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Posted by jpluimers on 2023/02/28
[Wayback/Archive] Wireshark Cheat Sheet – Commands, Captures, Filters, Shortcuts
It is available both a huge [Wayback/Archive] jpg (2500×2096 pixels), so it already prints well on A5 or A4 sized paper for reference and as a [Wayback/Archive] PDF (so you can print it on even larger paper sizes).
Via: [Archive] Murdock (@Generic42) / Twitter in a DM.
–jeroen
Posted in *nix, *nix-tools, Communications Development, Development, Hardware, Network-and-equipment, Power User, Software Development, Wireshark | Leave a Comment »
Posted by jpluimers on 2023/01/26
Because of [Archive] PragmaticProgrammers on Twitter: “Helpful Unix trick: use script to log your session. …” / Twitter:
–jeroen
Posted in *nix, *nix-tools, ash/dash, bash, bash, Batch-Files, Development, Power User, Scripting, Software Development | Leave a Comment »
Posted by jpluimers on 2023/01/18
Since I’m on a series of interactive tutorial sites, yesterday’s The SQL Murder Mystery made me bump into a project by [Archive] Noah Veltman (@veltman) / Twitter: [Wayback/Archive] veltman/clmystery: A command-line murder mystery
There’s been a murder in Terminal City, and TCPD needs your help.
To figure out whodunit, you need access to a command line.
Once you’re ready, clone this repo, or download it as a zip file.
Open a Terminal, go to the location of the files, and start by reading the file ‘instructions’.
I did a quick [Archive] clmystery – Twitter Search / Twitter and found the first ever Twitter mention to be this one from 2013 (boy, have I been living under a stone <g>): [Archive] RoR Group on Twitter: “A command-line murder mystery (clmystery) …” / Twitter.
Cool things:
–jeroen
Posted in *nix, *nix-tools, Apple, Development, Interactive Tutorials, Learning/Teaching, LifeHacker, Linux, Mac OS X / OS X / MacOS, Power User, Software Development, Terminal | 2 Comments »
Posted by jpluimers on 2022/12/28
Years ago, I wrote Getting your public IP address from the command-line. All methods were http based, so were very easy to execute using cURL.
But then in autumn 2021, Chris Bensen wrote this cool little blog-post [Wayback/Archive] Chris Bensen: How do I find my router’s public IP Address from the command line?:
dig -4 TXT +short o-o.myaddr.l.google.com @ns1.google.com
At first sight, I thought it was uncool, as the command was quite long and there was no explanation of the dig command trick.
But then, knowing that dig is a DNS client, it occurred to me: this perfectly works when http and https are disabled by your firewall, but the DNS protocol works and gives the correct result:
# dig -4 TXT +short o-o.myaddr.l.google.com @ns1.google.com "80.100.143.119"
This added the below commands and aliases to my tool chest for *nix based environments like Linux and MacOS (not sure yet about Windows yet :), but that still doesn’t explain why it worked. So I did some digging…
dig -4 TXT +short o-o.myaddr.l.google.com @ns1.google.com
dig -4 TXT +short o-o.myaddr.l.google.com @ns1.google.com | xargs
alias "whatismyipv4_dns=dig -4 TXT +short o-o.myaddr.l.google.com @ns1.google.com | xargs"
dig -6 TXT +short o-o.myaddr.l.google.com @ns1.google.com
dig -6 TXT +short o-o.myaddr.l.google.com @ns1.google.com | xargs
alias "whatismyipv6_dns=dig -6 TXT +short o-o.myaddr.l.google.com @ns1.google.com | xargs"
Let’s stick to dig and IPv4 as that not having IPv6 (regrettably still) is the most common situation today:
# dig -4 TXT +short o-o.myaddr.l.google.com @ns1.google.com "80.100.143.119"
What it does is request the DNS TXT record of o-o.myaddr.l.google.com from the Google DNS server ns1.google.com and returns the WAN IPv4 address used in the DNS request, which is for instance explained in [Wayback/Archive] What is the mechanics behind “dig TXT o-o.myaddr.l.google.com @ns1.google.com” : linuxadmin.
