Bug 168383 - mountd / tcp_wrappers not honoring NIS netgroup
mountd / tcp_wrappers not honoring NIS netgroup
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: nfs-utils (Show other bugs)
i386 Linux
medium Severity medium
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Assigned To: Steve Dickson
Ben Levenson
Depends On:
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Reported: 2005-09-15 11:42 EDT by Joseph Kotran
Modified: 2010-06-07 01:26 EDT (History)
5 users (show)

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Fixed In Version:
Doc Type: Bug Fix
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Last Closed: 2010-06-07 01:26:09 EDT
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Description Joseph Kotran 2005-09-15 11:42:26 EDT
Description of problem:

Via tcp_wrappers and NIS we restrict access to desktop client NFS shares to
members of an NIS netgroup called @trusted_clients.  The Red Hat 4 mountd does
not honor netgroup membership.  As a work around I had to switch to IP based
access control.

Version-Release number of selected component (if applicable):


How reproducible:

Every time

Steps to Reproduce:

1. NIS directory service required.  Netgroup should contain a list of trusted

2. Tcp_wrappers should be configured as such:


ALL EXCEPT sshd: @trusted_clients
sshd: ALL


ALL: ALL: spawn (/usr/sbin/safe_finger -l @%h | /bin/mail -s %d-%h root) &

3. Attempt to mount an Red Hat 4 NFS share from a trusted member of netgroup.
Actual results:

On NFS client: Permission denied.

On RedHat 4 NFS share server: Tcp_wrappers / mountd will deny the access request
and email the output of safe_finger to root@foo.com.

Note: The safe_finger output reports the client via IP, short hostname, and
fully qualified DNS hostname:


Expected results:

The NFS mount should succeed.

Additional info:

As a work around I setup tcp_wrappers /etc/hosts.allow as follows:

ALL EXCEPT mountd sshd: @trusted_clients
sshd: ALL
Comment 3 Joseph Kotran 2005-10-22 10:16:05 EDT
I understand that RedHat advises customers to use IPTables instead of TCP
Wrappers.  Please note that this suggestion is not valid for a corporate LAN
environment.  We are trying to prevent Windows clients from NFS mounting Linux
shares.  The Windows and Linux clients are in the same IP space / pool.

We would have to readdress to accomidate IP TAbles usage.  That is not practical
because boxes often switch to / from Windows and other boxes are dual booted.

- Joe Kotran
Comment 6 chantra 2007-11-04 12:36:09 EST
Hi Joe,

Even thugh this bug report is 2 years old, I gonna give it a try.

I think I encountered the same issue with sshd service.
I set up netgroup to use an ldap backend. 
I found out that I needed to reload the service after the change were made in
/etc/nsswitch.conf in order to have tcpd resolving the netgroup.

This does not happen on a fedora 7. any changes made are directly taken into
account (which is the expected behaviour).

Can you confirm this?

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