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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.

Bad Google Indexing "Secure" Pages...

About a week ago I got a customer who started having their website appear in Google with HTTPS (the secure version of the site.) The pages are served securily, but it uses our website certificate so you get a big bad error saying that everything is broken and if you proceed you'll know what hell is like.

"This Connection is Untrusted" by FireFoxThe fact is that this customer never had a secure certificate. In other words, there is no reason for the site to have been referenced with HTTPS unless someone typed a link to their site and inadvertendly entered https://... instead of http://...

I checked a few of the pages where there ...

South Sudan top-level domain is .ss

Very recently, Sudan was split in the northern and southern part. The southern part has a new name: South Sudan. It is now official and the new ISO country code given to this new country is SS.

This means their country top-level domain name will be .ss.

Assuming they open their domain name to all world wide, this is going to be quite interesting! There are many words in the English language that end with .ss such as dre.ss, and stre.ss, and le.ss...

If you're in the domain name business, look out for those! If it works like other top-level domains, these will go really quick and make ...

MobileKey global settings

The MobileKey module comes with the following settings. These settings are found here:

Administer » Site configuration » MobileKey

Front Page Redirect

Since you generally give one URL to your users, your home page (called Front Page in Drupal), it can be practical to send Mobile phone users to a special URL so when they access your site they see a better adapted front page than the usual.

The settings accept a local path (i.e. mobile) or a full path (i.e. http://mobile.example.com/).

Note that this gives you a way to use the ThemeKey capability to change the theme of all ...

What Country is this Domain Name Extension from?

Domain Descriptions

Got a URL with a weird extension at the end (i.e. not a .com, .org, .info, .tv...) Wondering where that extension is from? Some, you may know because it is the usual country code, such as .de, .fr or .it. Others are harder to know because you probably did not learn the name of the some 276 countries of the world (know of .fm, .vc, .vg, .ws and .ng?)

One or two of the taxonomy columns are too wide

It happens that a column in your main display look too wide. Say you use three columns, one may be real large and two are the normal size (1/3rd of the screen.)

In general this happens because you have a URL in one of your description. (If the URL is in the title, I strongly advice that you move it to the description.) Then the description shows up as wide as that URL. Long URLs will have a real bad effect making the column much wider.

There are two ways to solve the problem:

  1. Create a tiny URL, although tiny URLs may still be too big, it may help
  2. Change the settings of the ...