Since these are TXT records, dig will automatically double quote them, which xargs can remove (see below how and why):
# dig -4 TXT +short o-o.myaddr.l.google.com @ns1.google.com | xargs 80.100.143.119
The DNS query will fail when requesting the Google Public DNS servers 8.8.8.8 or 8.8.4.4:
# dig -4 TXT +short o-o.myaddr.l.google.com @8.8.8.8 "2a00:1450:4013:c1a::103" "edns0-client-subnet 80.101.239.0/24"
Or, with quotes removed (the -L 1 ensures that xargs performs the quote-pair removal action on each line):
# dig -4 TXT +short o-o.myaddr.l.google.com @8.8.8.8 | xargs -L 1 2a00:1450:4013:c1a::103 edns0-client-subnet 80.101.239.0/24
This request is both slower than requesting the ns1.google.com server and wrong.
The reason is that only ns1.google.com understands the special o-o.myaddr.l.google.com hostname which instructs it to return the IP address of the requesting dig DNS client.
That 8.8.8.8 returns a different IP address and an additional edns0-client-subnet with less accurate information is explained in an answer to [Wayback/Archive] linux – Getting the WAN IP: difference between HTTP and DNS – Stack Overflow by [Wayback/Archive] argaz referring to this cool post: [Wayback/Archive] Which CDNs support edns-client-subnet? – CDN Planet.
ns1.google.com: any DNS server serving the google.com domainSince o-o.myaddr.l.google.com is part of the google.com domain, the above works for any DNS server serving the google.com domain (more on that domain: [Wayback/Archive] General DNS overview | Google Cloud).
Getting the list of DNS servers is similar to getting the list of MX servers which I explained in Getting the IP addresses of gmail MX servers, replacing MX record type (main exchange) with the NS record type (name server) and the gmail.com domain with the google.com domain:
# dig @8.8.8.8 +short NS google.com ns3.google.com. ns1.google.com. ns2.google.com. ns4.google.com.
The ns1.google.com DNS server is a special one of the NS servers: it is the start of authority server, which you can query using the SOA record type that also gives slightly more details for this server:
# dig @8.8.8.8 +short SOA google.com ns1.google.com. dns-admin.google.com. 410477869 900 900 1800 60
The difference between using NS and SOA records with dig are explained in the [Wayback] dns – How do I find the authoritative name-server for a domain name? – Stack Overflow answer by [Wayback/Archive] bortzmeyer who also explains how to help figuring out SOA and NS discrepancies (note to self: check out the check_soa tool originally by Michael Fuhr (I could not find recent content of him, so he might have passed away) of which source code is now at [Wayback/Archive] Net-DNS/check_soa at master · NLnetLabs/Net-DNS).
So this works splendid as well using ns4.google.com on my test system:
# dig -4 TXT +short o-o.myaddr.l.google.com @ns4.google.com | xargs 80.100.143.119
xargs removes outer quotes removal trick[Wayback/Archive] string – Shell script – remove first and last quote (“) from a variable – Stack Overflow (thanks quite anonymous [Wayback/Archive] user1587520):
> echo '"quoted"' | xargs quoted
xargsusesechoas the default command if no command is provided and strips quotes from the input.
Some notes are in [Wayback/Archive] How to get public IP address from Linux shell, but note the telnet trick now fails as myip.gelma.net is gone (latest live version was archived in the Wayback Machine in august 2019).
whatismyipv4='curl ipv4.whatismyip.akamai.com && echo' It’s a quite a bit shorter than the dig construct in your post (;”–jeroen
Posted in *nix, *nix-tools, Apple, bash, bash, Batch-Files, Communications Development, Development, DNS, Internet protocol suite, Linux, Mac, Mac OS X / OS X / MacOS, Power User, Scripting, Software Development, TCP | Leave a Comment »
Posted by jpluimers on 2022/11/12
This is fine #Twitter (illustration inspired by KC Green; creation video below)
(Edit 20221114: script for high-res images; more tweets from Jan) (Edit 20221116: hat-tip to Sam) (Edit 20221120: archiving t.co links by Michele Weigle) (Edit 20221122: added article by Johan van der Knijff) (20221128 Tapue export tool by Mike Hucka)
Time to be prepared:
[Wayback/Archive] Elon Musk Warns Twitter Bankruptcy Possible as Senior Executives Exit – Bloomberg
The below will help you exporting your Twitter content (Tweets, DMs, media), perform some conversions on them and optionally delete (parts of) your content.
Important: keep your Twitter account afterwards (to prevent someone from creating a new account with the same handle).
