Replacing deprecated isc-dhcp-client (dhclient)

[MichaIng]

Discussed in https://github.com/MichaIng/DietPi/discussions/7796

^{Originally posted by Snurring November 1, 2025} Hi,

The dhcp client currently in use in dietpi has been deprecated for years. Do you plan to replace it in future releases?

[MichaIng]

Background:

• Client deprecation: https://www.isc.org/blogs/dhcp-client-relay-eom/
• Server deprecation: https://www.isc.org/blogs/isc-dhcp-eol/

Here the DHCP clients supported by ifupdown in Debian Bookworm, which did not change in Trixie or Forky so far: https://manpages.debian.org/bookworm/ifupdown/interfaces.5.en.html#The_dhcp_Method

• udhcpc depends on busybox, but both is tiny.

• dhcpcd is well known, and can be installed without the systemd/init.d services, to avoid conflicts: https://packages.debian.org/dhcpcd-base Needs testing, e.g. it must run with --nohook to avoid unintentional interference. Better to be implemented only after we dropped Bullseye support with first release next year. The older dhcpcd5 source does not provide a standalone executable package without systemd unit, and the main package name differs as well.

For the same reason, the isc-dhcp-server (dhcpd) for the WiFi hotspot should be replaced.

• A known alternative, which includes DNS where needed, is dnsmasq. However, I am not sure whether DNS can be disabled completely, which is mandatory for us to maintain compatibility with Unbound, Pi-hole etc.
• ISC themselves provide their successor Kea, which provides a lot of features including database server backends and all such. But means large size and high complexity, not exactly a default solution I'd usually pick for DietPi.
• Not so well known, but there is also CoreDHCP: https://packages.debian.org/coredhcp-server
• Oh wait, as I was mentioning udhcpc as client, there is the respective server as well: udhcpd Quite an idea to use those two, as they seem to be very simple minimal implementations. Little side effect is that initramfs-tools by default uses busybox instead of klibc utils, if installed. AFAIK it adds some more features to the initramfs console, but might also raise its size a bit.