Using OpenNetAdmin for network documentation

It’s probably a familiar situation for every sysadmin… at some stage, your network grows to be too large for your trusty spreadsheet to keep track of. In enterprise networks this is especially true, where the number of servers can easily be in the hundreds.

While looking for a good, open source solution to this problem, I ran across OpenNetAdmin:

http://opennetadmin.com/

OpenNetAdmin is based on the usual open-source LAMP stack, making it easy to setup, and to customise. Some advantages using this solution would be:

– No need to synchronise spreadsheets/documents between team members

– Centralised components, making it easier to backup

– When adding a host, the program automatically determines the subnet, etc

A couple of tips learned while using this program:

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Adding NAT IP addresses

One of the new features in the latest release of OpenNetAdmin is the ability to document NAT addresses. How to do this is not very well documented. To add a NAT address:

1. Add the appropriate subnet (Menu > Edit > Add Subnet)

2. Add the appropriate host to the subnet created in step 1 (Menu > Edit > Add Host)

3. Add an interface to the host

The above option will ask you to enter the private IP of the server.

4. Once done, to the right of your newly-created entry, click the “+” icon and select the “Add NAT IP” option

This will ask you to enter the public IP that maps to this interface, leaving you with a mapping such as:

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Custom Attributes

Custom attributes are really useful. They allow you to document any attribute you deem useful. For example, while OpenNetAdmin does allow documenting VLANs, we found it clunky when trying to search for hosts and servers belonging to a certain VLAN ID. As a workaround, you may use custom attributes.

1. Make sure you are using the “admin” user, and define a host/server

2. Define a new custom attribute (Menu > admin > manage custom attribute types > add custom attribute type)

3. Add a custom attribute named “VLAN”

4. Define a new host or navigate to a pre-existing host. Hit the “add custom attribute” and choose the newly-selected attribute, entering in the appropriate value.

It should now be possible to search for hosts having this attribute. So in our case we can search for hosts in a particular vlan ID (Hosts > Search > Hosts > Custom Attribute)

Some other ideas for custom attributes:

• HBA mappings – use to keep track of host WWNs
• Guests – used on VM / KVM / XEN servers to keep track of guests hosted on the server
• Physcial – used on virtual guests to keep track of which physical server it is installed on

All in all, a very useful tool, check out the rest of the features of the tool on:

http://opennetadmin.com/docs/