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

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Archive for the ‘*nix’ Category

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Postfix for relaying SMTP, some info about my own configuration

Posted by jpluimers on 2020/03/20

I’ve a bunch of secondary MX servers using postfix (which I like a lot over sendmail). Basically all their configurations are very similar:

  1. To the file /etc/postfix/relay, add a list of domains to relay for, each ending with a space followed by OK as per
    [WayBack] Configure Postfix to relay mail to multiple internal mail servers w/different domains
  2. Run postmap /etc/postfix/relay to update the relay database file.
  3. Ensure that /etc/postfix/main.cf has these settings (note that the FQDN – in the example smtp3.example.org – isn’t always returned by hostname --fqdn, see below):
    1. inet_interfaces = all
    2. myhostname = smtp3.example.org
    3. smtpd_helo_required = yes
    4. smtpd_helo_restrictions = permit_mynetworks, reject_invalid_helo_hostname, reject_non_fqdn_helo_hostname, reject_unknown_helo_hostname
  4. rcpostfix restart && rcpostfix status

Check the functionality with journalctl -u postfix.

FQDN – how to get myhostname

This usually gives a good indication of your external FQDN, but depending on your network circumstances it might not at all be the FQDN of your machine:

dig +noall +answer +short -x `curl -s ipv4.whatismyip.akamai.com` | sed 's/\.$//'

I got there through these StackExchange answers:

Testing with sendEmail

Then test with sendEmail from [WayBack] GitHub – mogaal/sendemail: lightweight, command line SMTP email client, with statements like these

The most recent version is now at [Wayback/Archive.is] GitHub – zehm/sendEmail: SendEmail is a lightweight, command line SMTP email client.

  • sendEmail -o fqdn=sending.example.org -f sender@example.org -t recipient@example.com -u message-subjetc -s smtp3.example.org -m message-text
  • sendEmail -o fqdn=sending.example.org -f sender@example.org -t recipient@example.com -u message-subjetc -s smtp3.example.org -m message-text -v -v -v -v

If you get an error containing 450 4.7.1 … Helo command rejected: Host not found, then reject_unknown_helo_hostname works, but your -o fqdn= parameter contains an invalid hostname.

More sending examples are in the sendEmail documentation.

If you want to know more about fighting SPAM, then continue at [WayBack] Fighting Spam – What can I do as an: Email Administrator, Domain Owner, or User? – Server Fault

–jeroen

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

bash – How to add a progress bar to a shell script? – Stack Overflow

Posted by jpluimers on 2020/03/17

From [WayBack] bash – How to add a progress bar to a shell script? – Stack Overflow (thanks Mitch Haile!):

You can implement this by overwriting a line. Use \r to go back to the beginning of the line without writing \n to the terminal.

Write \n when you’re done to advance the line.

Use echo -ne to:

  1. not print \n and
  2. to recognize escape sequences like \r.

Here’s a demo:

echo -ne '#####                     (33%)\r'
sleep 1
echo -ne '#############             (66%)\r'
sleep 1
echo -ne '#######################   (100%)\r'
echo -ne '\n'

–jeroen

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

Mounting a Time Machine backup under Linux so you can send it to Backblaze using Restic…

Posted by jpluimers on 2020/03/16

[WayBack1/WayBack2] Memo to self: Ich will ein Time Machine Backup unter Linux mounten, um das “Latest” Verzeichnis mit Restic an Backblaze senden zu können. Schritt 1: Sp… – Kristian Köhntopp – Google+:

Memo to self: Ich will ein Time Machine Backup unter Linux mounten, um das “Latest” Verzeichnis mit Restic an Backblaze senden zu können.

