The simple way how to start Wireshark on Linux is to type:

wireshark

If you run this command as a normal user you won’t be able to capture packets. In order to dump packets, you need to execute it as root. This must be done in a specific way. If try just sudo you’ll end up with interesting errors like:

Attempt #1

$ sudo su
# wireshark
QXcbConnection: Could not connect to display 
Aborted (core dumped)

Attempt #2

$ sudo wireshark
QXcbConnection: Could not connect to display 
[1]    8836 abort      sudo wireshark

The proper way how to start Wireshark is by gtk-su:

xdg-su -c wireshark