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 ‘Linux’ Category

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domain name system – How to test DNS glue record? – Server Fault

Posted by jpluimers on 2016/05/26

Thanks Adrian W for providing the below example in your answer about obtaining GLUE record information for a domain.

It is an excellent showcase for the $IFS Internal Field Separator available in any nx shell.

In this case it is used to get the TLD (top-level domain) from the domain name specified at the command-line.

After that, it obtains the name servers for that TLD, and queries the glue records there, both using dig.

Here is a little shell script which implements Alnitak’s answer:

#!/bin/sh
S=${IFS}
IFS=.
for P in $1; do
  TLD=${P}
done
IFS=${S}

echo "TLD: ${TLD}"
DNSLIST=$(dig +short ${TLD}. NS)
for DNS in ${DNSLIST}; do
  echo "Checking ${DNS}"
  dig +norec +nocomments +noquestion +nostats +nocmd @${DNS} $1 NS
done

Pass the name of the domain as parameter:

./checkgluerecords.sh example.org

–jeroen

via domain name system – How to test DNS glue record? – Server Fault.

Posted in *nix, Apple, bash, Development, DNS, Linux, Mac, Mac OS X / OS X / MacOS, Mac OS X 10.4 Tiger, Mac OS X 10.5 Leopard, Mac OS X 10.6 Snow Leopard, Mac OS X 10.7 Lion, openSuSE, OS X 10.10 Yosemite, OS X 10.8 Mountain Lion, OS X 10.9 Mavericks, Power User, Scripting, Software Development, SuSE Linux | Leave a Comment »

Nice diskinfo alias showing du, df, btrfs, parted, lsblk

Posted by jpluimers on 2016/05/20

I bumped into a disk full issue again because of the btrfs/snapper combination in openSuSE and df basically lying about the disk space, so I w rote this Nice diskinfo alias showing du, df, btrfs, parted, lsblk.

You can combine this with A bash script to btrfs snapshot details like disk sizes (requires btrfs quota to be enabled) to find out which snapper snapshots take up a truckload of space and might be safely removed.

–jeroen

via: How can a partition be full if du does not show it is? (via: linux – Super User) #OpenSuSE #btrfs #snapshots « The Wiert Corner – irregular stream of stuff.

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

Latest Tumbleweed distribution update likely kills sshd

Posted by jpluimers on 2016/05/03

After a recent big update to OpenSuSE Tumbleweed, I could not ssh into my system any more.

Symptoms

The ssh client side would report a Read from socket failed: Connection reset by peer which I misinterpreted as the sshd not running at all.

Luckily the server is a VM, so I could reach the console. There I saw this:

sshd trying to load files it shouldn't

sshd trying to load files it shouldn’t

The files should not be loaded as they are not specified in the sshd_config file:

dsa and ecdsa not specified in the config file

dsa and ecdsa not specified in the config file

So I knew something was broken. After reading some messages in the forums.opensuse.org I got at Bug 977812 – sshd killed by SIGSYS on client connection

The cause

As usual with such issues the cause seems a combination of factors:

And we have the culprit, I believe: together with the glibc upgrade, openssl
was updated from 1.0.2g-1.1 to 1.0.2-2.12 which brought, among others, patch
openssl-urandom-reseeding.patch.

Temporary fix

A temporary fix is to comment out a line in /etc/sshd_config so you get this diff:

-UsePrivilegeSeparation sandbox # Default for new installations.
+# UsePrivilegeSeparation sandbox # Default for new installations.

Be sure to undo this as soon as you’ve received a final fix.

Final fix

A final fix is being fast-tracked so it appears in Tumbleweed soon.

I will report after deployment of [opensuse-factory] New Tumbleweed snapshot 20160502 released! as I think it contains the fix.

Aftermath

I already knew about openQA: Test summary which lists the builds, but not the changes in the builds.

Reading through Information Board or the like for Tumbleweed I found the openSUSE Mailinglist Archive: opensuse-factory which does the announcements and release notes for Tumbleweed.

It had both the announcement of the “big patch”, ssh bug report and temporary fix:

–jeroen

 

 

Posted in *nix, Communications Development, Development, Internet protocol suite, Linux, openSuSE, Power User, SSH, SuSE Linux, TCP, Tumbleweed | 2 Comments »

DVCS for your Linux etc configuration

Posted by jpluimers on 2016/04/11

Manually you can do it like this: How To Use Git to Manage your User Configuration Files on a Linux VPS | DigitalOcean.

But there is also etckeeper. There is even a set of manual installation steps for opensuse: backup – etckeeper for opensuse – bash script install and configure – Unix & Linux Stack Exchange.

