VM-VM only network with KVM

I'm trying to create a VM only network where guests can speak to each other, but not with the host. I want to isolate the host for security reasons, as multiple test users will be using the VMs.

Currently I have a fedora 22 box with multiple windows/fedora/freebsd guests. It has two network interfaces, one for the host and the second tied to a bridge called "bridge0"

# cat /etc/sysconfig/network-scripts/ifcfg-bridge0
DEVICE="bridge0"
ONBOOT="yes"
TYPE=Bridge
BOOTPROTO=static
IPADDR=192.168.1.2
NETMASK=255.255.255.0

# cat /etc/sysconfig/network-scripts/ifcfg-enp4s0f1
TYPE=Ethernet
BOOTPROTO=static
NAME=enp4s0f1
DEVICE=enp4s0f1
ONBOOT=yes
NM_CONTROLLED=no
BRIDGE=bridge0

# brctl show
bridge name     bridge id               STP enabled     interfaces
bridge0         8000.0010183803ce       no              enp4s0f1
                                                        vnet0
                                                        vnet1
                                                        vnet2
virbr0          8000.5254000a60a5       yes             virbr0-nic

Is this as simple as creating another bridge "bridge1" and not attaching a physical interface AND not assigning an ip address?

Yes, As Michal Sokolowski said :)

The method would be to:

1. create the guest-only-bridge (and have it "up" :)
2. disable the IPv6 on that bridge interface (Something that's "default to create/setup a link local IP O_o )
3. attach the KVM guests' interfaces to that guest-only-bridge
4. on the guests, have either one of them act as DHCP server and the rest as dhcp clients, or else assigned fixed IPs to each of the guest VM's interfaces attached to that guest only bridge.

This is something that I do all the time, as I have a pfSense (nice GUI ;) ) as a firewall for my "internal" VMs where the pfSense does the DHCP for me too :)

I'm doing this especially on ProxMox (KVMs) for client setups, but also with VMWare Fusion and with Paralels Desktop on my MacOSX systems :)