News items for tag english - Koos van den Hout

2021-03-11 Sendmail 8.15.2 in Ubuntu 20.04 not even trying IPv6 1 month ago
I needed a virtual machine with ubuntu so I did the base installation and also configured unattended-upgrades and sendmail to get the results. But I noticed after a while I never saw any mail from that machine.

Problem soon found:
mailer=relay, pri=30131, relay=postbode.idefix.net. [82.95.196.202], dsn=4.0.0, stat=Deferred: Connection timed out with postbode.idefix.net.
The machine wasn't even trying to reach the mailserver over IPv6! On the internal network with servers it will fail over IPv4 because of the portforwarding rule for the port from the outside IP to the mailserver but I never expected an internal machine to try IPv4.

Somehow this seems default for sendmail 8.15.2 in Ubuntu 20.04. I could find someone else asking this: No IPv6 outbound from Sendmail starting with 20.04 but no answers how/why.

At first I suspected systemd-resolved as the old saying goes that all sendmail problems are caused by DNS. But disabling that didn't fix the problem.

I now have the IPv6 address hardcoded in the configuration, that works.
dnl FEATURE(`msp', `postbode.idefix.net', `25')
FEATURE(`msp', `[2001:980:14ca:1::23]', `25')
I also found out the option ResolverOptions=+WorkAroundBrokenAAAA was set but not causing this.

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2021-03-07 Chasing amateur radio awards 1 month ago
A fun bit of amateur radio is the possibility to get awards for making contacts. There are awards like the American Radio Relay League DX century club for making contacts with at least 100 'countries' or the awards linked to summits on the air which are awards for making contacts from or to a number of mountain tops.

There are also awards for making contacts with special event stations. Currently there are several special event stations on the air celebrating 200 years of Greek independence. So far I have found two award options linked to those stations, but there may be more.

Special event stations are usually linked to a special event, such as this historic event for Greece. It is a way to notice things in history or other events that you normally wouldn't notice.

Special Event Station (SES) series as SX9A, SX8A, SX7A, SX6A, SX5A, SX4A, SX3A, SX2A and SX1A to celebrate the 200th anniversary of Hellenic War of Independence against Ottoman Turks. and The Greek Revolution of 1821 We celebrate the 200th anniversary of Hellenic War of Independence Special Event Call 01-31 March 2021 and 200 Years of Greek Independence Award.

It's a good thing they all have websites where you can see your progress and download the digital awards.

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2021-03-06 Digging for more entropy 1 month ago
Looking at the newest graphs I created with grafana of system statistics I noticed the available entropy was still getting dangerously low from time to time on the system that runs the home server. For some reason this system has no available hardware random number generator. Even after the earlier changes to add more sources of randomness it was sometimes dropping low, especially during dnssec signing operations.

This does mean that the encryption processes for TLS in the webservers may also get delayed. Which is really not what I want.

Time to update settings on randomsound and haveged: I want a minimum of 2048 bits of available entropy. Sofar, this seems to have the desired effect.

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2021-03-03 Checking the TLS setup for my webservers 1 month ago
Encrypt all the things meme I'm currently following the course The Best TLS and PKI Training Course in the World and learning even more about the workings of encryption, TLS and certificates.

One of the things I learned is to balance security with performance. And I directly used this new insight on my own webservers. The connection which brought you this page from https://idefix.net/ is still encrypted but I saved a few milliseconds on the encrypted setup by switching from a big (4096 bit) RSA private key to a 384 bit ECDSA key which are comparable in cryptographic strength. But the calculations with the ECDSA key are less CPU intense. And yes, I have statistics on page loading times before and after the changeover of the key.

It was a good moment to change private keys anyway, the old keys were more than a year old.

This is one of those areas where I like having my knowledge hands-on. Actually understanding what is happening and why.

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2021-03-01 Updating my statistics gathering 1 month ago
Grafana dashboard sample For years and years I have been using rrdtool to gather and graph statistics at home. I started gathering home temperatures around 2008 but I see NTP statistics gathering from 2003 and my last mrtg graphs were created in October 2002. So that suggests I've been using rrdtool since that date.

Anyway, I'm looking at newer options. After some asking around I installed influxdb and started gathering data. I adjusted some of my data gathering scripts around rrdtool to also put the data in influxdb.

The easiest data to gather and graph was the load average, available entropy and number of processes for a number of systems at home. So that dashboard has been built and allows selection of the wanted computer.

