Alright, quick fix for a problem I always forget. When running Wireshark on OS X, when I go to select an interface to capture on, I get an error telling me there are no available interfaces to capture on. This is because Wireshark is running as a user that doesn’t have ownership on these interfaces.
Solution, open up the terminal and run the command:
sudo chown <username> /dev/bpf*
After a reboot, these permissions get reset, so you need to do it after each reset (and hence why I need this every now and then but can never remember the command).
Justin Carmony 
Better solution:
Inside the disk image for Wireshark that you downloaded is a folder called Utilities.
Inside the Utilities folder is a StartupItem called ChmodBPF. Simply copy that to your StartupItems folder (shortcut provided). Now your /dev/bpf* files will always be accessible to you.
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