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How to Install and Use auditd for System Security Auditing on Linux

Thursday, September 25th, 2025

System auditing is essential for monitoring user activity, detecting unauthorized access, and ensuring compliance with security standards. On Linux, the Audit Daemon (auditd) provides powerful auditing capabilities for logging system events and actions.

This short article will walk you through installing, configuring, and using auditd to monitor your Linux system.

What is auditd?

auditd is the user-space component of the Linux Auditing System. It logs system calls, file access, user activity, and more — offering administrators a clear trail of what’s happening on the system.


1. Installing auditd

The auditd package is available by default in most major Linux distributions.

 On Debian/Ubuntu

# apt update
# apt install auditd audispd-plugins

 On CentOS/RHEL/Fedora

# yum install audit

After installation, start and enable the audit daemon

# systemctl start auditd

# systemctl enable auditd

Check its status

# systemctl status auditd

2. Setting Audit Rules

Once auditd is running, you need to define rules that tell it what to monitor.

Example: Monitor changes to /etc/passwd

# auditctl -w /etc/passwd -p rwxa -k passwd_monitor

Explanation:

  • -w /etc/passwd: Watch this file. When the file is accessed, the watcher will generate events.
  • -p rwxa: Monitor read, write, execute, and attribute changes
  • -k passwd_monitor: Assign a custom key name to identify logs. Later on, we could search for this (arbitrary) passwd string to identify events tagged with this key.

List active rules:

# auditctl -l

3. Common auditd Rules for Security Monitoring

Here are some common and useful auditd rules you can use to monitor system activity and enhance Linux system security. These rules are typically added to the /etc/audit/rules.d/audit.rules or /etc/audit/audit.rules file, depending on your system.

a. Monitor Access to /etc/passwd and /etc/shadow
 

-w /etc/passwd -p wa -k passwd_changes
-w /etc/shadow -p wa -k shadow_changes

  • Monitors read/write/attribute changes to password files.

b. Monitor sudoers file and directory
 

-w /etc/sudoers -p wa -k sudoers
-w /etc/sudoers.d/ -p wa -k sudoers

  • Tracks any change to sudo configuration files.

c. Monitor Use of chmod, chown, and passwd
 

-a always,exit -F arch=b64 -S chmod -S fchmod -S fchmodat -k perm_mod
-a always,exit -F arch=b64 -S chown -S fchown -S fchownat -k perm_mod
-a always,exit -F arch=b64 -S passwd -k passwd_changes

  • Watches permission and ownership changes.

d. Monitor User and Group Modifications

-w /etc/group -p wa -k group_mod
-w /etc/gshadow -p wa -k gshadow_mod
-w /etc/security/opasswd -p wa -k opasswd_mod

  • Catches user/group-related config changes.

e. Track Logins, Logouts, and Session Initiation

-w /var/log/lastlog -p wa -k logins
-w /var/run/faillock/ -p wa -k failed_login
-w /var/log/faillog -p wa -k faillog

  • Tracks login attempts and failures.

f. Monitor auditd Configuration Changes

-w /etc/audit/ -p wa -k auditconfig
-w /etc/audit/audit.rules -p wa -k auditrules

  • Watches changes to auditd configuration and rules.

g. Detect Changes to System Binaries

-w /bin/ -p wa -k bin_changes
-w /sbin/ -p wa -k sbin_changes
-w /usr/bin/ -p wa -k usr_bin_changes
-w /usr/sbin/ -p wa -k usr_sbin_changes

  • Ensures core binaries aren't tampered with.

h. Track Kernel Module Loading and Unloading

-a always,exit -F arch=b64 -S init_module -S delete_module -k kernel_mod

  • Detects dynamic kernel-level changes.

l. Monitor File Deletions

-a always,exit -F arch=b64 -S unlink -S unlinkat -S rename -S renameat -k delete

  • Tracks when files are removed or renamed.

m. Track Privilege Escalation via setuid/setgid

-a always,exit -F arch=b64 -S setuid -S setgid -k priv_esc

  • Helps detect changes in user or group privileges.

n. Track Usage of Dangerous Binaries (e.g., su, sudo, netcat)

-w /usr/bin/su -p x -k su_usage
-w /usr/bin/sudo -p x -k sudo_usage
-w /bin/nc -p x -k netcat_usage

  • Useful for catching potentially malicious command usage.

o. Monitor Cron Jobs

-w /etc/cron.allow -p wa -k cron_allow
-w /etc/cron.deny -p wa -k cron_deny
-w /etc/cron.d/ -p wa -k cron_d
-w /etc/crontab -p wa -k crontab
-w /var/spool/cron/ -p wa -k user_crontabs

  • Alerts on cron job creation/modification.

p. Track Changes to /etc/hosts and DNS Settings

-w /etc/hosts -p wa -k etc_hosts
-w /etc/resolv.conf -p wa -k resolv_conf

  • Monitors potential redirection or DNS manipulation.

q. Monitor Mounting and Unmounting of Filesystems

-a always,exit -F arch=b64 -S mount -S umount2 -k mounts

  • Useful for detecting USB or external drive activity.

r. Track Execution of New Programs

-a always,exit -F arch=b64 -S execve -k exec

  • Captures command execution (can generate a lot of logs).
     

A complete list of rules you can get from the hardening.rules auditd file place it under /etc/audit/rules.d/hardening.rules
and reload auditd to load the configurations.

Tips

  • Use ausearch -k <key> to search audit logs for matching rule.
  • Use auditctl -l to list active rules.
  • Use augenrules –load after editing rules in /etc/audit/rules.d/.


