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[Thomas Morin <1623849@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

The ovs-ofctl ARP responder implementation (install_arp_responder) sets
the correct src/dst MAC addresses in the Ethernet header:

https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/drivers/openvswitch/agent/openflow/ovs_ofctl/br_tun.py#L197

https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/drivers/openvswitch/agent/common/constants.py#L110

--> 'move:NXM_OF_ETH_SRC[]->NXM_OF_ETH_DST[],mod_dl_src:%(mac)s,'

*However* the native Openflow/ryu install_arp_responder implementation
does not set these src/dst fields of the Ethernet header:

https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/drivers/openvswitch/agent/openflow/native/br_tun.py#L223


The result is that the forged ARP response is incorrect arp_responder=True and of_interface=native:

09:59:47.162196 fa:16:3e:ea:2e:9a > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Request who-has 192.168.10.1 tell 192.168.10.5, length 28
09:59:47.162426 fa:16:3e:ea:2e:9a > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Reply 192.168.10.1 is-at fa:16:5e:47:33:64, length 28

** Affects: neutron
     Importance: Undecided
         Status: New


** Tags: ovs

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https://bugs.launchpad.net/bugs/1623849

Title:
  openvswitch native agent, ARP responder response has wrong Eth headers

Status in neutron:
  New

Bug description:
  The ovs-ofctl ARP responder implementation (install_arp_responder)
  sets the correct src/dst MAC addresses in the Ethernet header:

  https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/drivers/openvswitch/agent/openflow/ovs_ofctl/br_tun.py#L197

  https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/drivers/openvswitch/agent/common/constants.py#L110

  --> 'move:NXM_OF_ETH_SRC[]->NXM_OF_ETH_DST[],mod_dl_src:%(mac)s,'

  *However* the native Openflow/ryu install_arp_responder implementation
  does not set these src/dst fields of the Ethernet header:

  https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/drivers/openvswitch/agent/openflow/native/br_tun.py#L223

  
  The result is that the forged ARP response is incorrect arp_responder=True and of_interface=native:

  09:59:47.162196 fa:16:3e:ea:2e:9a > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Request who-has 192.168.10.1 tell 192.168.10.5, length 28
  09:59:47.162426 fa:16:3e:ea:2e:9a > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Reply 192.168.10.1 is-at fa:16:5e:47:33:64, length 28

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