please try below steps and also refer this link http://packetlife.net/blog/2010/mar/19/sniffing-wireshark-non-root-user/
root@test:/usr/bin# setcap cap_net_raw,cap_net_admin=eip /usr/bin/dumpcap
root@test:/usr/bin# getcap /usr/bin/dumpcap
/usr/bin/dumpcap = cap_net_admin,cap_net_raw+eip
root@test:/usr/bin# exit
exit
test@test:/usr/bin$ tshark -V -i eth1
Capturing on eth1
Frame 1 (60 bytes on wire, 60 bytes captured)
Arrival Time: Aug 8, 2013 13:54:27.481528000
[Time delta from previous captured frame: 0.000000000 seconds]
[Time delta from previous displayed frame: 0.000000000 seconds]