Posted in *nix, *nix-tools, Awk, Development, Lightweight markup language, MarkDown, Mastodon, Power User, SocialMedia, Software Development, Twitter | Leave a Comment »
Posted by jpluimers on 2022/11/07
Some interesting bits from [WayBack] Stop using tail -f (mostly):
- say you want to watch the file
production.log:$ less +F production.log Important log information here Waiting for data... (interrupt to abort)Here you have pretty much the same behaviour you’d get with
tail.Now let’s say something interesting appears, and you want to search all the occurrences of “foo”. You can just hit
Ctrl-cto go to “normal”lessmode (as if you had opened the file without the+Fflag), and then you have all the normallessfeatures you’d expect, including the search with/foo. You can go to the next or previous occurrence withnorN, up and down withjandk, create marks withmand do all sort of things thatless(1)says you can do.Once you are done, just hit
Fto go back to watching mode again. It’s that easy.- When you need to watch multiple files at the same time,
tail -fcan actually give you a better output.
Related: [WayBack] shell – The ‘less’ command-line equivalent of ‘tail -f’ – Unix & Linux Stack Exchange
I prefer
tail -F-F – The -F option implies the -f option, but tail will also check to see if the file being followed has been renamed or rotated.
The
lessequivalent:less +F --follow-name
–jeroen
Posted in *nix, *nix-tools, less, Power User | Leave a Comment »
Posted by jpluimers on 2022/10/25
With the rise of *nix tools and infrastructure on Windows (including, but certainly not limited to Visual Studio Code and Windows Subsystem for Linux), I need to get acquainted to the new ways these interface to the Windows Console.
Since Windows Console is from the (now obsolete) UCS-2 days, so it is not even fully Unicode aware, and has trouble with UTF-8, UTF-16.
So here are some links for my reading list:
conhost.exe and condrv.sys, and the core everything is a file/object difference in the unix and Windows world)
- Keep the default value of ‘termwintype’ as “”.
- If ‘termwintype’ is “” and if ConPTY is considered stable (Win10 1903? or later), use ConPTY.
- If ‘termwintype’ is “” and if ConPTY is considered unstable (1809), use winpty.
- If ‘termwintype’ is “” and if ConPTY is not available (before 1809), use winpty.
- If ‘termwintype’ is “conpty”, use ConPTY even if it is unstable (1809).
- If ‘termwintype’ is “winpty”, use winpty.
conhost.exe)–jeroen
Posted in *nix, *nix-tools, CommandLine, ConPTY, Console (command prompt window), Development, Linux, Power User, Software Development, Windows, Windows 10, Windows 11, Windows Development, Windows Terminal, WSL Windows Subsystem for Linux | Leave a Comment »
Posted by jpluimers on 2022/09/20
If you ever want a good visual representation to compare the breaking distance for a car at two different speeds, and see at what speed you will hit the human “obstacle”, then use the Python script mkbremsweg.py.
Git repository: [Wayback/Archive.is] joschtl / bremsweg · GitLab.
The image is generated in the current directory
It probably won’t work on Windows as it dynamically builds a very long command-line calling ImageMagick tool [Wayback/Archive.is] convert once to do all the drawing.
The text in the picture for now is hardcoded in German, but would be easy to adopt.
The fonts used are and FreeSans and [Wayback/Archive.is] Alte DIN 1451 Mittelschrift Font Family · 1001 Fonts (which the Germans use for Traffic Signage and is very similar to fonts used in other countries).
Calculations are based on [Wayback/Archive.is] Bremsweg-Rechner für Anhalteweg & Bremsweg – Johannes Strommer.
Via:
–jeroen
Posted in *nix, *nix-tools, cars, Development, ImageMagick, LifeHacker, Power User, Python, Scripting, Software Development, Traffic, Windows | Leave a Comment »
Posted by jpluimers on 2022/08/26
Last winter, I discovered that the OpenVPN version on Chocolatey was really old: it had not been updated since 2019.
Most Chocolatey maintainers are volunteers and sometimes the burden can become too large. Back then the maintainer was [Wayback/Archive] Chocolatey Software | wget, but luckily [Wayback/Archive] Chocolatey Software | dgalbraith has stepped in and in March 2022 bumped the version from [Wayback/Archive] Chocolatey Software | OpenVPN 2.4.7 to [Wayback/Archive] Chocolatey Software | OpenVPN – Open Source SSL VPN Solution 2.5.4 and kept maintaining (currently there is [Wayback/Archive] Chocolatey Software | OpenVPN – Open Source SSL VPN Solution 2.5.7).
