Bug 35928 – Do not configure IPv4 link local address as dhcp lease

Bug 35928 - Do not configure IPv4 link local address as dhcp lease


Summary:	Do not configure IPv4 link local address as dhcp lease

Status:	RESOLVED WONTFIX

Product:	UCS
Classification:	Unclassified
Component:	Network
Version:	UCS 4.2
Hardware:	Other Linux

Importance:	P5 normal (vote)
Target Milestone:	UCS 4.x
Assigned To:	UCS maintainers
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Reported:	2014-09-15 12:14 CEST by Erik Damrose
Modified:	2020-07-03 20:52 CEST (History)
CC List:	2 users (show)

See Also:	26416
What kind of report is it?:	Bug Report
What type of bug is this?:	2: Improvement: Would be a product improvement
Who will be affected by this bug?:	1: Will affect a very few installed domains
How will those affected feel about the bug?:	1: Nuisance – not a big deal but noticeable
User Pain:	0.011
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Description Erik Damrose

2014-09-15 12:14:29 CEST

When no IP address can be configured during an UCS boot, dhclient reads its config file dhclient.conf and checks for a previous lease that is still valid.

During UCS boot we write a link-local address as a previous lease to the dhclient.conf, which is read by dhclient which subsequently configures that address for eth0 if no DHCPOFFER is received. The problem here is, that we write a link local address, which could never have been obtained via dhcp.

The following problem may then occur: dhclient configures the link local address and broadcasts this fact to all listening dhcp servers. We had a dnsmasq running on another dev-machine, which promptly sends a DHCPNAK back. Thus, no IPv4 address is configured for eth0. In my case, the univention-system-setup/umc-web-server/umc-server/apache proxy-connection setup failed, and system setup does not load.

Solution: Do not configure the link local address via dhclient.conf, but by other means

Comment 1 Philipp Hahn

2017-04-21 14:43:31 CEST

You can disable the fallback behavior by UCRV dhclient/linklocal/fallback=0

@Stefan: why do we need the fallback link-local address at all?

Comment 2 Ingo Steuwer

2020-07-03 20:52:16 CEST

This issue has been filed against UCS 4.2.

UCS 4.2 is out of maintenance and many UCS components have changed in later releases. Thus, this issue is now being closed.

If this issue still occurs in newer UCS versions, please use "Clone this bug" or reopen it and update the UCS version. In this case please provide detailed information on how this issue is affecting you.