The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

  • My badges

    Mastodon

  • Twitter Updates

  • My Flickr Stream

    20140508-Delphi-2007--Project-Options--Cannot-Edit-Application-Title-HelpFile-Icon-Theming20140430-Fiddler-Filter-Actions-Button-Run-Filterset-now20140424-VMware-Fusion-6.0.3.-no-reclaimable
    More Photos

  • Pages

  • All categories

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 1,862 other subscribers

Archive for the ‘Linux’ Category

« Previous Entries
Next Entries »

Mariuz’s Blog: Understanding Debian: The Universal Operating System

Posted by jpluimers on 2020/12/25

Blast from the past: [WayBack] Mariuz’s Blog: Understanding Debian: The Universal Operating System.

Small image below; large image: [WayBack] infographic_debian.png.

Via [WayBack] Adrian Marius Popa – Google+

–jeroen

Posted in *nix, Debian, Linux, Power User | Leave a Comment »

mkcert: valid HTTPS certificates for localhost (Windows/Mac/Linux) — a short blog post about it, by FiloSottile

Posted by jpluimers on 2020/12/21

Cool: [WayBack] Filippo Valsorda on Twitter: “mkcert: valid HTTPS certificates for localhost — a short blog post mkcert now that it’s almost done 🔒 “

Blog post: [WayBack] mkcert: valid HTTPS certificates for localhost:

The web is moving to HTTPS, preventing network attackers from observing or injecting page contents. But HTTPS needs TLS certificates, and while deployment is increasingly a solved issue thanks to the ACME protocol and Let’s Encrypt, development still mostly ends up happening over HTTP because no one can get an…

Code: [WayBack] GitHub – FiloSottile/mkcert: A simple zero-config tool to make locally trusted development certificates with any names you’d like.

It is cross platform and works way better than good old Windows makecert (which is from the 2000’s era: [Archive.is] Public Key Infrastructure: Second European PKI Workshop: Research and … – David Chadwick, Greece) European PKI Workshop: Research and Applications (1st : 2004 : Samos Island – Google Books).

Related:

–jeroen

Read the rest of this entry »

Posted in *nix, Apple, Encryption, HTTPS/TLS security, Linux, Mac OS X / OS X / MacOS, Power User, Security, Windows | Leave a Comment »

RAMBOOT – booting Linux into a RAM disk…

Posted by jpluimers on 2020/12/14

Interesting as this should work for other Linux distributions as well: [WayBack] RAMBOOT – How to booting Debian into a RAM disc for speed and silence. How to RAMBOOT. It’s a poor man’s SSD, or a way to get SSD benefits on a laptop … – Isaac Kuo – Google+

Via: [WayBack] RAMBOOT – How to booting Debian into a RAM disc for speed and silence. How to RAMBOOT. It’s a poor man’s SSD, or a way to get SSD benefits on a laptop … – Jürgen Christoffel – Google+

Covers: [WayBack] RAMBOOT is an initrd hack that loads the entire OS partition in RAM, making it run like an extremely fast SSD, at the expense of perhaps 1.5+GB of RAM.

A quick search revealed these:

–jeroen

Posted in *nix, *nix-tools, Linux, Power User | Leave a Comment »

How To Use Journalctl to View and Manipulate Systemd Logs | DigitalOcean

Posted by jpluimers on 2020/11/05

For my link archive because of the tips: [WayBack] How To Use Journalctl to View and Manipulate Systemd Logs | DigitalOcean

–jeroen

Posted in *nix, *nix-tools, journalctl and journald, Linux, Power User | Leave a Comment »

Linux Find Out What Process Are Using Swap Space – nixCraft

Posted by jpluimers on 2020/10/26

Some interesting tips at [WayBack] Linux Find Out What Process Are Using Swap Space – nixCraft

  • pidof
  • pgrep
  • grep –color VmSwap /proc/####/status
  • awk the same information
  • doing the same in loops
  • smem
  • top

Via: [WayBack] Want to find out what process are using swap space? Useful to debug and optimize your app. … – nixCraft – Google+

–jeroen

Read the rest of this entry »

Posted in *nix, Linux, Power User | Leave a Comment »

Some postfix notes

Posted by jpluimers on 2020/10/15

Postfix has documentation on primary MX and secondary MX, but not on tertiary MX.

If the primary MX is down, you have a series of secondary MX and tertiary MX that configured the same way, MX DNS priority for primary, the series of secondary MX and tertiary MX have increasing numbers, and the primary MX goes down, then senders can get “too many hops” as secondary and tertiary MX are looping.

I had a hard time finding a good and easy solution as these queries do not return many meaningful results:

Here are some links that helped getting this solved:

  • [WayBack] Postfix Frequently Asked Questions: What does “Error: too many hops” mean?

    Short answer: this message means that mail is probably looping. If you see this after you turned on Postfix content filtering, then you have made a mistake that causes mail to be filtered repeatedly. This is cured by appropriate use of content_filter=, header_checks=, and body_checks=.

    Long answer: the message has too many Received: message headers. A received header is added whenever Postfix (or any MTA) receives a message. A large number of Received: message headers is an indication that mail is looping around.

