When I go to concerts, I set the camera on auto iso up to 6400 and use TV mode to control shutter speed. People say no slower than 1/focal length, but if you are super steady you can probably get away with something slightly slower although not by much. If you have a fast lens then that will help. I don't so I settle for the images that I manage to get and hope for some good ones in there. Sometimes a little motion blur adds to the photo, such as the movement of a drummer's hands. And sometimes they use really bright lights in between so that's a good opportunity for you to get a better picture.
This picture is one of my favorites. He was practically standing still and the lights were at full brightness. So there are ideal conditions for a decent picture if you if you know when to take advantage.
There was a lot of movement at this concert, and only a fraction of the pictures I took came out satisfactory, but a fast enough shutter can "freeze" movement
Hope that helps.