[Bug 1606051] Re: dhclient fails to get address after latest patches

[Alberto Salvia Novella]

** Changed in: isc-dhcp (Ubuntu)
   Importance: Undecided => High

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Title:
  dhclient fails to get address after latest patches

Status in isc-dhcp package in Ubuntu:
  Confirmed

Bug description:
  From ASkUbuntu entry http://askubuntu.com/questions/801136/recent-
  patches-broke-dhclient/802390

  Running 16.04.01 LTS recently upgraded from 15.10. System is a home firewall with enp1s0 as LAN interface statically assigned and enp2s0 is WAN interface using DHCP, connected to modem.
  Ran apt-get upgrade and on reboot enp2s0 had no address. running ifdown enp2s0 and then ifup enp2s0 gave me

  root at sam:~# ifup enp2s0
  Internet Systems Consortium DHCP Client 4.3.3
  Copyright 2004-2015 Internet Systems Consortium.
  All rights reserved.
  For info, please visit https://www.isc.org/software/dhcp/

  Listening on LPF/enp2s0/d0:50:99:21:80:f8
  Sending on   LPF/enp2s0/d0:50:99:21:80:f8
  Sending on   Socket/fallback
  DHCPDISCOVER on enp2s0 to 255.255.255.255 port 67 interval 3 (xid=0xd998571a)
  send_packet: Network is down
  dhclient.c:2098: Failed to send 300 byte long packet over enp2s0 interface.
  receive_packet failed on enp2s0: Network is down
  DHCPDISCOVER on enp2s0 to 255.255.255.255 port 67 interval 5 (xid=0xd998571a)
  send_packet: Network is down
  Running ifconfig enp2s0 up and dhclient enp2s0 gave similar results, but eventually /var/log/syslog showed a dhclient ipv4 lease being obtained - but the enp2s0 had only an IPv6 address, which appears to have come from avahi-daemon.

  I then manually configured the enp2s0 interface with ifconfig enp2s0
  xxx.xxx.xxx.xxx netmask 255.255.248.0 and put in a default route based
  on the lease info in dhclient.leases and I'm back online. But if I
  reboot or try to get dhclient to work, I continue to get the network
  is down errors.

  apparmor is disabled, so that's not it. iptables is set to allow all
  DHCP traffic (67/udp and 68/udp) and all RELATED,ESTABLISHED traffic
  from enp2s0.

  enp2s0 and enp2s0 are the same hardware.

  root at sam:~# lshw -class network
    *-network
         description: Ethernet interface
     product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
     vendor: Realtek Semiconductor Co., Ltd.
     physical id: 0
     bus info: pci at 0000:01:00.0
     logical name: enp1s0
     version: 01
     serial: 04:8d:38:5d:20:17
     size: 100Mbit/s
     capacity: 1Gbit/s
     width: 64 bits
     clock: 33MHz
     capabilities: pm vpd msi pciexpress bus_master cap_list rom ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
     configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full ip=yyy.yyy.yyy.yyy latency=0 link=yes multicast=yes port=MII speed=100Mbit/s
     resources: irq:38 ioport:e000(size=256) memory:ffa00000-ffa00fff memory:ffa20000-ffa3ffff
    *-network
     description: Ethernet interface
     product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
     vendor: Realtek Semiconductor Co., Ltd.
     physical id: 0
     bus info: pci at 0000:02:00.0
     logical name: enp2s0
     version: 11
     serial: d0:50:99:21:80:f8
     size: 1Gbit/s
     capacity: 1Gbit/s
     width: 64 bits
     clock: 33MHz
     capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
     configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl8168g-2_0.0.1 02/06/13 ip=xxx.xxx.xxx.xxx latency=0 link=yes multicast=yes port=MII speed=1Gbit/s
     resources: irq:40 ioport:d000(size=256) memory:ff900000-ff900fff memory:d0800000-d0803fff
  Ideas? remember, this happened right after patching.

  networking network-manager dhclient

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: isc-dhcp-client 4.3.3-5ubuntu12.1
  ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
  Uname: Linux 4.4.0-31-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2.1
  Architecture: amd64
  Date: Sun Jul 24 15:33:19 2016
  InstallationDate: Installed on 2016-03-01 (145 days ago)
  InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: isc-dhcp
  UpgradeStatus: Upgraded to xenial on 2016-06-22 (32 days ago)
  mtime.conffile..etc.dhcp.debug: 2016-06-28T18:13:33.371977

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