The Wiert Corner – irregular stream of stuff

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

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Archive for the ‘*nix’ Category

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Cryptosense Discovery

Posted by jpluimers on 2022/03/15

This is cool: [Wayback] Cryptosense Discovery:

Free tool that discovers security configuration errors in SSH and TLS servers and explains how to fix them. Supports STARTTLS and can also scan HTTPS, POP3, IMAP and SMTP servers.

It gives you a list of servers a target domain uses (for purposes like web, email, etc) that can have external encryption enabled, then allows you to test these.

The list by default has only servers within that target domain enabled, but you can optionally include other servers (for instance if a domain uses a third party for their SMTP handling).

Basically it is the web-counterpart of a tool like testssl.sh (which I have written about before).

Found while checking out how to test the MX security of a domain using [Wayback] testssl.sh as I forgot the syntax, which in retrospect is dead easy as per [Wayback] tls – How to use testssl.sh on an SMTP server? – Information Security Stack Exchange (thanks [Wayback] Z.T.!):

…

testssl.sh --mx <domain name>

works fine.

testssl.sh -t smtp <ip>:25

and

testssl.sh -t smtp <ip>:587

also work fine.

Note that not specifying the port assumes port 443, despite specifying protocol smtp. That doesn’t work.

…

Also, you might try discovery.cryptosense.com which does the same thing only better

That website is made by the cool people at [Wayback] Cryptosense.

Both are a lot easier than the alternatives described in [Wayback] Blog · How to test SMTP servers using the command-line · Halon MTA: using nslookup and dig for determining the affected hosts, using nc or telnet for testing basic connectivity, using [Wayback/Archive.is] openssl s_client to test TLS, and [Wayback/Archive.is] smtpping for measuring throughput.

In addition to the above tools mentioned in the blog, I’ve also used sendEmail (note case sensitivity), ehlo-size, and swaks.

This is what I tested:

–jeroen

Posted in *nix, *nix-tools, Awk, bash, bash, Communications Development, Development, DNS, Encryption, grep, HTTPS/TLS security, Internet, Internet protocol suite, Power User, Scripting, Security, SMTP, Software Development, SSH, ssh/sshd, TCP, testssl.sh, TLS | Leave a Comment »

The Delphi documentation site docwiki.embarcadero.com has been down/up oscillating for 4 days is now down for almost a day.

Posted by jpluimers on 2022/03/08

The [Wayback/Archive] Embarcadero/IDERA Documentation Wiki has been mostly down since March 3rd, 2022 (not the main page, but almost all other pages are).

I modified [Wayback/Archive] Docwiki https – EmbarcaderoMonitoring to show the actual status of a deeper page as the (mostly static) top page is up, so monitoring that is useless as the deeper pages are down.

The deeper pages are dynamic and require a functioning MySQL database connection. That connection is mostly down (the error message is not clear, so this could be a network or a database server problem, or maybe even a loadbalancer gradually entering bit heaven).

Since it had been down for like 6 days in February*, I’d expect Idera to keep an eye on it and prepare for more downtime. Apparently that’s either not a 24×7 thing for them or  they missed the “pre” in preparation as it is dead-silent on .

It also runs on an unsupported version of Mediawiki 1.31** which by itself does not explain the outage, but does indicate that their idea of handling their internal lifetime management is different than what they advocate to clients in their software subscription model, see [Wayback/Archive] Delphi – Embarcadero store, [Wayback/Archive] Update Subscription – Embarcadero and [Wayback/Archive] Special Offers on RAD Studio, Delphi & C++Builder – Embarcadero:

Read the rest of this entry »

Posted in *nix, Bookmarklet, Delphi, Development, JavaScript/ECMAScript, Lightweight markup language, MediaWiki, Monitoring, Power User, Scripting, SocialMedia, Software Development, Twitter, Uptimerobot, Web Browsers | Leave a Comment »

Some insights on how readlink approached canonicalisation of a filename having symlinks

Posted by jpluimers on 2022/03/03

Cool, I didn’t realise how readlink operated, but found out a bit more in the answers to [Wayback] symlink – How to get full path of original file of a soft symbolic link? – Unix & Linux Stack Exchange, thanks to [Wayback] daisy, [Wayback] Peter.O and [Wayback] Gilles ‘SO- stop being evil’:

  • Try this line: 
    readlink -f `which command`

    If command is in your $PATH variable , otherwise you need to specify the path you know.

    -f will return a path to a non-existent final target, so long as the intermediate link targets exist… Use -e to avoid this, ie. -e will return null if the final target does not exist. – Peter.O

  • Under Linux, readlink reads the contents of a symlink, and readlink -f follows symlinks to symlinks to symlinks, etc., until it finds something that isn’t a symlink.

–jeroen

Posted in *nix, *nix-tools, ash/dash, bash, bash, Development, Power User, Scripting, Software Development | Leave a Comment »

Too bad: ESXi busybox has `diff`, but not `patch`

Posted by jpluimers on 2022/03/02

On my ESXi boxes, I have a directory with local scripts that in part depend on the machine.

So I contemplated patching the dending parts with patch.

