[pkg-dhcp-devel] Bug#712503: isc-dhcp-server: DHCP server is still listening on random interfaces

[Rimvydas]

Package: isc-dhcp-server
Version: 4.3.5-3.1
Followup-For: Bug #712503

Dear Maintainer,

-- System Information:
Debian Release: 9.4
  APT prefers stable
  APT policy: (700, 'stable'), (650, 'testing'), (500, 'stable-updates')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-6-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Actually, there are two issues:

1) dhcpd is listening on random port (UDP) for all interfaces, no
   configuration option or CLI switch can fix with this situation.
2) moreover, dhcpd is listening for UDPv6 too, even if you include -4
   option for dhcpd (I have ipv6 disabled via sysctl)

$ cat /etc/default/isc-dhcp-server

INTERFACES="eth2"
OPTIONS="-4"

  PID TTY      STAT   TIME COMMAND
 7714 ?        Ss     0:00 /usr/sbin/dhcpd -4 -q -cf /etc/dhcp/dhcpd.conf eth2

$ netstat -tulp

udp        0      0 0.0.0.0:23961           0.0.0.0:*                           7714/dhcpd
udp6       0      0 :::64049                :::*                                7714/dhcpd