# nxc vnc > Pentest and exploit VNC servers. > More information: . - Search for valid credentials by trying out every combination in the specified lists of usernames and passwords: `nxc vnc {{192.168.178.2}} {{[-u|--username]}} {{path/to/usernames.txt}} {{[-p|--password]}} {{path/to/passwords.txt}}` - Avoid rate limiting through VNC-sleep: `nxc vnc {{192.168.178.2}} {{[-u|--username]}} {{path/to/usernames.txt}} {{[-p|--password]}} {{path/to/passwords.txt}} --vnc-sleep {{10}}` - Take a screenshot on the remote system after waiting the specified amount of time: `nxc vnc {{192.168.178.2}} {{[-u|--username]}} {{username}} {{[-p|--password]}} {{password}} --screenshot --screentime {{10}}`