Three important etckeeper gotchas with powerful scripts like pre-commit /etc/etckeeper/pre-commit.d:

  • Ensure you give them executable permissions like chmod 755.
  • Ensure they are valid sh scripts.
  • Do not give them the .sh extension:
    • fails: /etc/etckeeper/pre-commit.d/10rsync-var-lib-named-master
    • works: /etc/etckeeper/pre-commit.d/10rsync-var-lib-named-master.sh

–jeroen

via:

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

Upgrading from OpenSuSE 13.1 to 13.2

Posted by jpluimers on 2016/03/14

As etckeeper wasn’t available in the “normal” OpeenSuSE 13.1 package, I used the steps below to upgrade to 13.2 after reading SDB:System upgrade – openSUSE and How To Upgrade To openSUSE 13.2 From openSUSE 13.1 | Unixmen.

Note I installed inside tmux (to prevent any ssh disconnects from screwing the upgrade process):

Read the rest of this entry »

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

Getting the ESXi version from the console

Posted by jpluimers on 2016/03/10

Since ESXi is based on busybox, it is using ash a variation of sh (the classic bourne shell) called Almquist shell and most nxes use some form of bash a lot of things won’t work.

For instance, doesn’t support sh –version.

Luckily there are uname -mrs and (more elaborate) vmware -vl to get the version.

Note there is support busybox aliases so alias dir=”ls -laF” works, and you can define aliases for the version information too.

–jeroen

via:

Posted in *nix, *nix-tools, bash, Linux, Power User, SuSE Linux, Virtualization, VMware, VMware ESXi | Leave a Comment »

Mosh: the mobile shell

Posted by jpluimers on 2016/03/07

Reminder: install mosh and get it working when it runs behind a firewall.

Mobile shell that supports roaming and intelligent local echo. Like SSH secure shell, but allows mobility and more responsive and robust.

Links:

Then see how well it stacks up against or complements with the ssh/tmux combo.

–jeroen

Read the rest of this entry »

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

some more lsof, netstat and rpcinfo examples

Posted by jpluimers on 2016/03/07

Last friday I updated the examples at *nix networking – lsof: How to tell what process has a specific port open on Linux (via: Server Fault) as I needed to document some of the machines around here (so it becomes easier replacing them).

I also added some links to background information and (when I get to using it: OS X still goes without) a good iproute2 starter page.

–jeroen

Posted in *nix, *nix-tools, Apple, Communications Development, Cygwin, Development, Internet protocol suite, Linux, Mac, Mac OS X / OS X / MacOS, Mac OS X 10.6 Snow Leopard, MacBook, MacBook Retina, MacBook-Air, MacBook-Pro, MacMini, OS X 10.10 Yosemite, OS X 10.8 Mountain Lion, OS X 10.9 Mavericks, Power User, TCP | Leave a Comment »

Replace Boxee by Raspberry Pi as most TV support doing video+USB keybard over HDMI

Posted by jpluimers on 2016/02/22

If for instance your Boxee gets old or breaks down, you can use a Raspberry Pi as a replacement with Kodi as media player.

This combination will understand the Video+USB over HDMI which most TV supports officially named HDMI-CEC , but most vendors “invented” their own names (see list below).

The core is the kodi support for CEC.

Basically it comes down to using three cables going to the Pi: Power from TV (or some other source), HDMI to TV, and wired Ethernet. And a distribution for RaspberryPi containing kodi will work, for instance from OpenELEC Mediacenter – Download: Raspberry Pi Builds

Chad MILLER has more details on how to get this to work: My Boxee box is getting old, but I knew of no replacements. The problem is I …

Names known for HDMI-CEC via Wikipedia:

Anynet+ (Samsung), Aquos Link (Sharp), BRAVIA Link and BRAVIA Sync (Sony), HDMI-CEC (Hitachi), E-link (AOC), Kuro Link (Pioneer), INlink (Insignia), CE-Link and Regza Link (Toshiba), RIHD (Remote Interactive over HDMI) (Onkyo), RuncoLink (Runco International), SimpLink (LG), T-Link (ITT), HDAVI Control, EZ-Sync, VIERA Link (Panasonic), EasyLink (Philips), and NetCommand for HDMI (Mitsubishi).

Because of the naming, turning on CEC can be confusing: How to Enable HDMI-CEC on Your TV, and Why You Should

–jeroen

Posted in *nix, *nix-tools, Development, Hardware Development, Hardware Interfacing, HDMI, Linux, Power User, Raspberry Pi | Leave a Comment »

really cool playback tool for showing step by step stuff in terminals. …

Posted by jpluimers on 2016/02/05

Interesting:

Simon Wicki originally shared: really cool playback tool for showing step by step stuff in terminals. http://showterm.io

–jeroen

via: really cool playback tool for showing step by step stuff in terminals. ….

showterm

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

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