enable your root account in the Directory Utility unter the Utilitys in Applications:
then enable it:
In order to capture packets with wireshark, you must have read access to the BPF devices in /dev/bpf*.
so open the terminal, login as root and type:
chmod o+r /dev/bpf*
see http://wiki.wireshark.org/CaptureSetup/CapturePrivileges
