nfs nlock

[gigiz]

Hi guys,
i need to close a services that not use.
In my server there is nfs but for security, the security product check tel me to close nflockmgr if i not use it.

I have nfs in my server .
I want to know what happened if i close nfslockmgr but the nfs is active.

[TTr]

nfslockmgr is running at a high port (over 1024) and that is why it is flagged by your security product. If you shut down the nfslockmgr your NFS server will not be functioning properly.

This is a Linux question, hp-ux does not have nfslockmgr.

[Dave Olker]

Yes, HP-UX does have an NFS lock manager. It's implemented via the rpc.lockd daemon and if you disable this daemon then any attempt to lock a file over NFS will likely hang.

If you're concerned about this daemon my advice would be to restrict access to it by using a firewall or IP Filter.

Regards,

Dave

[TTr]

Like I said, HP-UX does not have nfslockmgr. nfslockmgr is the name of the Linux process and not a descriptive english word for the NFS locking mechanism.

[skt_skt]

what is the OS version of HP-UX/Linux

[gigiz]

Why the nfs go in hang if i close nlockmgr?
I try to close it and edit simultaneously from serverA and serverB the file in nfs filesystem, and it work proply. What is the problem ?

[Mark Ellzey]

Gigiz,

The problem comes when more that one process need access to a particular file for update purposes. If this is the case, the last process to modify the file wins; any previous updates are lost.

This may not be a problem for individual text files, but consider a database file mounted via NFS. Multiple processes have access to this file for update purposes, and with no locking control, chaos ensues.

Regards,
Mark

[Dave Olker · Accepted solution]

The hang comes if you have an application that attempts to lock the file. If you have any application that calls fcntl() or lockf() and requests to lock a file in the NFS filesystem it will block because the lock will not get processed - because you shut down the locking protocol.

If you're 100% positive you have no applications that use file locks (like shells, email programs, CAD programs, database programs, etc.) then feel free to disable it. Just make sure you don't get more than one process/thread/client trying to change the same data at the same time.

Dave

[gigiz]

Ok