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In the middle of installing a tool called mrtg, I bailed out from a perl script to set various configuration parameters for use of snmp because it became clear that I had no idea what I was doing. I also explored some snmp commands myself, but didn't keep a record, unfortunately.

I come back to ifconfig and notice it shows three new interfaces (not there just before the previous adventure):

gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280
stf0: flags=0<> mtu 1280
fw0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 4078
    lladdr 60:fb:42:ff:fe:f4:cd:9e 
    media: autoselect <full-duplex>
    status: inactive

My laptop on the same LAN has a different new interface called p2p0 that I hadn't noticed before, as well as gif0 and stf0 but not fw0.

After I reset my Airport Extreme to factory default, and reinstalled OS X Lion on my machine, with a wiped disk, they are still there. This:

sudo ifconfig gif0 destroy

makes gif0 go away, but on reboot it comes back. There is a previous answer with some info but what I'd like to know is why are they still there despite a clean install, could they be a security risk, and should I or can I make them go away. Should I be looking at the Airport or something in my StartupItems?

UPDATE: Does my machine set these up at boot or does the Airport remember them? And in either case, why didn't a clean install (or factory reset) restore them to the previous configuration?

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3 Answers 3

up vote 7 down vote accepted

fw0 is the FireWire network interface. It's benign.

stf0 is an IPv6 to IPv4 tunnel interface. It's a bridge connection that exits to help us transition from IPv4 to the IPv6 standard. It's benign. You can read more about it here if you like: http://en.wikipedia.org/wiki/6to4

gif0 is a generic tunnel interface. It's used to tunnel IPv4 traffic to an IPv6 network and back. It's benign. You can read more about it here: http://www.gsp.com/cgi-bin/man.cgi?section=4&topic=gif

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1  
As to why the interfaces appeared, my best guess is that while they showed up after the snmp adventure, they weren't caused by it. FWIW, fiddling with Network Prefs does not change output of a plain ifconfig (including deleting FireWire as shown in the answer. A change to the IPv6 configuration in Network Prefs is reversed by a reboot. –  telliott99 Apr 3 '12 at 18:27
    
@telliott99 thanks. Edited. –  Ian C. Apr 3 '12 at 18:32
    
I have a p2p0. Any explanations? –  Yasky Apr 23 '13 at 10:31
    
If it has an IPv6 address in the block fe80::/64 it's a local link interface. –  Ian C. Apr 23 '13 at 16:37

The gif0 is a generic virtual interface, stf0 is an ipv6 interface and fw0 is your firewire interface. You shouldn't worry about these.

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p2p0 interface belong to VirtualBox, after you installed VB into my Mac, you will get this interface.

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I have never installed VirtualBox but I have this interface in my Macbook Pro. –  vquintans Jun 18 at 8:35

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