacity drops below configured threshold.
    Port is disabled, if capacity remains below threshold for Carrier Down delay.
    Once capacity exceeds specified threshold for Carrier Up delay, port will be enabled.

    I needed a link consisting of a pair of Ubiquiti 60 GHz airFiber (AF60-LR) to use Ethernet Carrier Drop when rain faded the signal strength killing the connection. The pair runs in a Master & Station mode so wireless configuration is done in the Master and propagates to the Station. However I could not find the Ethernet Carrier Drop selector anywhere. Looking through all the setting pages revealed nothing, however I knew it was present in the firmware.

    Digging around I found a reference to the feature in the old 2021 2.5.0 firmware change-log:

    - Ethernet Carrier Drop is configured on the Station side of the link. When Station DL capacity drops below configured threshold, Ethernet port will be disabled. Management will be available only via wireless link.

    So there you go, the Ethernet Carrier Drop feature is actually in the Station and not the Master wireless settings page.

    I guess the logic behind it is that usually the Master peer is more centrally located in the network topology and the Station in the remote branch. One cannot access the device while the Ethernet port is disabled, so if done on the Master one could be locked out from doing any further configuration changes. Still, it is a bit curious the feature is not explained anywhere apart from in a four year old firmware change-log.

  • Firefox not opening mailto links in Flatpak Thunderbird

    Using Fedora Kinoite Thunderbird comes in a Flatpak. This caused me issues with mailto links in Firefox not opening Thunderbird’s new email window.

    Usually just setting Thunderbird as the default email client inside Thunderbird’s settings or KDE’s default applications would have worked. Even selecting Thunderbird inside the Firefox file handler applications settings would have done the job. However mailto links did nothing but open up the application selector in Firefox which did not work.

    The first two places were already set correctly (in Thunderbird and KDE) so not much more to do there. As I cannot directly select Thunderbird’s binary since it is a Flatpak, I tried to get Firefox to open the Flatpak binary instead and somehow customise the command being run.

    There was just no way to customise the command through its interface, unless I fiddled with handlers.json directly in my Firefox profile directory. I tried a few combinations and no dice. I was also still reluctant to believe that all other users would go through this mess just to get mailto links working which is such a basic feature.

    The most annoying part was that XDG actually returned Thunderbird as the default handler for mailto links:

    $ xdg-mime query default x-scheme-handler/mailto
    org.mozilla.Thunderbird.desktop

    But checking my ~/.config/mimeapps.list file revealed that there was no mailto handler defined. Adding the corresponding entries finally fixed the issue:

    [Added Associations]
    x-scheme-handler/mailto=org.mozilla.Thunderbird.desktop;

    [Default Applications]
    x-scheme-handler/mailto=org.mozilla.Thunderbird.desktop;

    Glad that I got it working but still not satisfied that this was really the way to go, so I decided to start from scratch.

    I went back to KDE’s System Settings>Apps & Windows>Default Applications>Email client. Despite having Thunderbird already selected I went and selected Other… instead. Here I could select Thunderbird again but interestingly there were more options:

    You will notice in my screen-shot the check-box stating “Remember application association for all files of type “x-scheme-handler/mailto“. This check-box once checked actually updates the same ~/.config/mimeapps.list file with the previous entries I mentioned earlier.

    So apparently this is an option which is not enabled by default when just selecting Thunderbird in the default applications list. Why not having mailto links working by default in KDE is a conundrum.

    I am sure there are edge cases not wanting mailto links to open the default email client, but I would assume the vast majority of users expect this behaviour of the default email client. What is the point otherwise of selecting a default application?

  • Human Avatar for Robohash WordPress plugin

    I was tired of the similar looking avatars offered for comments. When changing them in Settings>Discussion>Default Avatar I noticed there was a new one, Robohash.

    Robohash has further customisation options but unfortunately they were not available to select in the avatar configuration options of WordPress.

    Specifically I liked their “human” set which I think Robohash keep pretty low key as it was only referenced briefly in a single paragraph at the very end.

    No point it customising the WordPress core directly because of updates, so instead I created a plugin for others to enjoy:

    Human Avatar for Robohash

  • Post comment notification email woes

    After having done an upgrade of a very old WordPress install, notification emails were not arriving properly.

    Since this installation was originally set up almost two decades ago, back when emails were sent directly from the same hosting server to the MTA. Due to the level of spam this caused, emails nowadays have to be submitted through a proper mail system, not forgetting the fact that port 25 is now blocked at nearly all providers.

    I do run some mail servers myself, however I wanted something quick to move on so I decided to use Mailgun which I had an account with already. They actually provide their own Mailgun WordPress plugin so I was up and running as soon as the new DNS records had propagated. Emails started arriving immediately when I updated the Administration Email Address under Settings>General with the new email address. Great stuff!

    However I realised that a new comment would no longer trigger the comment notification email. Nothing in the logs of nginx revealed what could be happening. I needed to figure out if the emails were even generated, and if so, where did they get stuck.

    Luckily there is another plugin which logs each email sent by WordPress. Once I tested another comment and checked the plugin’s log page in WordPress, I immediately realised what the issue was. It was still being sent to the old administrator email address!

    Later I did spot that Mailgun’s own logs actually revealed the same data, but at the time in question I was under the impression that the emails never left WordPress.

    Now the mystery… why the heck was WordPress still using the previous email address from Administration Email Address? This field was updated and other admin notification emails were being received just fine.

    The issue when dealing with a self-hosted WordPress for oneself is that in the vast majority of cases, one is both the site administrator as well as the only user posting. Apparently the new comment notifications emails are only sent to the post author and not the site administrator. I had simply forgotten about the old email address under the posting user’s profile (Users>Profile)!

    Comment moderation emails on the contrary do go to both site administrator and post author.

    Do not forget to add or update your Gravatar profile with the new email address.