Schritt 1: Sparsebundle mounten

# ls -l /export/tm_kk/
total 8
drwx—— 3 kris users 4096 Oct 21 16:24 KK.sparsebundle

Geht mit

# git clone git://github.com/torarnv/sparsebundlefs.git
# cd sparsebundlefs; make
# mkdir -p /bundles/tm_kk
# sparsebundlefs /export/tm_kk/KK.sparsebundle /bundles/tm_kk
# ls -lh /bundles/tm_kk
total 0
-r——– 1 root nogroup 1.5T Oct 21 16:24 sparsebundle.dmg

Schritt 2: DMG loopmounten

# fdisk -l /bundles/tm_kk/sparsebundle.dmg
Disk /bundles/tm_kk/sparsebundle.dmg: 1.5 TiB, 1648462135296 bytes, 3219652608 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 15FCCBBD-49E4-42BB-B359-EF662F9916CF

Device Start End Sectors Size Type
/bundles/tm_kk/sparsebundle.dmg1 40 409639 409600 200M EFI System
/bundles/tm_kk/sparsebundle.dmg2 409640 3219390423 3218980784 1.5T Apple HFS/HFS+

# kpartx -a -v /bundles/tm_kk/sparsebundle.dmg
add map loop8p1 (253:1): 0 409600 linear 7:8 40
add map loop8p2 (253:19): 0 3218980784 linear 7:8 409640

# mkdir -p /hfs/tm_kk
# mount -o ro -t hfsplus /dev/mapper/loop8p2 /hfs/tm_kk
# b=$(readlink /hfs/tm_kk/Backups.backupdb/KK/Latest)
# ls -l /hfs/tm_kk/Backups.backupdb/KK/$b
total 0
drwxr-xr-x 1 root root 30 Oct 21 14:26 ‘Macintosh HD’

Schritt 3: tmfs mount

Ein Time Machine Backup enthält doofe Hardlinks auf Verzeichnisse. Das kann Linux so nicht, und man muß das noch einmal mit tmfs fusemounten. Seufz.

# apt-get install tmfs
# mkdir -p /tmfs/tm_kk
# tmfs /hfs/tm_kk /tmfs/tm_kk
# ls -l /tmfs/tm_kk/KK/Latest/
total 0
drwxr-xr-x 1 root root 30 Oct 21 14:26 ‘Macintosh HD’

Das durchzulesen ist nicht mal langsam.

Schritt 4: Abbauen

# umount /tmfs/tm_kk
# umount /hfs/tm_kk/
# kpartx -d -v /bundles/tm_kk/sparsebundle.dmg
del devmap : loop8p1
del devmap : loop8p2
loop deleted : /dev/loop8
# umount /bundles/tm_kk

Schritt 5: Den Mist scripten

…

A few important comments from the WayBack2 link:

Jeroen Wiert Pluimers:

So your time machine data is on a Linux disk that you export from Linux to MacOS? (as otherwise, I don’t understand what /export/tm_kk/KK.sparsebundle is for)

Kristian Köhntopp:

Yes, I am running netatalk, SMB and NFS on an Ubuntu 18.04.

Jeroen Wiert Pluimers:

+Kristian Köhntopp Thanks. What do you envision as steps to restore a complete time machine?

Kristian Köhntopp:

We will see. I do not see that as normally necessary. Mostly I do not want to lose the work on my laptop, and am just to lazy to restrict the backup to that. In general, it should be possible to create this as a writeable setup so that I get the data back. I will probably never recreate a full runnable mac setup from this emergency offsite backup.

Tools used:

–jeroen

Posted in *nix, *nix-tools, Apple, Backup, Mac, Mac OS X / OS X / MacOS, MacBook, Power User | Leave a Comment »

Linux – How to Securely Copy Files Using SCP examples

Posted by jpluimers on 2020/03/16

I love short and to the point examples. The list of permutations for scp is at [WayBack] Linux – How to Securely Copy Files Using SCP examples.

–jeroen

Read the rest of this entry »

Posted in *nix, *nix-tools, Development, Internet protocol suite, Power User, SSH, TCP | Leave a Comment »

Some links on bind rndc

Posted by jpluimers on 2020/03/13

No, this is not a random number generator, according to the documentation, bind rndc is the name server control utility. Again very undescriptive; luckily the full name found elsewhere is Remote Name Daemon Control.