    Side comment: email uses the opposite of the technique that is used to avoid IP forwarding loops. With IP, the sender sets a TTL (time to live) field in the IP header. The field is decremented by each router. When the TTL reaches zero the packet is discarded and an ICMP error message is returned to the sender.

  • [WayBack] Error: too many hops (in reply to end of DATA command) · Issue #713 · mail-in-a-box/mailinabox · GitHub

    In case you or anyone else was/is wondering about the mydestination = localhost thing, the reason it has to be set to just localhost is because MIAB uses Postfix’s “virtual domain hosting” (http://www.postfix.org/VIRTUAL_README.html) support. Per the documentation for mydestination at http://www.postfix.org/postconf.5.html#mydestination:

    Do not specify the names of virtual domains – those domains are specified elsewhere. See VIRTUAL_README for more information.

    (in the context of MIAB every domain is a virtual domain).

In my case a series of these:

Received: from mwgp.xs4all.nl (mwgp.xs4all.nl [80.101.239.92])
    by fiber24315337242.heldenvannu.net (Postfix) with ESMTP id 26395200FE
    for <jeroen@pluimers.com>; Fri, 29 Jun 2018 11:01:02 +0200 (CEST)
Received: from fiber24315337242.heldenvannu.net (unknown [37.153.243.246])
    by mwgp.xs4all.nl (Postfix) with ESMTP id 077A5E937
    for <jeroen@pluimers.com>; Fri, 29 Jun 2018 11:01:02 +0200 (CEST)

Specifying the transport will likely help me solve this problem:

This all came down to editing /etc/postfix/transport adding lines for each relayed domain like this one:

example.org    smtp:[mx-a-record.example.org]

Lines like it direct to use the smtp transport and use a specific host (normally, the relay transport is being used).

After this:

# postmap /etc/postfix/transport
# rcpostfix reload

I choose not to configure [WayBack] Postfix Configuration Parameters: relay_recipient_maps, but might if I had an automated way of replicating lists of valid (and invalid) users.

Another option was confirmed at [WayBack] Software-update: Postfix 3.4.0 / 3.3.3 / 3.2.8 / 3.1.11 / 3.0.15 – Computer – Downloads – Tweakers by [WayBack] menocchio. Thanks!

Dat is volgens mij eenvoudig op te lossen met relay_transport of transport_maps. Zie ook: Postfix transport table format.

Daarmee dwing je de secondary servers de mail altijd af te willen leveren bij de primary server (en dus niet bij een andere secondary). En als de primary niet online is, dan wacht ie netjes tot dat wel het geval is :-)

Bijvoorbeeld:
relay_transport = smtp:[primarymx.domain.tld]

Likely relevant: [WayBack] The Book of Postfix

Maybe relevant in the future:

Found on my hunt for the above:

Try not to make typo’s: [WayBack] postfix appears not finding MX records or host names from DNS

Interesting thought, but not sure how smart SPAM bots are now: [Archive.is] Spam relaying through secondary MX… – Google Groups

To archive this:

  1. Rename from
  2. To
  3. Then save in Archive.is

–jeroen

Posted in *nix, Communications Development, Development, DevOps, DNS, etckeeper, Infrastructure, Internet, Internet protocol suite, Linux, Power User, SMTP | Leave a Comment »

Rebooting a Linux server unattended – twm’s blog

Posted by jpluimers on 2020/09/21

[WayBack] Rebooting a Linux server unattended – twm’s blog:

/sbin/shutdown -r now

Simple, but I keep forgetting where Linux has short/long command options and short/long verbs.

–jeroen

Posted in *nix, *nix-tools, Debian, Linux, OpenShift, openSuSE, Power User, Raspbian, RedHat, SuSE Linux, Tumbleweed, Ubuntu | Leave a Comment »

On my list of things to figure out: how to force fsck with opensuse Tumbleweed on Raspberry Pi 3

Posted by jpluimers on 2020/09/11

Hopefully the below links will eventually get me further in figuring out how to force fsck with opensuse Tumbleweed on Raspberry Pi 3.

For now, I just reinstalled an SD card (my Mac didn’t support the file systems and I did not have time and equipment with me to mount it to another opensuse based device).

–jeroen

Posted in *nix, Linux, openSuSE, Power User, SuSE Linux, Tumbleweed | Leave a Comment »

Tracing a packet journey using Linux tracepoints, perf and eBPF | Yet another enthusiast blog!

Posted by jpluimers on 2020/08/21

As I need this one day: [WayBack] Tracing a packet journey using Linux tracepoints, perf and eBPF | Yet another enthusiast blog!

Via: [WayBack] Great read about bpf – Kristian Köhntopp – Google+

–jeroen

Posted in Linux, Power User | Leave a Comment »

Chromium/Chrome on opensuse Tumbleweed ARM notes

Posted by jpluimers on 2020/07/27

Somehow Firefox is available on ARM by default, but the crash recovery isn’t that awesome.

On my list of things to try is Chrome or Chromium. These links should help me find out if this is possible at all:

On Firefox crash recovery:

–jeroen

Posted in *nix, Chrome, Google, Linux, openSuSE, Power User, SuSE Linux, Tumbleweed | Leave a Comment »

« Previous Entries
Next Entries »