4. Reading Audit Logs

Audit logs events are stored in:

/var/log/audit/audit.log

By default, the location, this can be changed through /etc/auditd/auditd.conf

View recent entries:
 

# tail -f /var/log/audit/audit.log

Search by key:
 

# ausearch -k passwd_monitor

Generate a summary report:

# aureport -f

# aureport


Example: Show all user logins / IPs :

# aureport -au

 

5. Making Audit Rules Persistent

Rules added with auditctl are not persistent and will be lost on reboot. To make them permanent:

Edit the audit rules configuration:

# vim /etc/audit/rules.d/audit.rules

Add your rules, for example:

-w /etc/passwd -p rwxa -k passwd_monitor

Apply the rules:

# augenrules –load

7. Some use case examples of auditd in auditing Linux servers by sysadmins / security experts
 

Below are real-world, practical examples where auditd is actively used by sysadmins, security teams, or compliance officers to detect suspicious activity, meet compliance requirements, or conduct forensic investigations.

a. Detect Unauthorized Access to /etc/shadow

Use Case: Someone tries to read or modify password hashes.

Audit Rule:

-w /etc/shadow -p wa -k shadow_watch

Real-World Trigger:

sudo cat /etc/shadow

Check Logs:
 

# ausearch -k shadow_watch -i

Real Output:
 

type=SYSCALL msg=audit(09/18/2025 14:02:45.123:1078):

  syscall=openat

  exe="/usr/bin/cat"

  success=yes

  path="/etc/shadow"

  key="shadow_watch"

b. Detect Use of chmod to Make Files Executable

Use Case: Attacker tries to make a script executable (e.g., malware).

Audit Rule:

-a always,exit -F arch=b64 -S chmod -k chmod_detect

Real-World Trigger:
 

 # chmod +x /tmp/evil_script.sh

Check Logs:

# ausearch -k chmod_detect -i

c. Monitor Execution of nc (Netcat)

Use Case: Netcat is often used for reverse shells or unauthorized network comms.

Audit Rule:
 

-w /bin/nc -p x -k netcat_usage
 

Real-World Trigger:

nc -lvp 4444

Log Entry:

type=EXECVE msg=audit(09/18/2025 14:35:45.456:1123):

  argc=3 a0="nc" a1="-lvp" a2="4444"

  key="netcat_usage"

 

d. Alert on Kernel Module Insertion
 

Use Case: Attacker loads rootkit or malicious kernel module.

Audit Rule:

-a always,exit -F arch=b64 -S init_module -S delete_module -k kernel_mod

Real-World Trigger:

# insmod myrootkit.ko

Audit Log:
 

type=SYSCALL msg=audit(09/18/2025 15:00:13.100:1155):

  syscall=init_module

  exe="/sbin/insmod"

  key="kernel_mod"

e. Watch for Unexpected sudo Usage

Use Case: Unusual use of sudo might indicate privilege escalation.

Audit Rule:

-w /usr/bin/sudo -p x -k sudo_watch

Real-World Trigger:

sudo whoami

View Log:
 

# ausearch -k sudo_watch -i


f. Monitor Cron Job Modification

Use Case: Attacker schedules persistence via cron.

Audit Rule:

-w /etc/crontab -p wa -k cron_mod

Real-World Trigger:
 

echo "@reboot /tmp/backdoor" >> /etc/crontab

Logs:
 

type=SYSCALL msg=audit(09/18/2025 15:05:45.789:1188):

  syscall=open

  path="/etc/crontab"

  key="cron_mod"

g. Detect File Deletion or Renaming
 

Use Case: Attacker removes logs or evidence.

Audit Rule:

-a always,exit -F arch=b64 -S unlink -S unlinkat -S rename -S renameat -k file_delete

Real-World Trigger:

# rm -f /var/log/syslog

Logs:
 

type=SYSCALL msg=audit(09/18/2025 15:10:33.987:1210):

  syscall=unlink

  path="/var/log/syslog"

  key="file_delete"


h. Detect Script or Malware Execution
 

Use Case: Capture any executed command.

Audit Rule:
 

-a always,exit -F arch=b64 -S execve -k exec

Real-World Trigger:

/tmp/myscript.sh

Log View:

# ausearch -k exec -i | grep /tmp/myscript.sh

l. Detect Manual Changes to /etc/hosts

Use Case: DNS hijacking or phishing setup.

Audit Rule:

-w /etc/hosts -p wa -k etc_hosts

Real-World Trigger:
 

# echo "1.2.3.4 google.com" >> /etc/hosts

Logs:

type=SYSCALL msg=audit(09/18/2025 15:20:11.444:1234):

  path="/etc/hosts"

  syscall=open

  key="etc_hosts"


8. Enable Immutable Mode (if necessery)

For enhanced security, you can make audit rules immutable, preventing any changes until reboot:

# auditctl -e 2


To make this setting persistent, add the following to the end of /etc/audit/rules.d/audit.rules:

-e 2


Common Use Cases

Here are a few more examples of what you can monitor:

Monitor all sudo usage:

# auditctl -w /var/log/auth.log -p wa -k sudo_monitor


Monitor a directory for file access:

# auditctl -w /home/username/important_dir -p rwxa -k dir_watch

Audit execution of a specific command (e.g., rm):

# auditctl -a always,exit -F arch=b64 -S unlink,unlinkat -k delete_cmd

(Adjust arch=b64 to arch=b32 if on 32-bit system.)

