Often connections are TCP based, but sometimes UDP is all you have to test with, so I was quite surprised that testing that was quite forward. The solutions by [Wayback/Archive] How to Do a UDP Ping in Linux works on any platform where you can have nmap or netcat on installed (which by now is almost all platforms including Windows):
Archive for the ‘*nix-tools’ Category
How to Do a UDP Ping in Linux
Posted by jpluimers on 2026/01/07
Posted in *nix, *nix-tools, Apple, BSD, Mac OS X / OS X / MacOS, netcat, nmap, Power User, Windows | Leave a Comment »
See a List of All Wi-Fi Networks a Mac Has Previously Connected To
Posted by jpluimers on 2025/12/24
[Wayback/Archive] See a List of All Wi-Fi Networks a Mac Has Previously Connected To
n modern versions of Mac OS, like macOS Mojave, Catalina, Sierra, OS X El Capitan, and Yosemite, you can shorten the syntax considerably as so:defaults read /Library/Preferences/SystemConfiguration/com.apple.airport.preferences |grep SSIDStringIn prior versions of Mac OS X, you can opt for the same as the above command, or use the lengthier string below with heavy regex:
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Posted in *nix, *nix-tools, Apple, bash, bash, Development, Mac, Mac OS X / OS X / MacOS, MacBook, Power User, Scripting, Software Development | Leave a Comment »
When you get an error 103 establishing an SFTP
Posted by jpluimers on 2025/12/10
A while ago I got an error 103 using both Beyond Compare. That did not whos the connection log or error reason, but WinSCP did: it mentioned unexpected output during the logon.
I got reminded that I had already solved this error before via [Wayback/Archive] SSH login works but SFTP login doesn’t – Server Fault (thanks [Wayback/Archive] qreon and [Wayback/Archive] Paulus):
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Posted in *nix, *nix-tools, bash, bash, Beyond Compare, Communications Development, Development, Internet protocol suite, Power User, Scripting, SFTP, Software Development, SSH, TCP, Windows, WinSCP | Leave a Comment »
Some notes on running Postfix inside a docker container
Posted by jpluimers on 2025/11/14
The plan was to run a Postfix secondary MX inside a docker container.
Below are many links that might help me to get that going.
For now, I think this is the shortlist of solutions to try:
- Docker Mailserver
- Mailcow
- Mailu
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Posted in *nix, *nix-tools, Cloud, Communications Development, Containers, Development, Docker, Infrastructure, Internet protocol suite, Kubernetes (k8n), postfix, Power User, SMTP | Tagged: 254, 29, 52, 787, DMARC, domains, set | Leave a Comment »
roehling/postsrsd: Postfix Sender Rewriting Scheme daemon
Posted by jpluimers on 2025/11/12
This finally made me perform the (long overdue) migration from Sendmail to Postfix:
The Sender Rewriting Scheme (SRS) is a technique to forward mails from domains which deploy the Sender Policy Framework (SPF) to prohibit other Mail Transfer Agents (MTAs) from sending mails on their behalf. With SRS, an MTA can circumvent SPF restrictions by replacing the envelope sender with a temporary email address from one of their own domains. This temporary address is bound to the original sender and only valid for a certain amount of time, which prevents abuse by spammers.
[Wayback/Archive] roehling/postsrsd: Postfix Sender Rewriting Scheme daemon
Via a long queste to figure out why Gmail every now and then bounces forwarded messages because of Sender Policy Framework (SPF). Below are a few of the links that brought me here in mostly reverse order, but first some links that should help me further on the topic of Postfix virtual aliases.
The sendmail setup had some features not covered below (like a catch-all forward for email to addresses virtual domains not covered by a virtual alias) which I hopefully can cover later.
One thing learned both over the past decades and related postfix material: use separate servers or containers for each of your functions. So do not mix web-hosting, outgoing mail, incoming mail, fail2ban and others on the same server.
Links:
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Posted in *nix, *nix-tools, Communications Development, Development, Internet protocol suite, postfix, Power User, sendmail, SMTP | Tagged: Reload | Leave a Comment »
LinuxCND: The Raspberry Pi that ships other Raspberry Pis – Pi Australia
Posted by jpluimers on 2025/11/11
Cool practical application of LinuxCNC: [Wayback/Archive] The Raspberry Pi that ships other Raspberry Pis – Pi Australia
LinuxCNC controls CNC machines. It can drive milling machines, lathes, 3D printers, laser cutters, plasma cutters, robot arms, hexapods, and more.
