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I'm trying to share a some files on a Mac running Snow Leopard with a Ubuntu Linux.

The mount request gets a "permission denied", and a client system log contains "host xx requires a stronger authentication"

I've seen this problem referred to elsewhere, but no solution. This is a hack on a home network, and I really do want to "just do it" and damn the security flaws.

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migrated from stackoverflow.com Sep 1 '10 at 19:08

This question came from our site for professional and enthusiast programmers.

Same error here, except that the Linux instance is running in a virtual machine (QEMU). Adding -o nfsvers=3 does not help; mount -v clearly shows that protocol negotiation is occurring and successful.

The problem is that the mount request comes from an unprivileged port; putting

nfs.server.mount.require_resv_port = 0

in /etc/nfs.conf on the Mac and notifying the running server (sudo nfsd update) fixes it for me.

Note: here is what the man page has to say about that option—and its security implications:

 nfs.server.mount.require_resv_port
          This option controls whether MOUNT requests are required to
          originate from a reserved port (port < 1024).  The default value
          is 1 (yes).  Many NFS server implementations require this
          because of the false belief that this requirement increases
          security.
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You are probably using NFSv4, which implements kerberos. Try specifying the nfs version for 3 in your mount command & see if it works. Also, you do know that UID/GID's need to be identical on both systems right?

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You need to specify nfsvers=3. – churnd Sep 13 '10 at 3:16

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