[pkg-dhcp-devel] Bug#888209: Bug#888209: isc-dhcp-client: hammers DHCP server if it cannot write lease file

Axel Beckert abe at debian.org
Tue Jan 23 23:26:10 UTC 2018

Control: retitle -1 isc-dhcp-client: hammers DHCP server if it cannot write lease file (and might use up all available IP addresses in the LAN)
Control: severity -1 important

Hi Toni,

Toni Mueller wrote:
> I recently experienced a problem with dhclient issuing a ton of requests
> in rapid fire mode in an endless loop because the file system where it
> wanted to write its lease file, was mounted read-only. It got a new IP
> everytime and added them all to the interface.

Thanks for that bug report. Nice discovery.

I (not one of the isc-dhcp package maintainers, but lurking on their
list due to a general interest in DHCP) ran into that several times
now (with a single host using up all leases on my DHCP server!), but
only noticed it only due to no more leases being available, i.e. there
was nothing more left to debug.

So I assume it was caused by a temporarily full /var file system or
similar, which went away before I noticed that it also had these
hundreds of additional IPv4 addresses on my box as side effect.

Raising the severity to important as this might have a kind of DoS
effect on the local LAN (not the hammering but the using up of all
available IP addresses). ISC DHCP package maintainers: Feel free to
downgrade again if you disagree.

		Regards, Axel
 ,''`.  |  Axel Beckert <abe at debian.org>, https://people.debian.org/~abe/
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