9. Managing the Audit Log Size

Audit logs can grow large over time. To manage log rotation and size, edit:
 

# vim /etc/audit/auditd.conf

Set log rotation options like:

max_log_file = 8

num_logs = 5

Then restart auditd:
 

# systemctl restart auditd

Conclusion

The Linux Audit Daemon (auditd) is a powerful tool to track system activity, enhance security, and meet compliance requirements. With just a few configuration steps, you can monitor critical files, user actions, and system behavior in real time.

 

References

  • man auditd
  • man auditctl
  • Linux Audit Wiki

 

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Posted in Computer Security, Linux, Monitoring | No Comments »

How to install BASH and use shell scripting on Windows ?

Thursday, June 26th, 2025

install-bash-on-windows-run-and-use-shellscripting-on-windows-howto

Bash (Bourne Again SHell) is definitely a technology that will stay for years to come its simplicity and multi-platoformness is a factor that will definitely continue for many years thus even though it is mostly used on Linux / BSD / Unix, its application on Windows OS-es nowadays is perhaps increasing. Hence since so many people use Winodws nowdays (for work) it is really useful to have Bash set-up on Windows host machine.
In this article, I'll shortly explain how this is done, the article will not have anything too much interesting for the advanced admin or dev ops guy, but I hope people who are entering the business of system administration and high level computing and still orienting might benefit from it.

To install and use Bash shell terminal in Windows there are at least 3 ways:

  • Use Git Bash (Download and install it directly precompiled on WIndows)
  • Use Windows WSL emulation (install some Linux distro)
  • Use Virtualbox / Vagrant / VMware / Hyper-V emulation and install VM from public ISO image.

As a Free Software Lover, I would recommend and  always prefer to use the Free Software alternative if that is possible and thanksfully usually I use and install Git Bash or completely install Cygwin (Full set of Linux tools to run like native on Windows together with  Mobaxterm) together.

 

1. Installing Git Bash on Windows (uses MinGW Minimalist GNU for Windows)

Some might prefer to not use Microsoft for managing their bash especially the more freedom in mind people who like GNU and Free software and people.

MinGW is well known among free and open source enthusiasts.
It includes a port of the GNU Compiler Collection (GCC), GNU Binutils for Windows (assembler, linker, archive manager), a set of freely distributable Windows specific header files and static import libraries which enable the use of the Windows API, a Windows native build of the GNU Project's GNU Debugger, and miscellaneous utilities.

MinGW does not rely on third-party C runtime dynamic-link library (DLL) files, and because the runtime libraries are not distributed using the GNU General Public License (GPL), it is not necessary to distribute the source code with the programs produced, unless a GPL library is used elsewhere in the program.

 

MinGW can be run either on the native Microsoft Windows platform, cross-hosted on Linux (or other Unix), or "cross-native" on Cygwin.


To install Bash via Git, you can use Git for Windows, which includes Git Bash — a lightweight Bash emulator.


Steps to Install Git Bash on Windows
 

a. Download Git for Windows

Go to the official Git website:

https://git-scm.com/download/win

The download should start automatically.

b. Run the Installer

  • Open the downloaded .exe file
  • Follow the installation prompts

Recommended Settings:

  • Select components: Keep default
  • Editor: Choose your preferred text editor (e.g., Notepad++ or Vim)
  • Adjust PATH environment: Choose “Git from the command line and also from 3rd-party software”
  • Choose SSH executable: Use Built-in OpenSSH
  • Choose HTTPS transport backend: Use the default (OpenSSL)
  • Configure line endings: Select “Checkout Windows-style, commit Unix-style line endings”
  • Terminal emulator: Choose “Use MinTTY (the default terminal)”

Click Next through the remaining steps and then Install.

c. Launch Git Bash

After installation:

  • Press Windows key, type "Git Bash"
  • Click to launch the terminal

Now you're using a Bash shell on Windows.

Perhaps most common way is to use Windows Subsystem for Linux (WSL), people follow. WSL is a technology which is native Windows but gives MS Windows the opportunity to act in a way similar to docker containers. WSL lets you run a full Linux environment (including Bash) directly on Windows without using a virtual machine and is really fast and easy on Machine system resources. 


 2. Installing WSL bash easy from Windows 10 / 11 using  Win GUI menus


Steps to install WSL on Windows 10 / 11

Microsoft has since only continued to improve its Windows Subsystem for Linux, and an update in a Windows 10 preview build back in mid-2020 made it easier to install Bash.

That method also works the same as on Win 10 as well as on Win 11.
To install Bash shell emulation, hence open Windows Terminal as an admin user. You can do this by right-clicking the Windows icon and selecting “Windows Terminal (Admin)” from the power user menu.

(If you’re on Windows 10, you should see it listed as “Windows Powershell (Admin)” in the menu.)

 

windows-run-powershell-from-start-menu-screenshot

 


To complete WSL install with Virtualized Ubuntu OS

In Windows Terminal, run this command:

PS C:\Users\MyUser> wsl –install

Once everything is downloaded needed to run WSL emulation and Ubuntu Linux distribution,  Restart the PC.

Once your PC rebooted, installation will continue automatically.

After Ubuntu installed successfully, you’ll next be prompted to create a username and password and Ubuntu will fire up, and you will have your bash in Windows

 

Install-WSL-linux-subsystem-for-windows-from-powershell-prompt-screenshot


a. Enabling and Intalling BASH via command line (if WSL Linux subsystem for Windows is not enabled on Windows


It might be your Windows has no configured Windows Subsystem for Linux, hence if that is the case you will need to enable it following below few steps.

b. Enable WSL via dism.exe cmd

Open PowerShell as Administrator and run:

Powershell

PS C:\Users\MyUser> wsl –install

This installs WSL 2 and a default Linux distribution (like Ubuntu).

