Nested groups support?

Bogdan Iamandei bogdan at
Thu Jan 15 01:35:55 GMT 2004

Marc Kaplan wrote:
>>-----Original Message-----
>>From: Volker Lendecke [mailto:Volker.Lendecke at SerNet.DE]
>>I already thought about such a thing. You only run into the 
>>Unix 16- or
>>32-groups per user limit far too soon.
> There is an kernel/glibc patch for the 32 group problem on Linux that a few
> sites have tested. I am using it without problem, except that ps returns an
> Internal error when viewing the PIDs with more than 32 groups. Tridge showed
> me where this patch was, and I could attach the patch if anybody is
> interested. The way it's currently implemented it adds support for 256
> groups, but I think that could be extended if needed.

Erm. Ok, before this happens - please make a note to the users that
increasing the number of groups a user can be part of may horribly
break NFS. I am not sure how NFS is implemented with regards to this
on Linux, but on Solaris it's a bit of a problem if you go over 16.

Here's the FAQ ID on Sunsolve which deals with it: Free FAQ ID: 01247

Note: Do not raise the value of NGROUPS_MAX above 16 for systems that 
need to be NFS clients as this will break NFS authorization and those 
users will not be able to login because NFS internally depends on 
NGROUPS_MAX and is limited to only 16.

Also, while booting up, the following message is displayed on the console:

WARNING: ngroups_max of 32 > 16, NFS AUTH_SYS will not work properly


I have seen things you people wouldn't believe.  Attack ships on fire
off the shoulder of Orion.  I watched C-beams glitter in the dark
near the Tannhauser Gate.  All those moments will be lost in time,
like tears in rain.  Time to die.

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