snap – snapcraft.io

Package any app for every Linux desktop, server, cloud or device, and deliver updates directly. Snap packages are a great way of running apps in an isolated state without using VMs or Containerisation. The website http://snapcraft.io has more details and examples such as this to get going:

A snap is a fancy zip file containing an application together with its dependencies, and a description of how it should safely be run on your system, especially the different ways it should talk to other software. Most importantly snaps are designed to be secure, sandboxed, containerised applications isolated from the underlying system and from other applications. Snaps allow the safe installation of apps from any vendor on mission critical devices and desktops.

Try this (you may need to install snapd)

 $ sudo snap install hello-world 

Now you have installed a snap. You can take a look inside the snap very easily, it shows up as a new directory on your system:

$ cd /snap/hello-world/current/

$ tree
.
├── bin ← this directory structure is just for convenience
│ ├── echo there is no hardcoded structure requirement other
│ ├── env than meta/snap.yaml
│ ├── evil
│ ├── sh
│ ├── showdev
│ └── usehw
└── meta ← your snap must have this directory
├── icon.png ← no prizes for guessing what this is
└── snap.yaml ← this is the required metadata

 

LXD Update Script

Simple shell script wrapper to update all lxd container hypervisor images running Debian or Ubuntu Linux. Run the below script on the host of your lxd server to update all the lxd containers running Ubuntu or Debian. Could be modified to suit CentOS/RedHat OS and/or you container OS of choice.

Script:

#!/bin/bash
# A simple shell script to update all lxd container hypervisor
# URL: https://bash.cyberciti.biz/virtualization/shell-script-to-update-all-lxd-container-hypervisor/
# Tested on : Ubuntu 16.04 LTS lxd server
# Tested on : Ubuntu/Debian lxd container hypervisor only
# ----------------------------------------------------------------------------
# Author: nixCraft
# Copyright: 2016 nixCraft under GNU GPL v2.0+
# ----------------------------------------------------------------------------
# Last updated 14 Aug 2016
# ----------------------------------------------------------------------------
# Set full path to bins
_apt="/usr/bin/apt-get"
_lxc="/usr/bin/lxc"
_awk="/usr/bin/awk"
# Get containers list
clist="$(${_lxc} list -c ns | ${_awk} '!/NAME/{ if ( $4 == "RUNNING" ) print $2}')"
# Use bash for loop and update all container hypervisor powered by Debian or Ubuntu
# NOTE: for CentOS use yum command instead of apt-get
for c in $clist
do
echo "Updating Debian/Ubuntu container hypervisor \"$c\"..."
${_lxc} exec $c ${_apt} -- -qq update
${_lxc} exec $c ${_apt} -- -qq -y upgrade
${_lxc} exec $c ${_apt} -- -qq -y clean
${_lxc} exec $c ${_apt} -- -qq -y autoclean
done

Reference:
https://bash.cyberciti.biz/virtualization/shell-script-to-update-all-lxd-container-hypervisor/

 

The detox utility

The detox utility renames files to make them easier to work with. It removes spaces and other such annoyances. It’ll also translate or cleanup Latin-1 (ISO 8859-1) characters encoded in 8-bit ASCII, Unicode characters encoded in UTF-8, and CGI escaped characters.

Sequences:
detox is driven by a configurable series of filters, called a sequence. Sequences are covered in more detail in detoxrc(5) and are discoverable with the -L option. Some examples of default sequences are iso8859_1 and utf_8.

Options:

The main options:

-f configfile
Use configfile instead of the default configuration files for loading translation sequences. No other config file will be parsed.
-h –help
Display helpful information.

-L’ List the currently available sequences. When paired with -v this option shows what filters are used in each sequence and any properties applied to the filters.

-n –dry-run
Doesn’t actually change anything. This implies the -v option.

-r’ Recurse into subdirectories.

-s sequence
Use sequence instead of default.

–special
Works on special files (including links). Normally detox ignores these files.

-v’ Be verbose about which files are being renamed.

-V’ Show the current version of detox.

Reference:
http://detox.sourceforge.net/

 

Find any E-Mail Address or Proxy Address In Active Directory

Who has this e-mail address? The address could be one of many different types of objects. A user mailbox, shared mailbox, distribution list, public folder, contact or resource could all contain that specific e-mail address. The problem with the Exchange Management Console in Exchange 2010 does not allow you to find any e-mail address only the primary.

Exchange Commandlets:

1: The following Exchange commandlet is the easiest method to find a specific e-mail address
or portion of an e-mail address. This will find any object within Exchange that has an exact
match to the e-mail address you place in the filter with -eq or email portion when using -like.

