Guest,
perhaps you might consider registering since your posting doesn't really provide much information about your dog to figure out what might be wrong. Such as:
How old is he? (old dog or young dog)
The people he's been snapping at, what have they been doing? Sitting alone, petting him, coming in the door, trying to pick him up?
Is it specific individuals that he's taken a dislike to?
Is he in good health? Dachs have troubles with their long backs and disc trouble causes much pain.
Snapping can be a sign of aggression, pain, fear, illness, and even tiredness. So more details are really needed to try to determine what the cause could possibly be.
regards,
toodles