Then I found out that the BusyBox that VMware built for ESXi does have diff, but not patch:

# $(readlink -f "`which diff`")
BusyBox v1.29.3 (2021-01-17 01:25:00 PST) multi-call binary.
BusyBox is copyrighted by many authors between 1998-2015.
Licensed under GPLv2. See source distribution for detailed
copyright notices.

Usage: busybox [function [arguments]...]
   or: busybox --list
   or: function [arguments]...

    BusyBox is a multi-call binary that combines many common Unix
    utilities into a single executable.  Most people will create a
    link to busybox for each function they wish to use and BusyBox
    will act like whatever it was invoked as.

Currently defined functions:
    addgroup, adduser, arch, ash, awk, basename, bunzip2, bzcat, bzip2, cat, chgrp, chmod, chown, chvt, cksum, clear, cp, crond,
    cut, date, dd, delgroup, deluser, diff, dirname, dnsdomainname, du, echo, egrep, eject, env, expr, false, fdisk, fgrep, find,
    fstrim, getty, grep, groups, gunzip, gzip, halt, head, hexdump, hostname, inetd, init, kill, ln, logger, login, ls, lzop,
    lzopcat, md5sum, mkdir, mkfifo, mknod, mktemp, more, mv, nohup, nslookup, od, passwd, poweroff, printf, readlink, reboot,
    reset, resize, rm, rmdir, sed, seq, setsid, sh, sha1sum, sha256sum, sha3sum, sha512sum, sleep, sort, ssl_client, stat, stty,
    sum, sync, tail, tar, taskset, tee, test, time, timeout, touch, true, uname, uniq, unlink, unlzop, unzip, usleep, vi, watch,
    wc, wget, which, who, xargs, zcat

This list is much shorter than the applets that are supported in [Wayback] BusyBox – The Swiss Army Knife of Embedded Linux, so VMware did cut out quite a few.

Generating the above output

The command-line trick above first expands diff using the output of which diff, then finds out where it links to through the readlink -f wrapper there the back-quotes “`” get this output:

# readlink -f "`which diff`"
/usr/lib/vmware/busybox/bin/busybox

Finally the $(...) executes the output of readlink.

It is based on [Wayback] bash – How to resolve symbolic links in a shell script – Stack Overflow

readlink -f "$path"

Editor’s note: The above works with GNU readlink and FreeBSD/PC-BSD/OpenBSD readlink, but not on OS X as of 10.11.GNU readlink offers additional, related options…

Need to devise a way to apply patches

Given there is no patch, I need to think about a good way to apply patches, for instance to snip this into /etc/rc.local.d/local.sh in a reliable way:

## BEGIN-PATCH-PATH

# local binaries are in /vmfs/volumes/NVMe980PRO_1TB/local-bin/
# link that directory from /opt/bin
# then add /opt/bin to the PATH in /etc/profile so that on each logon it becomes available
# this means you need to logon twice after reboot:
# - first to patch /etc/profile
# - second to have the correct PATH loaded from /etc/profile
# direcory exist trick from https://stackoverflow.com/questions/59838/how-can-i-check-if-a-directory-exists-in-a-bash-shell-script

patch_etc_profile_PATH() {
    if [ -d "$1" ]; then
      ln -s "$1" "/opt/bin"
      sed -i -e 's!PATH=/bin:/sbin!PATH=/bin:/sbin:/opt/bin/!' /etc/profile
    fi
}

patch_etc_profile_PATH /vmfs/volumes/NVMe980PRO_1TB/local-bin/

## END-PATCH-PATH

–jeroen

Posted in *nix, *nix-tools, ash/dash, ash/dash development, BusyBox, Development, ESXi6, ESXi6.5, ESXi6.7, ESXi7, Power User, Scripting, Software Development, Virtualization, VMware, VMware ESXi | Leave a Comment »

Bash functions to encode and decode the ‘Basic’ HTTP Authentication Scheme

Posted by jpluimers on 2022/02/24

IoT devices still often use the ‘Basic’ HTTP Authentication Scheme for authorisation, see [Wayback] RFC7617: The ‘Basic’ HTTP Authentication Scheme (RFC ) and [Wayback] RFC2617: HTTP Authentication: Basic and Digest Access Authentication (RFC ).

Often this authentication is used even over http instead of over https, for instance the Egardia/Woonveilig alarm devices I wrote about yesterday at  Egardia/Woonveilig: some notes about logging on a local gateway to see more detailed information on the security system. This is contrary to guidance in:

  • RFC7617:
       This scheme is not considered to be a secure method of user
   authentication unless used in conjunction with some external secure
   system such as TLS (Transport Layer Security, [RFC5246]), as the
   user-id and password are passed over the network as cleartext.
  • RFC2617:
       "HTTP/1.0", includes the specification for a Basic Access
   Authentication scheme. This scheme is not considered to be a secure
   method of user authentication (unless used in conjunction with some
   external secure system such as SSL [5]), as the user name and
   password are passed over the network as cleartext.

