Host-only VirtualBox vboxnet1 IP belongs to host - virtualbox

Question

I'm trying to connect to a server running on a guest OS in VirtualBox. VirtualBox is configured to assign a static IP to the guest. However I'm pretty sure that the IP it assigns actually belongs to the host. If I have an nginx server running on the host then requests to the vboxnet1 IP are intercepted by the host serve and never reach the guest.
Both the host and guest are Debian.
Also, I get the same result with and without the VirtualBox DHCP server enabled.
Here's the VirtualBox network settings (can't embed images with <10 rep...sigh):
And the VM network settings:
I've also tried with different IP addresses for the host, no change.
ifconfig on host:
$ ifconfig
eth0 Link encap:Ethernet HWaddr 00:90:f5:e8:b0:e0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:183363 errors:0 dropped:0 overruns:0 frame:0
TX packets:183363 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:70022881 (70.0 MB) TX bytes:70022881 (70.0 MB)
vboxnet1 Link encap:Ethernet HWaddr 0a:00:27:00:00:01
inet addr:192.168.66.1 Bcast:192.168.66.255 Mask:255.255.255.0
inet6 addr: fe80::800:27ff:fe00:1/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:2545 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:308371 (308.3 KB)
wlan0 Link encap:Ethernet HWaddr 24:fd:52:c0:1b:b1
inet addr:192.168.2.106 Bcast:192.168.2.255 Mask:255.255.255.0
inet6 addr: fe80::26fd:52ff:fec0:1bb1/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:11724555 errors:0 dropped:0 overruns:0 frame:0
TX packets:7429276 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:16204472393 (16.2 GB) TX bytes:1222715861 (1.2 GB)
iptables on host:
$ sudo iptables -L
[sudo] password for aidan:
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Here's an nmap comparing the host IP and the 'guest' IP:
$ nmap 192.168.66.1
Starting Nmap 6.40 ( http://nmap.org ) at 2015-07-22 13:28 CEST
Nmap scan report for 192.168.66.1
Host is up (0.00015s latency).
Not shown: 995 closed ports
PORT STATE SERVICE
139/tcp open netbios-ssn
445/tcp open microsoft-ds
902/tcp open iss-realsecure
3128/tcp open squid-http
5050/tcp open mmcc
Nmap done: 1 IP address (1 host up) scanned in 0.16 seconds
$ nmap 192.168.2.106
Starting Nmap 6.40 ( http://nmap.org ) at 2015-07-22 13:28 CEST
Nmap scan report for 192.168.2.106
Host is up (0.00015s latency).
Not shown: 995 closed ports
PORT STATE SERVICE
139/tcp open netbios-ssn
445/tcp open microsoft-ds
902/tcp open iss-realsecure
3128/tcp open squid-http
5050/tcp open mmcc
Nmap done: 1 IP address (1 host up) scanned in 0.17 seconds