Comment 4 for bug 1322407

/etc/exports has one line that is not a comment:

/home 192.168.1.0/255.255.255.0(rw,sync,root_squash,no_subtree_check)

/etc/defaults/nfs-common:

NEED_STATD=no
# Options for rpc.statd.
STATDOPTS=
# Do you want to start the gssd daemon? It is required for Kerberos mounts.
NEED_GSSD=no

/etc/defaults/nfs-kernel-server

# Number of servers to start up
RPCNFSDCOUNT=8
# Runtime priority of server (see nice(1))
RPCNFSDPRIORITY=0
# Options for rpc.mountd.
RPCMOUNTDOPTS="--manage-gids"
# Do you want to start the svcgssd daemon? It is only required for Kerberos
# exports. Valid alternatives are "yes" and "no"; the default is "no".
NEED_SVCGSSD="no"
# Options for rpc.svcgssd.
RPCSVCGSSDOPTS=""
# Options for rpc.nfsd.
RPCNFSDOPTS="--debug --syslog"

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Note that I tried several alternatives, such as

RPCMOUNTDOPTS="--manage-gids --no-nfs-version 4"

and other combinations, to no effect. I am mounting Ubuntu 12.04 clients. The relevant entry in /etc/mtab for one of these clients looks like this:

192.168.1.2:/home /mnt/nfshome nfs rw,vers=4,addr=192.168.1.2,clientaddr=192.168.1.9 0 0

The client's nfs-common version is 1:1.2.5-3ubuntu3.1. Also, it makes no difference whether I use mount -t nfs or mount -t nfs4 (in the first case the /etc/mtab entry has vers=4 in the options, in the other case it does not, but the filesystem type is nfs4.