If you're on Windows 10 or on a PC where whoever installed the OS has not installed the Win Subsystem for Linux, you may need to manually enable WSL:

Launch Powershell

PS C:\Users\MyUser> dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart

PS C:\Users\MyUser> dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart

Then restart your computer and run:

from the Windows Magnifier run Powershell and type in PS1 prompt:

PS C:\Users\MyUser> wsl –set-default-version 2

c. Installing other Linux Distribution (different from Ubuntu)

If not already installed during wsl –install, open the Microsoft Store and search for:

  • Ubuntu
  • Debian
  • Kali Linux
  • etc.

Click Install on the one you want.

d. Launching WSL / Bash terminal

Once installed:

  • Open Start Menu
  • Search for your Linux distro you just installed (e.g., “Ubuntu”)
  • Launch it

This opens a Bash shell where you can run Linux commands, like in regular Linux but on your Microsoft Windows OS.
 

Sum it up

What we learned is how to install bash via Bash Git and start using it to have more hybrid environment Windows / Linux. The article explained the two main methods using GIt Bash and using embedded Windows emulator WSL with an emulated Linux distro.

Enjoy ! 🙂

 

 


 

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Posted in Curious Facts, Everyday Life, System Administration, Windows | No Comments »

How to Install ssh client / server on Windows 10, Windows Server 2019 and Windows Server 2022 using PowerShell commands

Wednesday, March 2nd, 2022

How-to-install-OpenSSH-Client-and-Server-on-Windows-10-Windows-Server-2022-Windows-2019-via-command-line-Powershell

Historically to have a running ssh client on Windows it was required to install CygWin or MobaXterm as told in my previous articles Some Standard software programs to install on Windows to make your Desktop feel  more Linux / Unix Desktop and Must have software on Freshly installed Windows OS.
Interesting things have been developed on the Windows scene since then and as of year 2022 on Windows 10 (build 1809 and later) and on Windows 2019, Windows Server 2022, the task to have a running ssh client to use from cmd.exe (command line) became trivial and does not need to have a CygWin Collection of GNU and Open Source tools installed but this is easily done via Windows embedded Apps & Features GUI tool:

To install it from there on 3 easy steps:

 

  1. Via  Settings, select Apps > Apps & Features, then select Optional Features.
  2. Find OpenSSH Client, then click Install
  3. Find OpenSSH Server, then click Install


For Windows domain administrators of a small IT company that requires its employees for some automated script to run stuff for example to tunnel encrypted traffic from Workers PC towards a server port for example to secure the 110 POP Email clients to communicate with the remote Office server in encrypted form or lets say because ssh client is required to be on multiple domain belonging PCs used as Windows Desktops by a bunch of developers in the company it also possible to use PowerShell script to install the client on the multiple Windows machines.

Install OpenSSH using PowerShell
 

To install OpenSSH using PowerShell, run PowerShell as an Administrator. To make sure that OpenSSH is available, run the following cmdlet in PowerShell

Get-WindowsCapability -Online | Where-Object Name -like 'OpenSSH*'


This should return the following output if neither are already installed:

 

Name  : OpenSSH.Client~~~~0.0.1.0
State : NotPresent

Name  : OpenSSH.Server~~~~0.0.1.0
State : NotPresent


Then, install the server or client components as needed:

Copy in PS cmd window

# Install the OpenSSH Client
Add-WindowsCapability -Online -Name OpenSSH.Client~~~~0.0.1.0

# Install the OpenSSH Server
Add-WindowsCapability -Online -Name OpenSSH.Server~~~~0.0.1.0


Both of these should return the following output:
 

Path          :
Online        : True
RestartNeeded : False


If you want to also allow remote access via OpenSSH sshd daemon, this is also easily possible without installing especially an openssh-server Windows variant !

Start and configure OpenSSH Server

To start and configure OpenSSH Server for initial use, open PowerShell as an administrator, then run the following commands to start the sshd service:

# Start the sshd service
Start-Service sshd

# OPTIONAL but recommended:
Set-Service -Name sshd -StartupType 'Automatic'

# Confirm the Firewall rule is configured. It should be created automatically by setup. Run the following to verify
if (!(Get-NetFirewallRule -Name "OpenSSH-Server-In-TCP" -ErrorAction SilentlyContinue | Select-Object Name, Enabled)) {
    Write-Output "Firewall Rule 'OpenSSH-Server-In-TCP' does not exist, creating it…"
    New-NetFirewallRule -Name 'OpenSSH-Server-In-TCP' -DisplayName 'OpenSSH Server (sshd)' -Enabled True -Direction Inbound -Protocol TCP -Action Allow -LocalPort 22
} else {
    Write-Output "Firewall rule 'OpenSSH-Server-In-TCP' has been created and exists."
}


Connect to OpenSSH Server
 

Once installed, you can connect to OpenSSH Server from a Windows 10 or Windows Server 2019 device with the OpenSSH client installed using PowerShell or Command Line tool as Administrator and use the ssh client like you would use it on any *NIX host.

C:\Users\User> ssh username@servername


The authenticity of host 'servername (10.10.10.1)' can't be established.
ECDSA key fingerprint is SHA256:(<a large string>).
Are you sure you want to continue connecting (yes/no)?
Selecting yes adds that server to the list of known SSH hosts on your Windows client.

You are prompted for the password at this point. As a security precaution, your password will not be displayed as you type.

