No capture interfaces are available in Wireshark running as a non-root user, like samurai, that is, when it runs from the GUI menu.
Solution:
Linux capabilities must be enabled on dumpcap:
$ sudo setcap 'CAP_NET_RAW+eip CAP_NET_ADMIN+eip' /usr/bin/dumpcap
Fix coming soon! :)
SVN rev.17
Fixed in 2.1