What applications would be expected to setup a network interface "stf0" and "gif0" I've recently noticed that I have the following network interfaces setup on my mac:

Ethernet
Airport
Firewire
vmnet1
vmnet8
gif0
stf0

Obviously Ethernet, Airport, and Firewire are enabled by default.  I think vmware setup vmnet1 and vmnet8.  Where did gif0 and stf0 come from?  I'm sure I did not setup these interfaces myself, so now I'm getting paranoid about spyware.

What applications might have automatically setup these interfaces? How do I disable networking through them?  Or is this a common setup and I shouldn't worry about it?

/edit: gif0 appears to have the ip address 55.4.0.0 and stf0 appears to have the ip address 57.4.0.0.  Neither one of those is even remonetly similar to my actual ip address.  What's going on here?

/edit 2: ifconfig reveals that neither interface has the flag "up" so they are not in use.  Thanks for the help jjungnickel.
Those are Tunnel-Interfaces. They are commonly used to provide IPv6- or VPN-Services. They are usually always active, but not connected unless you set up your system to use them. 

You can determine if an interface is enabled but not active by observing its flags using ifconfig &lt;interfacename&gt; to not contain UP. 

You can look up the definition for those interfaces on the terminal with man gif or man stf, respectively.