How do you get rid of a smelly drain?

http://homeguides.sfgate.com/rid-smells-sink-28092.html

Try dumping about 1/2 cup baking soda down the drain, then about a cup of white vinager. It will foam up, so don't panic. Let sit for a bit, 30 min or so, then run hot water down the drain. I do this to all the drains in my house about once a month. It keeps drains smelling fresh, keeps the goop from building up and I've never had a clogged shower drain.

Chop up a lemon and grind it in the disposal. Grind up everything each time you put something down the disposal, keeping the disposal empty.

I clean my disposal with lemon slices and some ice.fyi if you don't use your sink much your trap could emit smell from the sewer line I've never heard that happening in a kitchen Sink.. My basement has done that and the drain would dry out so I would pour water in it.The water keeps the sewer gas from coming back through the trap.You must use the kitchen sink every day so that may not be the problem .😊😊

Try putting lemons in garbage disposal with ice cubes, turn it on with out water for a minute, then turn on hot water run for another minute.

backing soda and vinegar