Linux   Linux – rsyslog: parsing and splitting message fields



Until now I hadn’t used the options and features rsyslog comes with. Let me show a simple example I have done today. This is an example log line rsyslog has received from iptables (I have configured iptables to log certain connections attempts to identify and save devices with malware):

Sep 29 15:30:39 myserver kernel: [malware3] IN=ens192 OUT=ens192 MAC=XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX SRC=10.15.13.17 
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Linux   Linux – Simple DNS server using DNSmasq



This article offers a 5 min howto about configuring your own DNS server (perhaps for your company or maybe for your home network) using DNSmasq. Obviously, only the surface is covered on this post.

Given my router does not allow me to add host entries for local DNS resolution, I decided to use DNSMasq on one of my internal network … Read more

Icinga icon   Icinga – Notification template with notes support



I have just configured an Icinga2 notification template for hosts and services to replace the ugly and impractical default one.

Features

Not big things but useful in my opinion

Clear and nicely formatted layout

State based colors

State based icons

UTF Icons are included depending on the state of the host or service

Notes support

This notifications scripts can include … Read more

Icinga icon   Icinga – Notes section in markdown language



Not sure since what version this feature is available but I have started to use the notes section of the services i am monitoring in Icinga in markdown syntax.

icingaweb2 package version 2.6 that is compiled for Debian 10 (Buster).

Package: icingaweb2
Version: 2.6.2-3

You may think you do not need it for, but in my humble opinion it is … Read more

Linux   Linux – SQL Server command line to perform queries (mssql-cli)



There are different methods to run queries against an SQL Server from a Linux machine. The one I am using is mssql-cli (https://github.com/dbcli/mssql-cli)

As you can check in the related github website, it has the following features:

  • Auto-completion
  • Syntax highlighting
  • Query history
  • Configuration file support
  • Multi-line queries

Installation

The -Q parameter

It has been packetized for a lot of distributions … Read more

Linux   Linux – Show git branch in bash prompt



If you are a Git user, you can find very useful this custom prompt.

Branch

Shows working branch when it detects the current folder is a git one:

user1@labdebian ~/data $
user1@labdebian ~/data $ cd ../myproject/
user1@labdebian ~/myproject (master) $
user1@labdebian ~/myproject (master) $ git checkout -b branch1
Switched to a new branch 'branch1'
user1@labdebian ~/myproject (branch1) $
user1@labdebian ~/myproject
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   Nextcloud – Error modifying files or folders: locked error



Yesterday I came across a problem in which I tried to modify (rename, delete, …) a folder and it returned an error.

Nextcloud logs (/var/www/nextcloud/data/nextcloud.log) showed the following:

"reqId":"Pf4KW9q1WDVe1YdmG0Mt","level":3,"time":"2019-09-10T16:36:53+00:00","remoteAddr":"63.223.129.127","user":"user1","app":"no app in context","method":"DELETE","url":"\/remote.php\/dav\/files\/user1\/ALBUMS\/New%20folder","message":{"Exception":"OCP\\Lock\\LockedException","Message":"\"files\/8010dab5adf49336ecdaf75a2008d5ab\" is locked","Code":0,"Trace":[{"file":"\/var\/www\/html\/nextcloud\/lib\/private\/Files\/Storage\/Common.php","line":779,"function":"changeLock","class":"OC\\Lock\\DBLockingProvider","type":"->","args":["files\/8010dab5adf49336ecdaf75a2008d5ab",2]},{"file":"\/var\/www\/html\/nextcloud\/lib\/private\/Files\/Storage\/Wrapper\/Wrapper.php","line":615,"function":"changeLock","class":"OC\\Files\\Storage\\Common","type":"->","args":["Nueva carpeta",2,{"__class__":"OC\\Lock\\DBLockingProvider"}

Solution

Enter maintenance mode

sudo -u www-data php occ maintenance:mode --on

Then, all entries of the table oc_file_locks … Read more

Security   Security – List available cipher suite using nmap



If you are in process of securing your web server or site, there are some tools and online resources that can help us a lot (in one of the following posts will show you some of them).

But simply using the command the fantastic nmap tool, another interesting feature is listing the available cipher suite certain site offers using the … Read more

Security   Security – View HTTP headers using tcpdump



If you need to trace the HTTP request and response headers by capturing the related packets, you can use tcpdump in this way:

 tcpdump -i ens192 -A -s 10240 'tcp port 80' | grep -v IP | egrep --line-buffered "..(GET |\.HTTP\/|POST |HEAD )|^[A-Za-z0-9-]+: " |sed -r 's/..(GET |HTTP\/|POST |HEAD )/\n\n\1/g'

For example, filtering tcp port 80 and 192.168.10.100 IP address:… Read more

Home Server icon   Home Server (7) – Install Linux Debian virtual machine in ESX



In this 7th post of the Home Server series, after having configured a SSD drive, a working ESX environment and the RAID disks, let’s create our first virtual machine based on Debian Linux.

For the goal we want to achieve (hosting a web server, our personal files, personal streaming server, …) we do not even need the graphic … Read more