File permissions on NFS mount show up as 'nobody' after upgrading to 14.04

I have an Ubuntu 12.04 server that exports a couple of filesystems over NFS.

server$ cat /etc/exports /home 192.168.42.0/255.255.255.0(rw,anonuid=65534,anongid=65534,async,no_subtree_check) /stuff 192.168.42.0/255.255.255.0(rw,anonuid=65534,anongid=65534,async,no_subtree_check) /stuff 192.168.99.0/255.255.255.0(ro,anonuid=65534,anongid=65534,async,no_subtree_check) 

I also have a client that mounts them:

client$ cat /etc/fstab ... server:/home /home nfs hard,intr,rsize=8192,wsize=8192,_netdev 0 0 server:/stuff /server/stuff nfs hard,intr,rsize=8192,wsize=8192,_netdev 0 0 

The client's IP is in the 192.168.42.x range. It was running Ubuntu 10.04 until yesterday. NFS worked fine, more or less (sometimes it wouldn't automount on boot, but I had a cron script to detect and fix that).

I upgraded the client to Ubuntu 12.04 yesterday and rebooted. NFS continued to work fine.

I upgraded the client to Ubuntu 14.04 today and rebooted. Now NFS is mounted but all file ownership information is mapped to nobody:4294967294:

client$ ls -ld /home/weblate drwxr-xr-x 5 nobody 4294967294 4096 Jan 29 2014 weblate 

Why is that and what do I need to do to make file ownership work again?

2 Answers

The vital clue showed up in /var/log/syslog:

Sep 16 13:11:07 client nfsidmap[7340]: nss_getpwnam: name 'www-data@lan' does not map into domain 'localdomain' 

combined with this excerpt from NFSv4Howto

If all directory listings show just "nobody" and "nogroup" instead of real user and group names, then you might want to check the Domain parameter set in /etc/idmapd.conf. NFSv4 client and server should be in the same domain.

and this comment in /etc/idmap.conf:

# set your own domain here, if id differs from FQDN minus hostname # Domain = localdomain 

So turns out my server thought its domain was lan:

server$ hostname -f server.lan server$ grep server /etc/hosts 127.0.1.1 server.lan server 

while my client didn't have a domain:

client$ hostname -f client client$ grep client /etc/hosts 127.0.1.1 client 

The fix: edit /etc/hosts on the client to read

127.0.1.1 client.lan client 

and reboot.

I resolved my issue by this method. Open the file /etc/nfsmount.conf and find Nfsvers=.

Uncomment that line and write the NFS version which is supported by your server. Mine was 3 so I wrote:

Nfsvers=3 

The I restarted the NFS server.