Fiddling with those alarm devices, I wrote these two little bash functions (with a few notes) that work both on MacOS and in Linux:

# `base64 --decode` is platform neutral (as MacOS uses `-D` and Linux uses `-d`)
# `$1` is the encoded username:password
function decode_http_Basic_Authorization(){
  echo $1 | base64 --decode
  echo
}

# `base64` without parameters encodes
# `echo -n` does not output a new-line
# `$1` is the username; `$2` is the password
function encode_http_Basic_Authorization(){
  echo $1:$2 | base64
}

The first decodes the <credentials> from a Authorization: Basic <credentials> header into a username:password clean text followed by a newline.

The second one encodes a pair of username and password parameters into such a <credentials> string.

They are based on these initial posts that were not cross platform or explanatory:

  1. [Wayback] Decode HTTP Basic Access Authentication – Stack Pointer
  2. [Wayback] Create Authorization Basic Header | MJ’s Web Log

–jeroen

Posted in *nix, *nix-tools, Apple, Authentication, bash, bash, Communications Development, Development, HTTP, Internet protocol suite, Linux, Mac OS X / OS X / MacOS, Power User, Scripting, Security, Software Development, TCP, Web Development | Leave a Comment »

Viewing the last lines of the postfix log with journalctl (with help from Unix & Linux Stack Exchange)

Posted by jpluimers on 2022/02/24

Two command-lines I use to view my Postfix logs:

  1. journalctl --unit postfix --since "2 days ago"
  2. journalctl --unit postfix --pager-end

Note that neither of these work well with the --follow (or equivalent -f) option, as this will effectively disable the pager (which by default is less).

The second is via [Wayback] systemd – How to see the latest x lines from systemctl service log – Unix & Linux Stack Exchange (which got the--pagerend bit wrong, as it misses a dash and should be --pager-end, but still thanks [Wayback] Daniel Kmak):

Just:

journalctl -u SERVICE_NAME -e

Parameter -e stands for:

-e –pagerend

…

That’s the one ! Other answers will go through the whole log to get to its end, which can be veeeeery long for large syslogs.

The last bit (by [Wayback] Léo Germond, thanks!) is why I like it most.

Similarly, specifying --since in the first example will not go through the whole log.

Some background information:

Read the rest of this entry »

Posted in *nix, *nix-tools, bash, Development, journalctl and journald, Linux, postfix, Power User, Scripting, Software Development, systemd | Leave a Comment »

Sendmail queue files: “Mhost map: lookup” deferred

Posted by jpluimers on 2022/02/22

I had forgotten about sendmail mail queue entries that start with Mhost map: lookup.

It it happens for all email then you have a DNS problem.

When it happens only for a few emails, then usually that domain is gone (often because of SPAM reasons).

via: [Wayback] “Mhost map: lookup” – Google Search

–jeroen

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

I always forget how simple it is to show the definition of bash function or alias (via: Stack Overflow)

Posted by jpluimers on 2022/02/17

I always facepalm myself after looking up this: [Wayback] Can bash show a function’s definition? – Stack Overflow (thanks [Wayback] Benjamin Bannier!):

…

Use type. If foobar is e.g. defined in your ~/.profile:

$ type foobar
foobar is a function
foobar {
    echo "I'm foobar"
}

…

type will also expand aliases, which is a nice bonus :) – [Wayback] Esdras Lopez

–jeroen

Posted in *nix, *nix-tools, bash, bash, Development, Power User, Scripting, Software Development | Leave a Comment »

Creating a bootable USB installer for ESXi on other operating systems than Windows

Posted by jpluimers on 2022/02/17

I wrote about Creating a bootable USB installer for ESXi and use it to create a bootable ESXi installation.

Just in case I ever need to do this on a non-Windows system, some links:

–jeroen

Posted in *nix, Apple, ESXi6, ESXi6.5, ESXi6.7, ESXi7, Linux, Mac OS X / OS X / MacOS, Power User, Virtualization, VMware, VMware ESXi, Windows | Leave a Comment »

When high SEO ranking fails to give you a reliable result: IsItDownRightNow.com failed to detect the WayBack Machine outage

Posted by jpluimers on 2022/02/11

A high SEO ranking does not automatically indicate a reliable result.

When the WayBack Machine was down a while ago (it responded to traceroute UDP requests, but would not establish TCP connections on ports 80 and 443), the first Google hit for detecting down status (searching for [Archive.is] waybackmachine down – Google Search) failed miserably because it redirected web.archive.org (which fails) to http://www.archive.org (which succeeds):

IsIdDownRightNow failing to detect web.archive.org downtime

IsIdDownRightNow failing to detect web.archive.org downtime

Luckily when asking around on Twitter:

  • others were experiencing the same problem, not just in The Netherlands, but also in other countries
  • after trying a few things, the WayBack machine got backup [Archive.is] before I could try cURL.
  • I got pointed at www.uptrends.com/tools/uptime which correctly does check the right subdomain and shows it is down from many locations:

Read the rest of this entry »

Posted in *nix, cURL, Infrastructure, Internet, InternetArchive, LifeHacker, Power User, WayBack machine | Leave a Comment »

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