My first conclusion is just collecting data and thinking what kind of graphs to create later is a lot easier with influxdb. With rrdtool the round robin database is designed around the graphs you want. In this case I just start gathering data and when data has come in start playing with possible graphs from that data.

The next challenge is to set the rules for maintaining the old data. One of the triggers to look at other options was that I was at the end of a nearly 11-year cycle of stored temperatures in rrdtool, and I wanted to keep that history if possible.

I don't have to keep every measurement forever, but with storage being cheap I think I will keep daily averages forever when this is 'production'.

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2021-02-27 Ordered parts for an NTP ham clock 1 month ago
Today the Electron magazine of the Veron amateur radio club came in, the March 2021 Veron Electron (Dutch).

As I was browsing the magazine and reading articles I came across an article about building an NTP ham clock, consisting of an ESP32 module and a TFT LCD display, and the rest is all in software.

I directly wanted to build this, as this combines two of my interests: amateur radio and NTP time synchronization. It displays both the local time and the UTC time on the TFT display, just like PyHamClock does on my screen.

The article is based on the same project at W8BH projects which gives me a good descriptive pdf.

So I ordered an ESP32 module and ILI9341 TFT LCD display from an aliexpress seller and now I wait, because this will take about a month.

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2021-02-20 Maintaining old URLs with parameters 1 month ago
In looking for something different I noticed requests for old urls for rss.php urls on a site. But that site was rewritten in a different programming language and I use a generic .cgi extension.

I had to look up how to do redirects with paramaters again because a RewriteRule directive in apache normally only uses the url, not the parameters. The page Redirecting and Remapping with mod_rewrite - Apache HTTP Server Version 2.4 gave me some hints, and I ended with:
    RewriteCond "%{QUERY_STRING}" "(.+)"
    RewriteRule "^/rss.php" /rss.cgi?%1 [R]
Which does exactly what I want.

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2021-02-16 Finally Armenia confirmed in amateur radio 2 months ago
Getting new countries in the log is one part, getting those countries confirmed is another.

Armenia had been 'evading' me for a few years because there aren't a lot of active radio amateurs in that country and the first ones I had contacts with decided to want money for a QSL card or digital confirmation. I decided to keep trying and in December 2020 I got a new station in the log: EK3GM and that station confirmed via Logbook of the World. So now I have that country confirmed, making the total 127 countries contacted, 120 confirmed via Logbook of the World.

Update 2021-02-17: And being active in the CQ WPX RTTY contest last weekend caused another confirmed country that I have been 'chasing' for a while: Tunesia. Contest station 3V8SS was very active, I got in the log and now I have 121 countries confirmed via LoTW.

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2021-02-15 I participated in the PACC 2021 contest and in the CQ WPX RTTY 2021 contest 2 months ago
A busy weekend with multiple radio contests going on. And a lot of other stuff in the weekend too so not much time to actually participate! I came to both contests fully unprepared and without much space in the weekend planning for butt in chair time.

First was the Dutch PACC contest where I participated Saturday afternoon and in the last 20 minutes of the contest Sunday morning. In this contest I made 21 contacts: 14 in morse and 7 in phone.

The second contest was the CQ WPX RTTY contest 2021 which is a 48 hour contest, which allowed me to start after I finished in the PACC and get stations in the log Sunday afternoon and evening. In this contest I made 70 contacts.

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2021-02-15 Snow over the Netherlands satellite image 2 months ago
Satellite image of the Netherlands 2021-02-13 with snow cover. I acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Observing System Data and Information System (EOSDIS).
Satellite image of the Netherlands 2021-02-13 with snow cover.
I acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Observing System Data and Information System (EOSDIS).
In the weekend of 6 and 7 February 2021 the Netherlands got covered in snow and temperatures dropped to -10 degrees Celcius. In the week after that weekend temperatures stayed low and clear skies made for nice weather for outdoor skating and other wintersports. I was reminded of being on wintersport holiday.

I just had to look up the available images from the NASA Global Imagery Browse Services (GIBS) and found a great image from 13 February 2021. Click for more pixels!

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IPv6 check

Running test...
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Meningen zijn die van mezelf, wat ik schrijf is beschermd door auteursrecht. Sommige publicaties bevatten een expliciete vermelding dat ze ongevraagd gedeeld mogen worden.
My opinions are my own, what I write is protected by copyrights. Some publications contain an explicit license statement which allows sharing without asking permission.
Other webprojects: Camp Wireless, wireless Internet access at campsites, The Virtual Bookcase, book reviews
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