I've configured my Raspberry Pi for static IP. My /etc/network/interfaces looks like this:
auto lo
iface lo inet loopback
auto eth0
allow-hotplug eth0
iface eth0 inet static
address 192.168.1.2
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1
Yet for some strange reason, every time I reboot my Pi or my router, my Pi gets the requested IP (192.168.1.2) but ALSO a DHCP address (192.168.1.18). So my Pi has two addresses.
Of course, this isn't necessarily a problem, I just think it's strange. Am I doing something wrong? Or not enough? My router is almost completely locked down for management, but I can enter static IPs for devices - is this necessary, if I configure the Pi to do it?
The dynamic address isn't apparent in ifconfig:
eth0 Link encap:Ethernet HWaddr b8:27:eb:5d:87:71
inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:236957 errors:0 dropped:34 overruns:0 frame:0
TX packets:260738 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:35215632 (33.5 MiB) TX bytes:70023369 (66.7 MiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:27258 errors:0 dropped:0 overruns:0 frame:0
TX packets:27258 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:3397312 (3.2 MiB) TX bytes:3397312 (3.2 MiB)
yet I can ping, ssh and everything on .18 as well.
Since you can add multiple IP addresses to the interface eth0 as noted above, I believe the solution to your problem is to remove the auto eth0 line from your /etc/network/interfaces file.