IP Manager

The IP Manager (ipmgr) is a tool used to manage domain name definitions in the BIND9 DNS system.

Testing Zone Transfers

The primary is expected to send its zones to the secondaries. This generally works well, but once in a while a BIND9 server may stop sending the data for all sorts of reasons. To manually test that a zone transfer works, use dig like so:

$ ssh my.secondary.server
$ dig AXFR @primary.server one.of.my.domains

The dig command will show the transferred zone results or an error message such as:

$ dig axfr @ns1.m2osw.com best-gamblers.games

; <<>> DiG 9.18.12-0ubuntu0.22.04.1-Ubuntu <<>> axfr @ns1.m2osw.com best-gamblers.games
; (1 server found)
;; global options: +cmd
; Transfer failed.

The transfer clearly fails in this case. Unfortunately, we do not get much information about why it failed such as:

• Primary BIND does not want to transfer (transfer was forbidden, somehow).
• Primary sends data without the AA flag (non-authoritative).
• Your firewall is in the way (TCP port 53 must be open on primary).
• Your Internet service provider tempers with your packets.

Dynamic IPs with BIND9 Breaks

I've experience breakage with BIND9 when sending it too many updates in a row. It looks like it will never delete (or at least recycle) the journals and as a result the files grow until the whole thing crashes. After that, the corresponding zone fails to load even on a full restart cycle.

When the IP Manager is asked to restart the BIND9 service, it will also make sure to delete the .jnl files. This way, we start fresh and BIND9 work as expected.

Note: This BIND9 bug is still present in Ubuntu 20.04.

Changing BIND9 Settings

A while back, I had a need to edit BIND9 settings in my installation scripts. The main issue with BIND9 is that you can't easily override settings by creating a file such as:

bind9.d/50-named.conf

Since that is not supported, you are left with having to edit the existing .conf files manually. For me to me able to make such edits in installation scripts, I decided to create a tool: dns-options. This tool is now part of the IP Manager project and some bugs from the old version were fixed (it still is very bogus, some options just can't be automatically edited just yet).

Documentation

See the conf/README-zones.md for details about the configuration of ipmgr. There are actually several files defined like so:

• conf/README.md

  Defines how to safely make changes to the ipmgr.conf file without the risk of having your changes smashed when upgrading ipmgr.

• conf/README-ipmgr.md

  Defines what goes in the /etc/bind9/zones directory. It gets installed in that directory.

• conf/README-static-zones.md

  IP Manager supports two types of zones: dynamic and static. Static zones are generally installed by packages and the only way to edit them is to update that package and then apply an update on your system.

  These zones are found under /usr/share/ipmgr/zones/....

• conf/README-zones.md

  When a tool generates an ipmgr .ini file with a zone definition, it can save that definition under /var/lib/ipmgr/zones/.... These files are considered dynamic.

  This README file also includes details on how to write the .ini file with each parameter defined, how to use it, some examples, etc.

  Here is an example of configuration of a zone and as you can see, we use a simple .ini format: <name>=<value> and separate sections with [<section>]. A section is used to create and define a subdomain.

  domain=example.com
  [email protected]
  ips=10.0.0.1
  mail=mail
  ttl=60m
  refresh=3h
  retry=3m
  expire=2w
  minimum_cache_failures=5m
  dynamic=true
  nameservers="ns1.example.com ns2.example.com"
  
  [server]
  sub_domains=server
  
  [websites]
  sub_domains=${website_subdomains}
  ttl=5m
  cname=server
  
  [api]
  sub_domain=rest api graphql
  ips=${api_ip}
  
  [mail]
  sub_domains="mail"
  ips=10.0.2.1
  ttl=4w
  mail_priority=10
  mail_key=mail.example.com.key
  key_ttl=30m
  auth_server=true
  
  [info]
  sub_domains=info
  txt="description=this domain is the best"
  

• BIND9 Further Reading

  The IP Manager uses BIND9 to do the actual DNS serving part. You can find the BIND9 document online. The IP Manager installs a few configuration files and generates the necessary commands to transform ipmgr settings found in .ini files to .zone and .conf file to add your domain names to the server. It also automatically restart BIND9 for you when changes were applied.

License

The ipmgr project is covered by the GNU GENERAL PUBLIC LICENSE Version 3 or higher.

See the LICENSE.txt file for details. If you can't find the LICENCE.txt file, check out the https://www.gnu.org/licenses/ web page.

Logo

I created the Logo using a font created by Film Himmel - Jens R. Ziehn.

It is limited to uppercase A to Z and arabic digits 0 to 9.

Bugs

Submit bug reports and patches on github.

This file is part of the snapcpp project.