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Docker, an advanced chroot utility


Chasm—just like a Docker creates a chasm between two sets of software

SECURITY WARNING

Before installing Docker and containers with services on your Linux system, make sure to read and understand the risks as mentioned on this Docker and iptables page. Especially, Docker will make all your containers visible to the entire world through your Internet connection. This is great if you want to indeed share that service with the rest of the world, it's very dangerous if you are working on that container service since it could have security issues that need patching and such. Docker documents a way to prevent that behavior by adding the following rule to your firewall:

iptables -I DOCKER-USER -i eth0 ! -s 192.168.1.0/24 -j DROP

This means that unless the IP address matches 192.168.1.0/24, the access is refused. The `eth0` interface name should be replaced with the interface name you use as the external ethernet connection. During development, you should always have such a rule.

That has not worked at all for me because my local network includes many other computers on my LAN and this rule blocks them all. So really not a useful idea.

Instead, I created my own entries based on some other characteristics. That includes the following lines in my firewall file:

*filter
:DOCKER-USER - [0:0]

-A DOCKER-USER -j early_forward
-A DOCKER-USER -i eno1 -p tcp -m conntrack --ctorigdstport 80 --ctdir ORIGINAL -j DROP
-A DOCKER-USER -i eno1 -p tcp -m conntrack --ctorigdstport 8080 --ctdir ORIGINAL -j DROP
-A DOCKER-USER -i eno1 -p tcp -m conntrack --ctorigdstport 8081 --ctdir ORIGINAL -j DROP

My early_forward allows my LAN to continue to work. These are my firewall rules that allow my LAN computers to have their traffic forwarded as expected.

Then I have three rules that block port 80, 8080, and 8081 from Docker.

Docker will add new rules that will appear after (albeit not within the DOCKER-USER list) and will open ports for whatever necessary service you install in your Dockers.

Note that the only ports you have to block are ports that Docker will share and that you have otherwise open on your main server. If Docker opens port 5000 and your firewall does not allow connections to port 5000 from the outside, then you're already safe. On my end I have Apache running so as a result I block quite usual HTTP ports from Docker.

Docker

As we are helping various customers, we encounter new technologies.

In the old days, we used chroot to create a separate environment where you could have your own installation and prevent the software from within that environment access to everything on your computer. This is particularly useful for publicly facing services liek Apache, Bind, etc.

Help with version 0.1.7 of Zipios (CVE-2019-13453)

Here is yet another example of why opensource is a really good way of getting things fixed.

Assuming you have a project that is getting used by many, you are likely to see people post issues about bugs and possible enhancements. Your software is even very likely to get improved on its own by enthousiast users. On Github, for example, it is very easy to fork a project (make a copy) and then work on your version of the software. You can then offer a fix to the main authors of the project with a near one to one copy of the project.

In our case, a security professional, Mike Salvatore, was asked ...

Best C++ Books

Once in a while someone will ask me which book is best to start learning programming. The fact is that I do not know because I'm already an advanced programmer and it's rather difficult for me to get back to the basics (it feels like a waste of my time, sorry...)

That being said, at Made to Order Software, we've mainly been a C++ shop. We also do a lot of C, PHP, JavaScript and touch many other languages as required by the tasks we perform (bash, cmake, perl, C#, Java, etc.)

That being said, I wanted to underline some of the best C++ books available today. Especially, in the last ...

PHP e-Fax requires valid SSL certificates (failed with code 1)

As e-Fax is updating their systems further to be compliant with various security systems, some new problems may arise on your servers.

The main one is an SSL error that is quite unclear.

Warning: stream_socket_client(): SSL operation failed with code 1. OpenSSL Error messages: error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed in /path-to-php-efax/http_request.php on line 294

As we can see, the error mentions a server certificate function and says it could not verify a certificate.

If your server is not 100% up to date with newest SSL versions or your web ...

Upgrade to PHP 5.3.3 or newer because of security issue

If you are responsible for a Debian or Ubuntu server and run PHP on it, make sure to run the following command to fix several security issues found in PHP:

sudo apt-get install php5-suhosin

This will make the necessary and your PHP version (security wise) will look like you have PHP 5.3.3.

What I found quite annoying in regard to this issue is the fact that it was very difficult to find a mention of this upgrade. All I could find in large number were people saying that you'd have to get an upgrade using the source code of PHP. Somehow, I did not feel like upgrading PHP from ...

Protected Node Installation

The basics of the Protected Node installation are easy:

  1. Get one of the tarball from Drupal.org
  2. Extract the files under sites/all/modules or some other modules folder
  3. Go to Administer » Site building » Modules and install the module (package Access)
  4. As the administrator (UID = 1) you are done.

Once you have installed the module, you probably want to change the permissions. Permissions allow your users to access the Protected Node functionality based on their roles. Please, see the point about Permissions for more information about those.

Now, you're ready ...

jsMath Security Issue

Security Issue

A security issue was found in all versions of jsMath before 2.x-dev for Drupal 6.x of Jul 29, 2010.

You may still securely use older versions of jsMath on private websites and websites were you are the only user (as in, the only one who can log in.)

The Drupal Security Advisory issue is here: https://www.drupal.org/node/854402

Other Problem

There is another problem: jsMath offers a JavaScript function that parses entire web pages (although there are ways to circumvent that problem, the module does not currently make use of those.) The jsMath Drupal module uses the ...

SimpleMenu Custom Theme

Introduction

The newer versions of SimpleMenu allows for an easy way of adding custom themes.

There are two main ways to add new SimpleMenu themes:

1. In the simplemenu themes folder;

2. In your theme folder.

SimpleMenu themes folder

CSS

If you look under the simplemenu folder, you will see a sub-folder named themes. You can place your own specialized themes in that folder to make them available system-wide (i.e. if you are using many themes or use one Drupal installation for many websites.) In other words, this folder is viewed as a global theme folder.

The themes folder ...

Table of Contents tags and parameters

Syntax

Supported Tags

The module supports 3 tags that all generate a Table of Contents.

The most popular is now [toc] since it is easy to type and works in WYSIWYG editors.

Handling of Pop-up Windows by SimpleMenu

Feature

By default, SimpleMenu is not shown on pop-up windows. There is a flag in the SimpleMenu settings that can be unchecked to avoid this side effect. The pop-up capability is often detected when you open a new tab from the current window. It will depend on the browser and the link being clicked1.

Quick Fix

When the menu is only used by the administrators, it is possible to simply open a new tab and copy and paste the URL from the existing window with the missing menu to the ...

  • 1. We are trying to ameliorate the code, but it is not easy to make it work properly 100% of the time.