Some links for my archive as often there are no man-pages installed on systems with bind:

–jeroen

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

Show the mmc and USB disks on a Raspberry Pi

Posted by jpluimers on 2020/03/13

Small trick:

find /dev | grep "sd\|mmc" && ls -al /dev/disk/by-id/

–jeroen

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

command line – Recursive tar compression? – Ask Ubuntu

Posted by jpluimers on 2020/03/09

Since I always forget one-letter command-line options: [WayBack]command line – Recursive tar compression? – Ask Ubuntu (thanks andrew.46 for this very nice answer!):

Try:

tar -czvf directorios.tar.gz folder

A few notes:

  1. Recursion is the default, from the tar man pages: 
    -c, --create
    Create a new archive.  Arguments supply the names of the files to be archived.
    Directories  are  archived  recursively,  unless  the --no-recursion option is
    given.

    Although this can be turned off by using the --no-recursion option…

  2. You need the archive name immediately after the -f option, the correct sequence being: 
    tar -c [-f ARCHIVE] [OPTIONS] [FILE...]
         ^^^^^^^^^^
  3. For a more flexible command line (particularly if you wanted to use other compression utilities apart from gzip with tar) you could omit the -z option and use -a option to allow tar to automatically decide which compressor to use based on the archive suffix: 
    -a, --auto-compress
    Use archive suffix to determine the compression program.

    Recognised suffixes are:

    • .gz : gzip
    • .tgz : gzip
    • .taz : gzip
    • .Z : compress
    • .taZ : compress
    • .bz2 : bzip2
    • .tz2 : bzip2
    • .tbz2 : bzip2
    • .tbz : bzip2
    • .lz : lzip
    • .lzma : lzma
    • .tlz : lzma
    • .lzo : lzop
    • .xz : xz

tar is pretty cool :)

–jeroen

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

GitHub – facebook/osquery: SQL powered operating system instrumentation, monitoring, and analytics.

Posted by jpluimers on 2020/03/09

Boy, I wish I had found this years ago: [WayBack] GitHub – facebook/osquery: SQL powered operating system instrumentation, monitoring, and analytics.

No more remembering all those nifty configuration and log file details by heart, just install and query using SQL.

Now you need to learn a “database” schema, however that’s the same for all supported operating systems.

Example installation steps:

  • brew install osquery
  • Get the official downloads for your OS from the osquery.io site.

Run interactively through osqueryi, then perform .help or .schema to get an impression of what is possible.

There is lots of documentation at [WayBack] osquery.

–jeroen

Posted in *nix, *nix-tools, Apple, Mac, Mac OS X / OS X / MacOS, Power User | Leave a Comment »

🔎Julia Evans🔍 on Twitter: “the ip command… “

Posted by jpluimers on 2020/03/06

[Archive.is] 🔎Julia Evans🔍 on Twitter: “the ip command… “

Larger image below the fold; thanks Julia!

Shortened transcript:

  • ip
    • lets you view and change network configuration
    • ip OBJECT COMMAND
    • object: addr, link, neigh, etc
    • command: add, show, delete, etc
  • ip addr list
    • shows IP addresses
  • ip route list
    • displays the route table
    • ip route list table all
  • ip netsh
    • manage network namespaces
  • ip link
    • network devices (like eth0)
  • ip neigh
    • view/edit the ARP table
  • ip xfrm
  • ip -s link
    • s is for statistics
    • shows transmitted/received packets for each device

Lots of additions in the Twitter Thread too, including (and some of them I still need to figure out):

Read the rest of this entry »

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

In Unix, what are some common dot files?

Posted by jpluimers on 2020/03/06

I came across some 20 year old Unix stuff a while ago, so I needed an historic reference of filenames starting with a dot (like .newsrc).

This is a pretty good one: [WayBack] In Unix, what are some common dot files?

–jeroen

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

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