gitzone

About

gitzone is a git-based zone file management tool for BIND. Users can update their zones in a git repository then during a push the zone files are checked, updated & reloaded from git receive hooks. If there’s an error in a file being pushed then the push is rejected, thus only correct files are stored on the server.

gitzone-shell is a wrapper for git-shell that restricts the user to the zones repository and provides some additional commands for dynamic DNS updates & SSH key management.

Installation

• set PREFIX in Makefile and make sure the paths in the hooks are correct, then

  # make install
      

• edit the settings in gitzone-shell
• create users with ssh access and set their shell to gitzone-shell
• create a zones repo for each user and set receive.denyCurrentBranch to ignore, this allows pushing to a checked out repository. The checked out files are used for incrementing serials and validating the zones with named-checkzone.

  # cd ~$user
  # git init zones
  # ln -s zones $username  # needed for named-checkzone
  # cd zones
  # git config receive.denyCurrentBranch ignore
  # cd hooks
  # ln -s /usr/lib/gitzone/hooks/pre-receive
  # ln -s /usr/lib/gitzone/hooks/post-receive
      

• create a .gitconfig for the user that contains user name & user email (used for auto increment commits)
• edit the settings in gitzone.conf
• create a directory for each user in $zone_dir and chown it to the user, this will contain a clone of the user’s repository, the zone files here should be included in named.conf.

  # cd $zone_dir
  # mkdir $user
  # chown $user:$group $user
      

• edit named.conf and set directory in options to $zone_dir, this is needed to make relative file names work in $INCLUDE:

  options {
    directory "/var/named";
    // ...
  }
      

Usage

Git repository

To make changes to the zones you need to clone the git repository, edit the files, commit the changes and finally push the changes to the server. If you use the auto increment feature you also need to pull after a push as the receive hooks on the server make commits to the repository during a push.

% git clone ns.example.net:zones
% cd zones
% # edit files
% git commmit
% git push origin && git pull

SSH commands

The following SSH commands are provided by gitzone-shell:

• update-record <filename> <record>: updates the IP address of the first matched record in the given file to the SSH client’s IP address.

  % ssh ns.example.net update-record example.net somehost IN A
      

• SSH key management commands, to use these touch .ssh/authorized_keys_edit_enabled in the users’ home directories.
  • list-keys: list added ssh keys

    % ssh ns.example.net list-keys
            

  • add-key: add a new ssh key

    % ssh ns.example.net add-key `cat id_rsa.pub`
            

    or only allow one specific command:

    % ssh ns.example.net add-key 'command="update-record example.net somehost IN A"' `cat id_rsa.pub`
            

  • del-key: delete an ssh key from the config

    % ssh ns.example.net del-key user@somewhere
            

Dynamic DNS

In order to do automatic dynamic DNS updates, create an SSH key without a password and use the add-key command to add it with a command= parameter which has an update-record command in it, see the example in the previous section. This way the host doing the updates does not have access to the git repository as it is restricted to the specified command only. Then all you have to do to update your IP is:

% ssh ns.example.net

Run this command whenever the IP changes or the interface comes up.

Debian, Ubuntu

On Debian-like systems you can use a post-up command in /etc/network/interfaces.

Gentoo

On Gentoo you can put a postup() function in /etc/conf.d/net.

Zone files

There are a few keywords you can use in the zone files:

• ;AUTO_INCREMENT after a serial number to automatically increment it during a push. If the number is 10 digits and starts with 20 it’s treated as a date. e.g.:

  example.net.  IN  SOA  ns1.example.net. hostmaster.example.net. (
                         2011013101  ;AUTO_INCREMENT
                         1d 2h 4w 2d )
      

• $INCLUDE can be used to include other files from the repository, the file names should be prefixed with the user name
• ;INCLUDED_BY on the first line of a file indicates what other files include this file. When this file is committed & pushed all the other files listed after ;INCLUDED_BY are reloaded as well.

  E.g. if you have the following files in the repository then a change in example-common would result in the reload of both example.net & example.org:

  • example.net:

    ...
    $INCLUDE username/example-common example.net.
            

  • example.org:

    ...
    $INCLUDE username/example-common example.org.
            

  • example-common:

    ;INCLUDED_BY example.net example.org
    ...