only one user:

chgrp ats /usr/bin/dumpcap

chmod 4750 /usr/bin/dumpcap # chmod u+s

 

for more users:

groupadd wireshark

usermod -a -G wireshark userName1

chgrp wireshark /usr/bin/dumpcap

chmod 4750 /usr/bin/dumpcap

 

ref:

http://anonscm.debian.org/viewvc/collab-maint/ext-maint/wireshark/trunk/debian/README.Debian?view=markup