I am experiencing a strange behaviour, and this might be connected to
the bug #595190 (isc-dhcp-client: goes into an infinite loop if server
only answers on broadcast).
I am trying to debug two DHCP servers (one is on a Windows Server 2012
R2, and the other one is dnsmasq on Ubuntu 22.04).
*To check them both, I am using the option '-s <address>", but this does
not work correctly.*
* dhclient sends a DHCPDISCOVER, and as the option suggests, it does
not send this as a broadcast, but as a unicast to the server given
in the option.
* Neither DHCP server, however, answers this with a DHCPOFFER, but
both of them send a DHCPACK.
* So, it seems as if dhclient assumes to have sent a DHCPDISCOVER and
thus waits for a DHCPOFFER - whereas the servers seem to interpret
the package as a DHCPREQUEST and answer with DHCPACK.
* As this behaviour is identical on both DHCP servers, I dare to
assume that this is an error in the package sent by dhclient.
* (Moreover, although I deleted the file /var/lib/dhcp/dhcp.leases,
the dhclient somehow seems to remember its former lease address and
inserts it into the DHCPDISCOVER package. Is that correct?)
* And worse, if I do not delete the old lease file, dhclient sends a
DHCPREQUEST for its former address - which will can be acknowledged
if the request is for an address issued from server A, and the
request goes to server B... (but this might be by design)
I observe the behavior with dhclient
* sc-dhclient-4.4.3 on Linux Debian 12
* isc-dhclient-4.4.1 on Linux Mint 20.3 Una
* sc-dhclient-4.4.1 on LinuxUbuntu 20.04.5
Best regards,
--
Ralf „Pi“ Pichocki.
Bahnhofstraße 190
45770 Marl-Sinsen
Germany
+49 2365 9559945 (Tel)
+46 382 650999 (Tel)
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ralf.pichocki@gmx.de <mailto:ralf.pichocki@gmx.de>(Mail)