Posted in *nix, *nix-tools, Chocolatey, Hardware, Network-and-equipment, OpenVPN, Power User, ssh/sshd, VPN, Windows | Leave a Comment »
Posted by jpluimers on 2022/08/16
A while back Kristian Köhntopp (isotopp) wrote a blog post after quite a Twitter argument where he poses against using git empty commits. I’m with Kris: don’t use them for anything, especially not for kicking off your CI/CD.
Basically his blog post is all about avoiding to think you have a golden hammer, and avoid falling for the Law of the instrument – Wikipedia.
Originally, Abraham Maslow said in 1966:
“I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.”
For me this has all to do with preventing technical debt: find the right tool to kick your CI/CD pipeline after part of that chain somehow malfunctioned is way better than polluting the commit history with empty commits.
His blog post: [Wayback/Archive.is] Empty commits and other wrong tools for the job | Die wunderbare Welt von Isotopp
The most important bit in it:
And since we are talking about CI/CD pipelines: Don’t YAML them. Don’t JSON them. Don’t XML them.
…
Programming in any of these three is wrong use of tooling, and you should not do it.
- YAML, JSON and XML are for declarative things.
- Python, Go and Rust are for procedural things.
- Bash is for interactive use only.
Use the proper tooling for the job. Be an engineer.
This very much reminds me of an Entwickler Konferenz keynote a long time ago, where Neal Ford made the point that most software engineers act very much unlike what is expected from traditional engineering way of operating where the engineer is both responsible and liable for his actions.
The start of the Twitter thread: [Archive.is] Kristian Köhntopp on Twitter: “A lot of people right now that git is an API and triggering CI/CD pipelines with empty commits replaces the equivalent of a Kubernetes controller for their fragile pile of bash in git triggers. This is broken and begets more brokenness. Evidence:… “
The tweet that started the subtweet: [Archive.is] Florian Haas on Twitter: “(For anyone wondering, what’s nice about this one is it works in any CI. So you don’t have to remember how to manually kick off a GitLab CI pipeline or GitHub Action or Zuul job, you just push an empty commit and off you go.)”
Other relevant tweets:
This solution still has one drawback. Gitlab requires a project specific token. If every developer uses the same token, its validity is bound to the project and not the individual contributor. While Gitlab allows users to create personal access tokens, you cannot require such a token to trigger a pipeline.
Yes, you want to avoid shell too (anything like for instance sh, ash, dash, bash or zsh), but you have to know it (and understand why to avoid it) as often it is the only interactive way to access systems from the console.
And of course Kris also wrote a big document on that too, which is available as full PDF (Wayback), full HTML (Wayback) and chaptered HTML Die UNIX Shell /bin/sh.
But more importantly, Kris wrote [Wayback/Archive.is] Using Python to bash | Die wunderbare Welt von Isotopp which is about using Python to do things you might be tempted to do in the shell. It quotes
Shell is a thing you want to understand and then not use, because you learned to understand it.
which is from the German post in thread [Wayback/Archive.is] Bashprogrammierung, wo gehts am besten los which quotes Kris’ 1998 message:
From kris Tue Sep 1 11:26:12 1998 From: kris Newsgroups: de.comp.os.unix.misc Subject: Re: Shell-Frage, find, xargs, kopieren von vielen Dateien References: <6seh24$q9a$2...@nz12.rz.uni-karlsruhe.de> From: kr...@koehntopp.de (Kristian Koehntopp) Alignment: chaotic/neutral X-Copyright: (C) Copyright 1987-1998 Kristian Koehntopp -- All rights reserved. MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Marc.Hab...@gmx.de (Marc Haber) writes: >mir ist das ganze Zeug mit der Shell, find, xargs und Konsorten noch >reichlich verschlüsselt. http://www.koehntopp.de/kris/artikel/unix/shellprogrammierung/ >xargs hin oder sollte ich besser ein Perlskript schreiben? Verwende Perl. Shell will man koennen, dann aber nicht verwenden. Kristian
–jeroen
Posted in *nix, *nix-tools, ash/dash, ash/dash development, bash, bash, Conference Topics, Conferences, Continuous Integration, Development, DVCS - Distributed Version Control, Event, git, Power User, Scripting, sh, Sh Shell, Software Development, Source Code Management, Technical Debt | Leave a Comment »
The Wiert Corner - irregular stream of stuff 