Neb. Rev. Stat. §§ 25-321
When the plaintiff is ignorant of the name of the defendant, such defendant may be designated in any pleading or proceeding by any name, or any name and description, followed by the words, "real name unknown". In any such case the person intended shall thereupon be regarded as a defendant in such action or proceeding and as sufficiently identified therein for all purposes, including service of summons or constructive service when authorized and as prescribed in Chapter 25. In any action wherein it is alleged in the complaint or other pleading that there are persons who have or that there are persons who claim or appear to have some interest in, right or title to, or lien upon any real or personal property within this state involved in such action, and that the ownership of, interest in, rights or title to, or lien upon such property of such persons, does not appear of record, in or by their respective names, in the county wherein such property is situated, and that the plaintiff or person in whose behalf such allegations are made, after diligent investigation and inquiry, is unable to ascertain and does not know the names or whereabouts if in this state, or the residence of such persons, such action may proceed against all such persons designated as "all persons having or claiming any interest in" such property which shall be accurately and definitely described, followed by the words, "real names unknown".
Neb. Rev. Stat. §§ 25-321