pam doesn't see nis

[Peter Nome <peter@cogweb.net>]

I've been running into a problem with NIS on Debian -- everything looks like it should be working, but logins fail with pam saying "user unknown".

Here's an example -- I can change the password, so clearly NIS is working, yet at the end the login fails:

root@jellyfish:~# yppasswd student
Changing NIS account information for student on graywhale.
Please enter root password:
Changing NIS password for student on graywhale.
Please enter new password:
Please retype new password:

The NIS password has been changed on graywhale.

root@jellyfish:~# su student
su: Authentication service cannot retrieve authentication info.
(Ignored)
student@jellyfish:/root$

Here's what my auth.log says when I try ssh jellyfish -l student:

Aug 20 01:02:51 jellyfish ssh(pam_unix)[21143]: check pass; user unknown
Aug 20 01:02:51 jellyfish ssh(pam_unix)[21143]: authentication failure; logname= uid=0 euid=0 tty=NODEVssh ruser= rhost=graywhale

I saw someone post the identical problem to debian-users (and receive no reply), so I guess it affects a number of people.

Oh, and I should mention: I had this working! Late July, after the last nis upgrade. I did some other upgrade, no idea what, and got the problem. ypcat passwd and all kinds of other NIS map commands work fine. 

This is an updated Debian sid running nis 3.9-6.3. I'm setting this up for a high school lab (remotely), and we're all ready to go aside from this.

Please cc me -- any suggestions much appreciated! I'm happy to suppy more information.

Cheers,
Peter