Once connected, you will see the Windows command shell prompt:

Domain\username@SERVERNAME C:\Users\username>

 

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Posted in System Administration, Windows | No Comments »

Set proxy only for apt, apt-get, aptitude package manager on Debian / Ubuntu Linux

Wednesday, December 22nd, 2021

debian-package-manager-run-via-a-proxy

 

Intro

Main console package install apt-get / apt and / aptitude did not use the HTTP Proxy environment variables by default as there is no default proxy set on Debian / Ubuntu / Mint and other deb based distros after OS Install. Under some circunstances for DMZ placed or firewall secured servers, direct access to internet address or even Package repository is only allowed via a proxy and hence the package manager needs to have a proxy host set.
 Setting a global wide proxy on Linux is easily possible by setting http_proxy="http://yourhost.com:8080" and https_proxy or if FTP connection via ftp_proxy somewhere in /etc/profile , /etc/bashrc or via /etc/environment but as using this Shell variables set it global wide for all applications lynx / links / wget / curl, sometimes it is useful to set the Proxy host only for deb package management tools.

Note that if you want to set a proxy host for deb operations this can be done during initial OS install installation, the Apt configuration file would have been automatically updated then. 

Creating  an Apt Proxy Conf File

Apt loads all configuration files under /etc/apt/apt.conf.d. We can create a configuration specifically for our proxy there, keeping it separate from all other configurations.

  1. Create a new configuration file named proxy.conf.

     

      

    # touch /etc/apt/apt.conf.d/proxy.conf
  2. Open the proxy.conf file in a text editor.

     

      

    # vi /etc/apt/apt.conf.d/proxy.conf
  3. Add the following line to set your HTTP proxy for apt.

     

      

    Acquire::http::Proxy "http://username:password@proxy.server:port/";
  4. Add the following line to set your HTTPS proxy.

     

      

    Acquire::https::Proxy "http://username:passw0rd@proxy.server:port/";
  5. Save your changes and exit the text editor.
     

Your proxy settings will be applied the next time you run Apt.

Simplifying the Configuration

As mentioned by a user in the comments below, there is an alternative way for defining the proxy settings. While similar, it removes some redundancy.

Just like in the first example, create a new file under the /etc/apt/apt.conf.d directory for example /etc/apt/apt.conf.d/proxies, and then add the lines as. 

Acquire {
  HTTP::proxy "http://127.0.0.1:8080";
  HTTPS::proxy "http://127.0.0.1:8080";
}

 

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Posted in Debian, Linux | No Comments »

Build and install Docker Squid Open Proxy image on Kubernetes cluster

Tuesday, October 30th, 2018

docker_container-virtualization-install-open-squid-cache-logo

As Docker containerization is starting to become a standard for installing a brand new servers especially servers who live in Self-Made Clusters based on Orchestration technologites like Kubernetes (k8s) (check out – http://kubernetes.io),

Recently, I've had the task to set-up a Squid Cache (Open Proxy) server on a custom Port number to make it harder for internet open proxy scanners to identify and ship it to a customer.

What is Squid Open Proxy?

An open proxy is a proxy server that is accessible by any Internet user, in other words anyone could access the proxy without any authentication.

Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP and other protocols.
It reduces bandwidth and improves response times by caching and reusing frequently-requested web pages.
Squid has extensive access controls and makes a great server accelerator.
It runs on most available operating systems, including Windows and is licensed under the GNU GPL.
 

What is Docker?

For those who hear about Docker for a first time, Docker is an open-source software platform to create, deploy and manage virtualized application containers on a common OS such as GNU / Linux or Windows, it has a surrounding ecosystem of tools. Besides its open source version there is also a commercial version of the product by Docker Inc. the original company that developed docker and is today in active help of the project.

docker-engine-components-explained-flow
Docker components  – picture source docker.com

What is Kubernetes?
 

Kubernetes, in short, is an open source system for managing clusters of containers. To do this, it provides tools for deploying applications, scaling those application as needed, managing changes to existing containerized applications, and helps you optimize the use of the underlying hardware beneath your containers.
Kubernetes is designed to be extensible and fault-tolerant by allowing application components to restart and move across systems as needed.
 

Kubernetes is itself not a Platform as a Service (PaaS) tool, but it serves as more of a basic framework, allowing users to choose the types of application frameworks, languages, monitoring and logging tools, and other tools of their choice. In this way, Kubernetes can be used as the basis for a complete PaaS to run on top of; this is the architecture chosen by the OpenShift Origin open source project in its latest release.

Kubernetes-cloud-app-architecture
Kubernetes architecture (shortly explained) – picture source Wikipedia

The Kubernetes project is written in the Google developed Go programming language, and you can browse its source code on GitHub.


Hence, In this article I'll give a brief introuduction on what is Docker and show you, how to easily:

a. Build Docker Image with Ubuntu, Update the system and Install Squid inside the container
using a sample Dockerfile build file

b. Run Docker Image to test deployed Ubuntu Linux and Squid on top of it works fine

c. Push Docker Image to DockerHub (Docker Images Central Official repository)

d. Deploy (Pull and Run) the new built Docker Ubuntu / Squid Open Proxy Image to the Kubernetes Cluster slave nodes – the K8S Cluster was  created using Rancher Enterprise Kubernetes Platform (check out Rancher.net – a bleeding edge tool for k8s quick GUI cluster creation / integration)
 

1. Install Docker Containerization Software Community Edition


Docker containers are similar to virtual machines, except they run as normal processes (containers), that does not use a Hypervisor of Type 1 or Type 2 and consume less resources than VMs and are easier to manage, nomatter what the OS environment is.

