Many networking programs can print this message, including from(1B), lpr(1B), lprm(1B), mailx(1), rdist(1), sendmail(1M), talk(1), and rsh(1). The command prints this message when it cannot locate a password file entry for the current user. This error might occur if a user logged in just before the superuser deleted that user's password entry, or if the network naming service fails for a user who has no entry in the local password file.
If a user's password file entry was accidentally deleted, restore it from backups or from another password file. If a user's login name or user ID was changed, ask that user to log out and log in again. If the network naming service failed, check the NIS server(s) and repair or reboot as necessary.
A known problem exists with starting hundreds of rsh(1) processes on another machine. This message appears because rsh(1) hangs while binding to a reserved port and responds too slowly to interact with the network naming service.