https://samy.pl/poisontap/

This is a variation on an ancient "gem" by a DSL Modem vendor
where the router pretends to be the entire internet by spoofing
arp so that it captures all traffic.

The best way to deal with this is to set an upper limit on the
size of acceptable netmask in /etc/default/isc-dhcp-client and
verify it in a hook (which can be debian specific).

This way dhcp reply of 0.0.0.0/0 or anything larger than a class
A will raise a security alert instead of blindly exposing the
machine to a spoofing attack.

Hi,

When an attacker can attach devices to your machine, there are lots of
possible ways they can mess with it. Filtering certain dhcp replies will not
change this that much (they could remove the network cable, if there is a
switch to disable wifi they could use that, etc), so I'm lowering the severity
of this bug.

Cheers,

Ivo

Dear submitter,

as the package isc-dhcp has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1143544

The version of this package that was in Debian prior to this removal
can still be found using https://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)