Docker uses cgroups and namespace to allow independent containers to run within a single Linux instance.

docker-architecture-explained
Docker Architecture – Picture source docker.com

Below docker install instructions are for Debian / Ubuntu Linux, the instructions for RPM package distros Fedora / CentOS / RHEL are very similar except yum or dnf tool is to be used.

a) Uninstall older versions of docker , docker-engine if present
 

 

apt-get -y remove docker docker-engine docker.io

 

! Previously running docker stuff such as Volumes, Images and networks will be preserved in /var/lib/docker/

b) install prerequired packages and add apt repositories for doko
 

apt-get update
apt-get install -y apt-transport-https ca-certificates wget software-properties-common

 

wget https://download.docker.com/linux/debian/gpg
apt-key add gpg
rm -f gpg

 

Create docker.list apt sources file

 

echo "deb [arch=amd64] https://download.docker.com/linux/debian $(lsb_release -cs) stable" | sudo tee -a /etc/apt/sources.list.d/docker.list

 

apt-get update

 

c) check out the docker policy (will list you a multiple installable versoins of docker).

 

apt-cache policy docker-ce

docker-ce:
  Installed: (none)
  Candidate: 17.06.0~ce-0~debian
  Version table:
     17.06.0~ce-0~debian 500
        500 https://download.docker.com/linux/debian stretch/stable amd64 Packages
     17.03.2~ce-0~debian-stretch 500
        500 https://download.docker.com/linux/debian stretch/stable amd64 Packages
     17.03.1~ce-0~debian-stretch 500
        500 https://download.docker.com/linux/debian stretch/stable amd64 Packages
     17.03.0~ce-0~debian-stretch 500

 

d) Install and run docker

 

apt-get -y install docker-ce
systemctl start docker

systemctl-docker-containerization-status-gnu-linux-screenshot

 

systemctl status docker

 

Previously running docker stuff such as Volumes, Images and networks will be preserved in /var/lib/docker/
 

2. Build Docker image with Ubuntu Linux OS and Squid inside


To build a docker image all you need to do is have the Dockerfile (which is docker definitions build file), an Official image of Ubuntu Linux OS (that is provided / downloaded from dockerhub repo) and a bunch of docker commands to use apt / apt-get to install the Squid Proxy inside the Docker Virtual Machine Container

In dockerfile it is common to define for use an entrypoint.sh  which is file with shell script commands definitions, that gets executed immediately after Docker fetches the OS from its remote repository on top of the newly run OS. It is pretty much like you have configured your own Linux distribution like using Linux from Scratch! to run on a bare-metal (hardware) server and part of the installation OS process you have made the Linux to run a number of scripts or commands during install not part of its regular installation process.

a) Go to https://hub.docker.com/ and create an account for free

The docker account is necessery in order to push the built docker image later on.
Creating the account creates just few minutes time.

Build-Docker-Images-with-DockerFile-diagram

b) Create a Dockerfile with definitions for Squid Open Proxy setup

I'll not get into details on the syntax that Dockerfile accepts, as this is well documented on Docker Enterprise Platform official website but in general gettings the basics and starting it is up to a 30 minutes to maximum 1h time.

 

After playing a bit to achieve the task to have my Linux distribution OS (Ubuntu Xenial) with Squid on installed on top of it with the right configuration of SQUID Cacher to serve as Open Proxy I've ended up with the following Dockerfile.

 

FROM ubuntu:xenial
LABEL maintainer="hipo@www.pc-freak.net"

ENV SQUID_VERSION=3.5.12-1ubuntu7 \
    SQUID_CACHE_DIR=/var/spool/squid \
    SQUID_LOG_DIR=/var/log/squid \
    SQUID_USER=proxy

RUN apt-get update \
 && apt-get upgrade && apt-get dist-upgrade && DEBIAN_FRONTEND=noninteractive apt-get install -y squid=${SQUID_VERSION}* \
 && rm -rf /var/lib/apt/lists/*

COPY entrypoint.sh /sbin/entrypoint.sh
COPY squid.conf /etc/squid/squid.conf
RUN chmod 755 /sbin/entrypoint.sh

EXPOSE 3128/tcp
ENTRYPOINT [“/sbin/entrypoint.sh”]

You can download the Dockerfile here.

c) Create entrypoint.sh and squid.conf files

Apart from that I've used the following entrypoint.sh (which creates and sets necessery caching and logging directories and launches script on container set-up) permissions for SQUID proxy  file that is loaded from the Dockerfile on docker image build time.
To have the right SQUID configuration shipped up into the newly built docker container, it is necessery to prepare a template configuration file – which is pretty much a standard squid.conf file with the following SQUID Proxy configuration for Open Proxy

 

acl SSL_ports port 443
acl CONNECT method CONNECT

 

http_access deny !Safe_ports

http_access deny CONNECT !SSL_ports

http_access allow localhost manager
http_access deny manager

 

http_access allow localhost

http_access allow all

http_port 3128


coredump_dir /var/spool/squid

refresh_pattern ^ftp:           1440    20%     10080
refresh_pattern ^gopher:        1440    0%      1440
refresh_pattern -i (/cgi-bin/|\?) 0     0%      0
refresh_pattern (Release|Packages(.gz)*)$      0       20%     2880
refresh_pattern .               0       20%     4320

 

Once, I've created, the proper Dockerfile configuration, I've made a tiny shell script, that can create / re-create my docker image multiple times. 
Here is the build-docker-image.sh :
 

#!/bin/sh
username='hipod';
password='';
docker login –username="$username" –password=""
DOCKER_ACC=hipod
#DOCKER_REPO=squid-3.5.12-1ubuntu7
DOCKER_REPO=squid-ubuntu
IMG_TAG=latest

docker build -t $DOCKER_ACC/$DOCKER_REPO:$IMG_TAG .
docker push $DOCKER_ACC/$DOCKER_REPO:$IMG_TAG


