I lost an NFS connection to a Mac on the LAN. Now I get

mount: 192.168.1.20:/Volumes/Alien failed, reason given by server:
Permission denied

The above Alien directory is owned by edj:100, same uid/gid as on this
Gentoo machine. So are all the subdirectories. I guess, therefore,
that the problem is somewhere on the Linux side. showmount -e seems
correct:
Export list for 192.168.1.20:
/Volumes/Alien 192.168.0.0

As does rpcinfo -p 192.168.1.20
program vers proto port
100000 2 tcp 111 portmapper
100000 2 udp 111 portmapper
100024 1 udp 1021 status
100024 1 tcp 1015 status
100021 0 udp 1008 nlockmgr
100021 1 udp 1008 nlockmgr
100021 3 udp 1008 nlockmgr
100021 4 udp 1008 nlockmgr
100021 0 tcp 1014 nlockmgr
100021 1 tcp 1014 nlockmgr
100021 3 tcp 1014 nlockmgr
100021 4 tcp 1014 nlockmgr
100005 1 udp 989 mountd
100003 2 udp 2049 nfs
100003 3 udp 2049 nfs
100003 2 tcp 2049 nfs
100003 3 tcp 2049 nfs
100005 3 udp 989 mountd
100005 1 tcp 1012 mountd
100005 3 tcp 1012 mountd

fstab entry:
192.168.1.20:/Volumes/Alien /mnt/alien nfs
rw,noauto,noexec,nosuid,nodev 0 0

Any hints as to where to look for some misconfigured file greatly
appreciated. Thanks,