[CentOS] Update to EL 6.3 breaks TCP NFS automounts

Wed Aug 8 22:37:20 UTC 2012
Cal Webster <cwebster at ec.rr.com>

See Red Hat Bugzilla bug #846852 for details.


We discovered that after updating to EL 6.3 on our x86_64 server, autofs
5.0.5-54 broke our nightly backups that rely on automounting an NFS
share hosted on another EL 6 machine on our local network. The machine
hosting NFS server was configured to allow only TCP connections to the
port specified by MOUNTD_PORT in "/etc/sysconfig/nfs"

Any attempts to access this share caused segmentation faults in the
automount daemon.

EL 6.2 hosts that had not yet been updated had no problems accessing the
same NFS shares.

While testing we found that opening the UDP MOUNTD_PORT on the NFS
server firewall allowed successful access to the NFS shares from the EL
6.3 NFS client without segfault. Closing the port caused the EL 6.3 NFS
client to return to the faulty behavior.

On another fully updated EL 6.3 i386 host, we were able to duplicate the
same symptoms.

On one of the EL 6.2 hosts not yet updated we confirmed no issues with
the previous autofs package, then upgraded only autofs. After the
upgrade we confirmed symptoms identical to the fully updated 6.3

While filing the bug report I found 2 other, possibly related, bugs
written against autofs 5.0.5-54 that did not describe our symptoms but
may be relevant to other users on this list.

Bug 840025 - autofs 5.0.5-54 fails to mount share on IPv6 netapp 

Bug 834641 - autofs requires portmapper on server for NFSv4 mounts 


For now, we are leaving the UDP NFS port open on the firewall of the NFS
server. Our networks are completely isolated from the outside world so
this doesn't pose a significant risk. However, this may not be
acceptable for everyone's environment.