– You can download build-docker-image.sh script here

The script uses the docker login command to authenticate non-interactively to https://hub.docker.com
docker build command with properly set DOCKER_ACC (docker account – which is the username of your hub.docker.com account as I've pointed earlier in article), then DOCKER_REPO (docker repository name) – you can get it either from a browser, after you've logged in to dockerhub or assuming you know your username, it should look like:
https://hub.docker.com/u/your-username-name – for example mine is hipod with repository name squid-ubuntu, my squid-ubuntu docker image build is here, you'll also need to provide the password inside the script or if you consider it a security concern, instead type manually from command line docker login and authenticate in advance before running the script, finally the last line docker push pushes to remote docker hub the new build of Ubuntu + SQUID Proxy with a predefined TAG that in my case is latest (as this is my latest build of Squid – if you need a multiple version number of Squid repository just change the tag to the version tag line number.

 

d) Use the script to build Squid docker image

build-docker-image-terminal-screenshot-linux

Next run the script to make and push into docker your new image:
 

sh build-docker-image.sh

 

Please consider that in order to work with docker hub push / pull, you will need to have a firewall that allows connection to dockerhub site repo, if for some reason the push / pull fails, check closely your firewall as it is the most likely cause for failure.

 

3. Run the new docker image to test Squid runs as expected

To make sure the docker image runs properly, you can test it on any machine that has docker.io installed, this is done with a simple cmd:
 

docker run -d –restart=always -p 3128:3128 hipod/squid-ubuntu:latest

 


The -d option tells docker to background process / run in detached mode
 -p option tells docker to expose port (e.g. make NAT with iptables from the docker virtual container with Linux OS + SQUID listening inside the container on port 3128 to the TCP / IP 3128 server port).
You can use iptables to check the created Network Address Translation rules.

–restart=always option sets the docker restart policy (e.g. when the container is terminating it tells the container to restart the container (OS) after exit), there, you can use as a resetart policy (no, on-failure[:max_retries] , unless-stopped)

For clarity I've created one liner script run-squid.sh you can download here.
 

sh run-squid.sh

You can use a
 

ps aux|grep -i docker
 

root     13169  0.2  0.4 591300 77984 ?        Ssl  13:50   0:09 /usr/bin/dockerd -H fd://
root     13176  0.0  0.2 408244 34972 ?        Ssl  13:50   0:03 docker-containerd –config /var/run/docker/containerd/containerd.toml
root     20875  0.0  0.0 132348   948 pts/1    S+   14:52   0:00 grep -i docker


to see it running as well as the:

 

docker ps -a
 

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                      PORTS               NAMES
d2eb7ab635cf        c5b0f61227cd        "/bin/sh -c 'apt-get…"   12 minutes ago      Exited (1) 3 minutes ago                        trusting_elion
18476f546562        c5b0f61227cd        "/bin/sh -c 'apt-get…"   37 minutes ago      Exited (1) 37 minutes ago                       admiring_wilson


To connect to the running container later you can use docker attach ID_of_container

 

docker attach d2eb7ab635cf

 

 


command to see the new container runs as well as attach to the newly spawned container

 

4. Deploying Dockerized SQUID Open Proxy Cache server to Kubernetes cluster

 

My task was to deploy the newly built squid doko image to remote K8s cluster which was set as a default cluster via a context in  .kube/config/  or manually set via:

 

kubectl config use-context my.k8s-cluster.net


I've used the following YAML file with kubectl to deploy:

 

—
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  labels:
    app: squid-app-33128
  name: squid-app-33128
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: squid-app-33128
    spec:
      containers:
        – name: squid
          image: hipod/squid-ubuntu:latest
          imagePullPolicy: Always
          ports:
          – containerPort: 3128
            protocol: TCP
          volumeMounts:
            – mountPath: /var/spool/squid
              name: squid-cache
            – mountPath: /var/log/squid
              name: squid-log
          livenessProbe:
            tcpSocket:
              port: 3128
            initialDelaySeconds: 40
            timeoutSeconds: 4
      volumes:
        – name: squid-cache
          emptyDir: {}
        – name: squid-log
          emptyDir: {}


The task included to deploy two different Open Proxy squid servers on separate ports in order to add them external cluster Ingress load balancing via Amazon AWS, thus I actually used following 2 yaml files.

1. squid-app-33128.yaml
2. squid-app-33129.yaml

The actual deployment command was like that:

 

# deploys pods and adds services to kubernetes cluster

kubectl create -f squid-app-33129.yaml -f squid-app-33128.yaml -f squid-service-33129.yaml squid-service-33128.yaml

 

You can download the 2 squid-service .yaml below:

1. squid-service-33129.yaml
2. squid-service-33128.yaml

The service is externally exposed via later configured LoadBalancer to make the 2 squid servers deployed into k8s cluster accessible from the Internet by anyoneone without authorization (as a normal open proxies) via TCP/IP ports 33128 and 33129.
 

Conclusion


Below I explained a few easy steps to follow to;


– build docker image Ubuntu + Squid
– test the image
– deploy the image into a previously prepared k8s cluster

Though it all looks quite simplistic I should say creating the .yaml file took me long. Creating system configuration is not as simple as using the good old .conf files and getting used with the identation takes time.

Now once the LB are configured to play with k8s, you can enjoy the 2 proxy servers. If you need to do some similar task and you don't have to do it for a small fee, contact me.

