Network Information Service (NIS) B.11.31.02 Administrator's Guide

Logging in Issue with NIS
This section suggests a way to correct a common logging in problem encountered with NIS.
If you are using NIS compat mode, make sure the NIS escape entry in the /etc/passwd file
on the client does not have an asterisk in the password field.
For example, on HP systems, the NIS escape entry in the /etc/passwd file is:
+::::::
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