Contrary to what television shows may imply, police in Nebraska cannot simply burst into your home with a drug dog and search it for drugs. In fact, the Nebraska Legislature points out that not only does the United States Constitution's Fourth Amendment make unreasonable searches and seizures illegal, Nebraska's Constitution also provides this protection.
Police have to have probable cause and receive a warrant from the court before they can search your home, with or without a drug dog. To get this, they have to explain their reasoning for searching your home under oath to the judge, as well as what it is they plan to seize if they do find it there. However, if they do get the warrant, they do not necessarily have to knock before entering, and if there is an illegal substance in plain view, even if it is not listed on the warrant, police may still seize it.
The protection you have in your home stems from your right to privacy, but does this include the hallway outside your door? According to the state constitution, your right to privacy extends from your door to the hallway in the immediate vicinity of your apartment. So, law enforcement cannot bring a drug-sniffing dog into the hallway right outside your door without a warrant.
Your right to privacy may not extend to your garbage once it is taken out and left for collection outside of the area of the building, so an officer with a drug dog may not need a warrant to walk around the dumpster or other waste container. Because there are some factors that may be open to interpretation by the law, this information should not be taken as legal advice.