Recently, some users have reported that, on MAC OS X 10.6.5 and 10.6.6, if the MobileMe feature of “Back-to-My-MAC” is turned on, then it’ll shut down the other virtual interfaces (like Remobo’s tap0) while launching its own “utun0” virtual interface. This problem can be observed from the output of ‘ifconfig’ commands:

# ifconfig
…..
…..
tap0: flags=8842<BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether 80:a1:65:15:50:ce
open (pid 20988)
utun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
inet6 fe80::ca2a:14ff:fe10:67f6%utun0 prefixlen 64 scopeid 0×8
inet6 fd00:6587:52d7:b1:ca2a:14ff:fe10:67f6 prefixlen 64

Notice that there’s no inet IP address associated with tap0, and the “UP” flag of tap0 is missing, while utun0 is UP.

This is a bad behavior (& bug) of “Back-to-My-MAC”, in our opinions, and it doesn’t happen prior to MAC OS X 10.6.4. MobileMe has quite a few troubles in the past years; even Steve Jobs doesn’t like it (Apple should have just replaced MobileMe with Remobo :-). We’re building workarounds within Remobo to solves this issues, by having Remobo to recover the damage done by Back-to-My-Mac, so that you don’t have to be aware of it. Meanwhile, before our solution is out in the next release of Remobo, if you observe the problem above while Remobo is logged in, you can manually fix this problem by running this command:

# ifconfig tap0 netmask 255.0.0.0 up"

,where can be found at the bottom of the Buddy-List window in Remobo.