Via [Wayback/Archive] Frans van Berckel on Twitter: “@geerlingguy So, there is a Raspberry Pi, that ships other Raspberry Pis?”
–jeroen
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Posted in *nix, *nix-tools, Development, Hardware Development, Linux, Power User, Raspberry Pi | Leave a Comment »
GitHub – louislam/uptime-kuma: A fancy self-hosted monitoring tool
Posted by jpluimers on 2025/11/05
As promised yesterday¹ because “what’s an open source project without its status page” (and some commercial vendors cough Embarcadero cough could highly benefit from this):
[Wayback/Archive] GitHub – louislam/uptime-kuma: A fancy self-hosted monitoring tool.
Some links (so you can try it for yourself):
- [Wayback/Archive] CryptPad Status (from yesterday’s blog post¹)
- [Wayback/Archive] Uptime Kuma docker site to try yourself
- [Wayback/Archive] Uptime Kuma Demo (starting by choosing a language – many – and database – MariaDB/MySQL or SQLite)
- [Wayback/Archive] Uptime Kuma Status
- [Wayback/Archive] Home · louislam/uptime-kuma Wiki · GitHub
- [Wayback/Archive] uptime-kuma/src/components/notifications at master · louislam/uptime-kuma · GitHub – I like this vast amount of integrations. Some commercial vendors could learn from this.
--jeroen
¹ GitHub – cryptpad/cryptpad: Collaborative office suite, end-to-end encrypted and open-source.
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Posted in *nix, *nix-tools, Development, JavaScript/ECMAScript, Monitoring, Power User, Scripting, Software Development, TypeScript, Vue.js | Leave a Comment »
GitHub – cryptpad/cryptpad: Collaborative office suite, end-to-end encrypted and open-source.
Posted by jpluimers on 2025/11/04
Google Docs alternative for self-hosting or hosted usage: [Wayback/Archive] GitHub – cryptpad/cryptpad: Collaborative office suite, end-to-end encrypted and open-source.
The project started last month 12 years ago in 2014 as the “realtime collaborative visual editor with zero knowlege server” with the commit [Wayback/Archive] and so it begins · cryptpad/cryptpad@1508c7b · GitHub.
Via¹: [Wayback/Archive] Dr. Christopher Kunz: “I’m currently testing Cryptpad for collaborative working.…” – chaos.social
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Posted in *nix, *nix-tools, Cloud, CSS, Development, Google, GoogleDocs, HTML, HTML5, Infrastructure, JavaScript/ECMAScript, Monitoring, Power User, Scripting, Software Development, TypeScript, Web Development | Leave a Comment »
i-am-shodan/USBArmyKnife: USB Army Knife – the ultimate close access tool for penetration testers and red teamers.
Posted by jpluimers on 2025/09/30
Now that I got pointed to this twice (see “Via” below), I need to get one so I can play with it: [Wayback/Archive] GitHub – i-am-shodan/USBArmyKnife: USB Army Knife – the ultimate close access tool for penetration testers and red teamers.
Via:
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Posted in *nix, *nix-tools, Blue team, Bluetooth, Development, Encryption, ESP32, Hardware, Hardware Development, Hardware Interfacing, Home Audio/Video, HTTPS/TLS security, Infosec (Information Security), Network-and-equipment, Power User, Red team, Software Development, WiFi, Wireshark | Tagged: USBArmyKnife | Leave a Comment »
bash alias to decode email Quoted-Printable stdin data
Posted by jpluimers on 2025/09/25
Perl isn’t my strength, so I was glad to find the below links that inspired me to add this bash function to my profile decoding Quote-Printable email data (for instance used by sendmail and postfix to store SMTP message files):
# https://superuser.com/questions/1452249/fix-revert-wrong-encoding-of-file function sendmail-decode-quoted-printable-from-stdin() { perl -0777 -ne 'use MIME::QuotedPrint; print decode_qp($_)' }
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Posted in *nix, *nix-tools, bash, bash, Development, Perl, Power User, Python, Scripting, sendmail, Software Development | Leave a Comment »
The Wiert Corner - irregular stream of stuff 