Re: NFS in kernel 2.6 and Netapp: privileged ports problem

[Steve Dickson <SteveD@redhat.com>]

Filipe Brandenburger wrote:
> I'm having problems when mounting NFS in a Netapp FAS 740 filer on a
> Linux RHAS4 Kernel 2.6 client. The message I get is:
> 
> [root@talara ~]# mount -a
> mount: RPC: Authentication error; why = Client credential too weak
Your running out of privileged ports....

The problem is the glibc pmap_getport() routine uses
privileged ports to get ports from portmapper (when TCP
is specified) which is wrong. So these ports end up in
TIME_WAIT, which makes them (temporary) unusable for mounts.
(Do a netstat -an | grep TIME_WAIT and notice all the ports are < 1024).
Now, when a privileged port is not available, a normal port (i.e. >
1023) will be used which will cause the above message.

Note: the glibc is fixed in FC4 and in upcoming RHEL3 and RHEL4
releases.

> Sometimes it works, most times it fails with the message above. If I use
> the same setup above but with RH7.3 Kernel 2.4, it works without a
> problem.
This is because UDP is the default protocol for mounts where as with
later releases TCP is the default.

> 
> So I ask:
> 
> - Anyone experienced this too?
Yes... see https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=154678

> - Is there a way on kernel 2.6 to force it to use privileged ports to do
> the mount?
I don't think so...

> - This one is not related to Linux, but anyone knows if it's possible to
> disable the privileged port restriction on the Netapp filer? This would
> be acceptable to me to solve this problem.
You could try adding 'insecure' to your exports options... and
you could also try using UDP mounts by specifying the '-o udp'
mount option.

steved.




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