ipcalc – bash IP Calculator

ipcalc takes an IP address and netmask and calculates the resulting broadcast, network, Cisco wildcard mask, and host range. By giving a second netmask, you can design subnets and supernets. It is also intended to be a teaching tool and presents the subnetting results as easy-to-understand binary values.

Enter your netmask(s) in CIDR notation (/25) or dotted decimals ( Inverse netmasks are recognized. If you omit the netmask ipcalc uses the default netmask for the class of your network. Look at the space between the bits of the addresses: The bits before it are the network part of the address, the bits after it are the host part. You can see two simple facts: In a network address all host bits are zero, in a broadcast address they are all set.




ipcalc is available from most Linux distro’s repo’s and from brew on mac’s.

man ipcalc

Anchore – Container Security Analysis

Anchore provides you with insight and control over the contents of your containers from the start of development all the way to production. Anchore delivers container security solutions for developers, operations, and security teams to deliver insight and control over the contents, security and compliance of containers from the start of development all the way to production. By allowing the creation of policies for security and compliance that are evaluated by Anchore at each stage of the build pipeline, Anchore ensures that only images containers that adhere to an organisation’s policies are deployed.

What’s Inside Your Container Images?
With Docker and containers it’s never been easier to deploy and run any application. Developers now have access to thousands of applications ready to run right “off the shelf” and the ability to quickly build and publish their own images.

In addition to the application, the container image may contain hundreds of packages and thousands of files including binaries, shared libraries, configuration files, and 3rd party modules. Any one of these components may contain a security vulnerability, an outdated software module, a misconfigured configuration file or simply fail to comply with your operational or security best practices.

For more details and to download/install:

AD Powershell

After running Windows Server 2016 recently with a DC, I’ve started using Powershell to perform AD functions. Here are a few basics.

New-ADUser cmdlet to create a new user:

 New-ADUser -Name John.Smith 

The above would only create the username, create a new user with more associations:

 New-ADUser -Name John Smith -GivenName John -Surname Smith -Path "OU=Staff,DC=Company,DC=Com" 

Add the password for above account:

 $password = "Strong Password" | ConvertTo-SecureString -AsPlainText -Force
New-ADUser -Name John.Smith -GivenName John -Surname Smith -Path "OU=Staff,DC=Company,DC=Com" 

Bulk Import Users with New-ADUser:

$Import =Import-CSV "c:\utils\aduserimport.csv"
$OU = "OU=staff,DC=ausinfotech,DC=local"
Foreach ($user in $Import)
$password = $user.Password | ConvertTo-SecureString -AsPlainText -Force
New-ADUser -Name $user.Name -GivenName $user.FirstName -Surname $user.LastName -Path $OU -AccountPassword $Password -ChangePasswordAtLogon $True -Enabled $True

The above script imports the CSV file, sets the standard OU and calls each data record (line of your CSV), writes the password and creates the user account. We are using a “Foreach”-loop, which loads each user record with its parameters from the CSV file.

See here for more info:

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.


# 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
# 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 $clist
echo "Updating Debian/Ubuntu container hypervisor \"$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



Reset Juniper SSG firewall password

If you are faced with not knowing the admin password for a Juniper SSG based firewall, you can reset to factory defaults. Ideally you should have been backing up the configuration and keeping your password safe with a password manager – if not and/or you have been provided with  an SSG or purchased from Ebay etc read on….

Console Cable Option:

  1. Connect via Console cable.
  2. Login with the serial number of the SSG as the username and password.
  3. You can reset the firewall to factory defaults.

Connect a network cable to Ethernet 0/0 and login via your browser to:
Username: netscreen
Password: netscreen

Reset the unit with reset pin:

Push and hold the pinhole on the Juniper. The status LED will turn to a blinking amber so KEEP holding, and when it turns to blinking green, release the pinhole. After 1 second, push and HOLD the pinhole again. The LED will turn to blinking red so KEEP holding until the status LED turns to solid amber or solid green, release right away and wait for the device to reset and come back – give it five minutes.
Then connect to it as described above

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 


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.


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.


Penetration Testing Tools Cheat Sheet

Penetration testing tools cheat sheet, a quick reference high level overview for typical penetration testing engagements. Designed as a quick reference cheat sheet providing a high level overview of the typical commands you would run when performing a penetration test. For more in depth information I’d recommend the man file for the tool or a more specific pen testing cheat sheet.

Site and other tools from: https://highon.coffee/blog/penetration-testing-tools-cheat-sheet/

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