Exploring dhcpy6d, a DHCP server for IPv6 networks

Not Just Addresses

Test Results and Conclusions

In theory, IPv6 network administrators can manage without a DHCP server; however, in practice, with larger networks (and most IPv6 networks usually are large) the additional parameters transmitted through DHCP are important to the configuration.

Dhcpy6d left a mixed impression. The idea of ignoring the RFC, prompted by practical considerations, and allowing mapping via the MAC address doesn't appear far off the mark at first. After all, the way the DHCPv6 service calculates the DUIDs differs from implementation to implementation anyway. But what I really felt was missing was the ability to assign an address based on the network segment the client is put in. DHCP relay agents are also used with IPv6 in larger networks, and in addition to the MAC address, the DHCPv6 server needs to know which segment the client resides in so the correct parameters are available for the network.

Dhcpy6d relies on individual client definitions and classes. Unknown clients on networks always end up in the default class; they are therefore allocated incorrect addresses and, just as an example, maybe the wrong DNS server. You can only manage this situation by sorting the entries manually.

Henri Wahl, the software's author, provides good support for user questions, and a steady stream of questions helps the developers learn what is or isn't working in the real world. Our test team detected a few logical loopholes using a different approach to the configuration, and our research prompted a number of Git commits.

Infos

DHCPv6 RFC: https://tools.ietf.org/html/rfc3315
Dibbler: http://klub.com.pl/dhcpv6/
ISC DHCP and DHCPv6: https://www.isc.org/downloads/dhcp/
WIDE-DHCPv6: http://sourceforge.net/projects/wide-dhcpv6/
NDP: https://en.wikipedia.org/wiki/Neighbor_Discovery_Protocol
dhcpy6d repository: https://github.com/HenriWahl/dhcpy6d
dhcpy6d: https://dhcpy6d.ifw-dresden.de
EUI-64: http://standards.ieee.org/develop/regauth/tut/eui64.pdf
radvd: http://www.litech.org/radvd/

The Author

Konstantin Agouros works at Xantaro, Germany, as a solutions architect focusing on network, cloud security, and automation. His book DNS/DHCP was published by Open Source Press.

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