DHCPDISCOVER loop

Installing and Using OpenWrt
1

My wifi was acting unreliably so I looked at my router log and was surprised to see this loopy pattern:

Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) f0:c9:d1:e5:f1:71
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.198 f0:c9:d1:e5:f1:71
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.221 00:62:6e:e9:b9:0d
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.221 00:62:6e:e9:b9:0d
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPREQUEST(br-lan) 192.168.2.65 f8:b1:56:d7:72:9b
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPACK(br-lan) 192.168.2.65 f8:b1:56:d7:72:9b optiplex
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.194 00:62:6e:e9:ba:37
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.194 00:62:6e:e9:ba:37
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) bc:0f:2b:aa:9b:3b
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.200 bc:0f:2b:aa:9b:3b
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.221 00:62:6e:e9:b9:0d
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.221 00:62:6e:e9:b9:0d
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 169.254.69.214 5c:ea:1d:02:34:45
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.209 5c:ea:1d:02:34:45
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.194 00:62:6e:e9:ba:37
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.194 00:62:6e:e9:ba:37
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.221 00:62:6e:e9:b9:0d
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.221 00:62:6e:e9:b9:0d
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.194 00:62:6e:e9:ba:37
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.194 00:62:6e:e9:ba:37
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.221 00:62:6e:e9:b9:0d
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.221 00:62:6e:e9:b9:0d
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.194 00:62:6e:e9:ba:37
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.194 00:62:6e:e9:ba:37
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPDISCOVER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPOFFER(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPREQUEST(br-lan) 192.168.2.221 00:62:6e:e9:b9:0d
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPACK(br-lan) 192.168.2.221 00:62:6e:e9:b9:0d foscam-living-eth
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPREQUEST(br-lan) 192.168.2.194 00:62:6e:e9:ba:37
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPACK(br-lan) 192.168.2.194 00:62:6e:e9:ba:37 foscam-sbr-eth
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPREQUEST(br-lan) 192.168.2.196 00:62:6e:d8:8c:62
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPACK(br-lan) 192.168.2.196 00:62:6e:d8:8c:62 foscam-kitchen-eth
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPREQUEST(br-lan) 192.168.2.193 00:62:6e:e9:95:aa
Tue Sep  1 14:11:50 2020 daemon.info dnsmasq-dhcp[2991]: DHCPACK(br-lan) 192.168.2.193 00:62:6e:e9:95:aa foscam-mbr-eth

Any idea what could be going wrong? is the DHCPDISCOVER packet in a forwarding loop? Unless a device is spoofing MAC, the client with MAC address (00:62:6e:e9:95:aa) is an IP camera (Foscam) connected via ethernet to the router via 3 nested switches. I think the switches are in a tree structure with no cycles.

2

Try to connect the camera directly on the router or connect another device where the camera is to rule out issues with the switches or with the camera.

2 Likes
3

Hummm...Make sure you enable Spanning Tree Protocol.