Get-Recipient [email protected]

Get-Recipient -Filter {EmailAddresses -like "*emailportion*"}

2: The following examples highlight the individual commandlets that target and return the
specific Exchange object types. You can substitute -eq with -like to include wild cards.

Get-Mailbox -Filter {EmailAddresses -eq "[email protected]" -or WindowsEmailAddress -eq "[email protected]"}

Get-MailboxContact -Filter {EmailAddresses -eq "[email protected]" -or WindowsEmailAddress -eq "[email protected]"}

Get-DistributionGroup -Filter {EmailAddresses -eq "[email protected]" -or WindowsEmailAddress -eq "[email protected]"}

Get-MailUser -Filter {EmailAddresses -eq "[email protected]" -or WindowsEmailAddress -eq "[email protected]"}

Reference:
http://powershellblogger.com/2015/10/find-any-e-mail-address-or-proxy-address-in-active-directory/

 

LSOF Utility and Commands

The lsof command is very handy and all Linux/Unix sysadmins should know abouyt it and make more use of it, here are some further details and examples.

(From Wikipedia) – lsof is a command meaning “list open files”, which is used in many Unix-like systems to report a list of all open files and the processes that opened them. This open source utility was developed and supported by Victor A. Abell, the retired Associate Director of the Purdue University Computing Center. It works in and supports several Unix flavors.

Useful Commands:

List all network connections:

 sudo lsof -i 

SSH:

sudo lsof -i:22
sudo lsof -c ssh

List all network files in use by a specific process:

 sudo lsof -i -a -p 1278 

List processes which are listening on a particular port:

 sudo lsof -i :25 

List all TCP or UDP connections:

 sudo lsof -i tcp; lsof -i udp; 

List processes which opened a specific file:

 lsof /var/log/syslog 

List opened files under a directory:

 lsof +D /var/log/ 

List opened files based on process names starting with:

 lsof -c ssh -c init 

List processes using a mount point:

 sudo lsof /home 

List files opened by a specific user:

 lsof -u keith 

What commands is user Keith using:

 sudo lsof -i -u keith 

List all open files by a specific process:

 lsof -p 1278 

Kill all process that belongs to a particular user:

 kill -9 `lsof -t -u keith` 

 

SSL Server Test

Qualys SSL Server Test is free online service that performs a deep analysis of the configuration of any SSL web server on the public Internet.

https://www.ssllabs.com/ssltest/

To configure Apache and Nginx with acceptable protocols TLS settings follow these guides, they will provide a better score on the above Qualys rating and make your SSL site more secure.

 

Snapcraft

Package any app for any Linux desktop, server, cloud or device.

A ‘snap’ is a universal Linux package

Snaps work on any distribution or device. Snaps are faster to install, easier to create, safer to run, and they update automatically and transactionally so your app is always fresh and never broken.

The public collection of snaps includes the latest and best apps from GitHub and beyond, so you have the whole world of Linux apps at your fingertips. Take the tour below to experience ‘hello world’ as a snap, or jump to the developer guide to create your own snaps.

Reference: http://snapcraft.io/

netdata real-time performance monitoring for Linux

Netdata is a real-time performance monitoring solution.

Unlike other solutions that are only capable of presenting statistics of past performance, netdata is designed to be perfect for real-time performance troubleshooting.

Netdata is a linux daemon you run, which collects data in realtime (per second) and presents a web site to view and analyze them. The presentation is also real-time and full of interactive charts that precisely render all collected values.

Netdata has been designed to be installed on every system, without disrupting the applications running on it:

  • It will just use some spare CPU cycles (check Performance).
  • It will use the memory you want it have (check Memory Requirements).
  • Once started and while running, it does not use any disk I/O, apart its logging (check Log Files). Of course it saves its DB to disk when it exits and loads it back when it starts.
  • You can use it to monitor all your systems and applications. It will run on Linux PCs, servers or embedded devices.

Out of the box, it comes with plugins that collect key system metrics and metrics of popular applications.

Available here: https://github.com/firehol/netdata

Midnight Commander file size format

When dealing with large files in MC, I have difficulties counting the digits to get the order of magnitude of the file size (hundreds of MB, or tens of GB, etc.). Sometimes, I use the trick to press insert key, which highlights the file and shows the file size in a nicely formatted way (i.e. 123,456,789), which makes it a thousand times more readable.

You can modify the configuration:

You can adjust the displayed digits with the column size option, see the “Listing mode” section in the manual. The file to edit is ~/.config/mc/panels.ini.

To list the file sizes as K, M or G use a narrow size column using the user_format key:

[New Left Panel]
user_format=half type name mark size:4 space mtime