puTTY serial (ttyUSB0) only works when run as root?

Question

Today I had to configure some CISCO switches & routers at school, and I used a USB to serial adapter. Unlike on Windows I didn't have to install any drivers; it was recognized immediately.

When I open puTTY through GUI and tried serial /dev/ttyUSB0 I got the following error:

Unable to open connection to /dev/ttyUSB0
Unable to open serial port

I thought I'd give it a try with root permissions sudo putty and it worked, but why!?

If I do have to give root permissions to puTTY what would be the way to do it? I read gksudo is removed from 18.04 and running an app as sudo <> is not recommended.

Thanks in advance!

Solution

Hit sudo adduser $USER dialout in terminal

Then log out & log back in again for this to take effect and try connect tty without root.