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Posted in Cloud services, Docker, Educational | No Comments »

Installing the phpbb forum on Debian (Squeeze/Sid) Linux

Saturday, September 11th, 2010

howto-easily-install-phpbb-on-debian-gnu-linux

I've just installed the phpbb forum on a Debian Linux because we needed a goodquick to install communication media in order to improve our internal communication in a student project in Strategic HR we're developing right now in Arnhem Business School.

Here are the exact steps I followed to have a properly it properly instlled:

1. Install the phpbb3 debian package
This was pretty straight forward:

debian:~# apt-get install phpbb3

At this point of installation I've faced a dpkg-reconfigure phpbb deb package configuration issue:
I was prompted to pass in the credentials for my MySQL password right after I've selected the MySQL as my preferred database back engine.
I've feeded my MySQL root password as well as my preferred forum database name, however the database installation failed because, somehow the configuration procedure tried to connect to my MySQL database with the htcheck user.
I guess this has to be a bug in the package itself or something from my previous installation misconfigured the way the debian database backend configuration was operating.
My assumption is that my previously installed htcheck package or something beforehand I've done right after the htcheck and htcheck-php packages installation.

after the package configuration failed still the package had a status of properly installed when I reviewed it with dpkg
I've thought about trying to manually reconfigure it using the dpkg-reconfigure debian command and I gave it a try like that:

debian:~# dpkg-reconfigure phpbb3

This time along with the other fields I've to fill in the ncurses interface I was prompted for a username before the password prompted appeared.
Logically I tried to fill in the root as it's my global privileges MySQL allowed user.
However that didn't helped at all and again the configuration tried to send the credentials with user htcheck to my MySQL database server.
To deal with the situation I had to approach it in the good old manual way.

2. Manually prepare / create the required phpbb forum database

To completet that connected to the MySQL server with the mysql client and created the proper database like so:

debian:~# mysql -u root -p
mysql>
CREATE database phpbb3forum;

3. Use phpmyadmin or the mysql client command line to create a new user for the phpbb forum

Here since adding up the user using the phpmyadmin was a way easier to do I decided to go that route, anyways using the mysql cli is also an option.

From phpmyadmin It's pretty easy to add a new user and grant privileges to a certain database, to do so navigate to the following database:

Privileges -> -> Add a new user ->

Now type your User name: , Host , Password , Re-type password , also for a Host: you have to choose Local from the drop down menu.

Leave the Database for user field empty as we have already previously created our desired database in step 2 of this article

Now press the "Go" button and the user will get created.

Further after choose the Privileges menu right on the bottom of the page once again, select through the checkbox the username you have just created let's say the previously created user is phpbb3

Go to Action (There is a picture with a man and a pencil on the right side of this button

Scroll down to the page part saying Database-specific privileges and in the field Add privileges on the following database: fill in your previosly created database name in our case it's phpbb3forum

and then press the "Go" button once again.
A page will appear where you will have to select the exact privileges you would like to grant on the specific selected database.
For some simplicity just check all the checkbox to grant as many privilegs to your database as you could.
Then again you will have to press the "Go" button and there you go you should have already configured an username and database ready to go with your new phpbb forum.

4. Create a virtualhost if you would like to have the forum as a subdomain or into a separate domain

If you decide to have the forum on a separate sub-domain or domain as I did you will have to add some kind of Virtualhost into either your Apache configuration /etc/apache2/apache2.conf or into where officially the virutualhosts are laid in Debian Linux in /etc/apache2/sites-available
I've personally created a new file like for instance /etc/apache2/sites-available/mysubdomain.mydomain.com

Here is an example content of the new Virtualhost:

<VirtualHost *>
ServerAdmin admin-email@domain.com
ServerName mysubdomain.domain.com

# Indexes + Directory Root.
DirectoryIndex index.php index.php5 index.htm index.html index.pl index.cgi index.phtml index.jsp index.py index.asp

DocumentRoot /usr/share/phpbb3/www/

# Logfiles
ErrorLog /var/log/apache2/yourdomain/error.log
CustomLog /var/log/apache2/yourdomain/access.log combined
# CustomLog /dev/null combined
<Directory /usr/share/phpbb3/www/>
Options FollowSymLinks MultiViews -Includes ExecCGI
AllowOverride All
Order allow,deny
allow from all </Directory>
</VirtualHost>

In above Virtualhost just change the values for ServerAdmin , ServerName , DocumentRoot , ErrorLog , CustomLog and Directory declaration to adjust it to your situation.

5. Restart the Apache webserver for the new Virtualhost to take affect

debian:~# /etc/init.d/apache2 restart

Now accessing your http://mysubdomain.domain.com should display the installed phpbb3 forum
The default username and password for your forum you can use straight are:

username: admin
password: admin

So far so good you by now have the PHPBB3 forum properly installed and running, however if you try to Register a new user in the forum you will notice that it's impossible because of a terrible ugly message reading:

Sorry but this board is currently unavailable.

I've spend few minutes online to scrape through the forums before I can understand what I have to stop that annoying message from appearing and allow new users to register in the phpbb forum

The solution came natural and was a setting that had to be changed with the forum admin account, thus login as admin and look at the bottom of the page, below the text reading Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group you will notice a link with Administration Control Panel
just press there a whole bunch of menus will appear on the screen allowing you to do numerous things, however what you will have to do is go to
Board Settings -> Disable Board

and change the radio button there to say No

That's all now your forum will be ready to go and your users can freely register and if the server where the forum is installed has an already running mail server, they will receive an emails with a registration data concerning their new registrations in your new phpbb forum.
Cheers and Enjoy your new shiny phpbb Forum 🙂

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Posted in Linux, System Administration | 12 Comments »

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