He is teething and just like a baby chewing on your fingers to relieve the pressure the pup is playing and chewing on the rubbery hand to do the same. Have lots of chew toys around for him by the couch when people are there. When he starts chewing, tell him no and give him a chew toy and tell him to go lay down. If he insists, then put him in his crate with the chew toy - nothing that will choke him as when you are visiting it is easy to get side tracked. Red's advice with the leash is good too. Good luck.