The error “/usr/bin/dumpcap permission denied” appeared when executing wireshark as a normal user. Using package manager to install wireshark may encounter this problem.
This is solved by adding normal user into group wireshark:
gpasswd -a cyrus wireshark
Check to see if you are in the group wireshark:
cat /etc/group |grep wireshark
Once ensure your username is in group wireshark, logout and login again, you will not get the error again and can sniff the network via chosen interface.