Bug#932769: [moreinfo] DoS via DHCP request

[Tomas Pospisek <tpo_deb@sourcepole.ch>]

Package: general
Followup-For: Bug #932769

Could you privide a recipe on how to reproduce this? There's a lot of
very special setup below, that someone wwould need large amounts of time
to reporoduce I feel.

Is it possible to reduce the problem to something easily demonstratable?

This seems to be an important issue to me.

I think the problem here *might* be a kernel problem? Re-assign this to
kernel package?

When you say that it DoS'es the server then what does "top" say? What is
being DoS'ed? Is it the CPU?
*t

It would be truly cool, if you could provide more infos.
*t

> To: Debian Bug Tracking System <submit@bugs.debian.org>
> Subject: general: DHCP request bug when storage lost
> Date: Mon, 22 Jul 2019 14:48:00 -0600
> 
> Package: general
> Severity: important
> Tags: l10n
> 
> Dear Maintainer,
> 
> While doing unrelated storage testing for our VMware integrated product, we purposefully recreated
> a storage outage by removing the iSCSI initiators from the backing array hosting the vmdk disk 
> images for the virtual machine.
> 
> Upon removal of uplinks to storage, the VM goes into a R/O file system state after 5-10 minutes.
> When storage initiators are brought back up and the LUNs are rescanned, the VM begins to 
> rapidly request DHCP leases from an ISC DHCP server.  This DoS's the server in a way due
> to the number of DHCPDECLINE errors, and the interface attempts to take and discard IP's in a
> rapid fashion. 
> 
> This only seems to appear on this distribution, and I can't replicate the behavior on Debian 9
> or in a desktop environment.
> 
> 
> 
> -- System Information:
> Debian Release: 10.0
>   APT prefers stable
>   APT policy: (500, 'stable')
> Architecture: amd64 (x86_64)
> 
> Kernel: Linux 4.19.0-5-amd64 (SMP w/1 CPU core)
> Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
> Shell: /bin/sh linked to /usr/bin/dash
> Init: systemd (via /run/systemd/system)
> LSM: AppArmor: enabled





-- System Information:
Debian Release: 10.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.19.0-5-amd64 (SMP w/8 CPU cores)
Locale: LANG=de_CH.utf8, LC_CTYPE=de_CH.utf8 (charmap=UTF-8), LANGUAGE=de_CH:de (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled