can you (theoretically) run only NFSv4 (without earlier versions)?

[Robert P. J. Day]

Quoting Ed Greshko <Ed.Greshko at greshko.com>:

> On 12/24/13 07:16, Robert P. J. Day wrote:
>> Quoting Tom H <tomh0665 at gmail.com>:
>>
>>> On Fri, Dec 20, 2013 at 2:34 PM, Robert P. J. Day  
>>> <rpjday at crashcourse.ca> wrote:
>>>>
>>>> a long, long time ago, i reported an apparent glitch with NFS on
>>>> fedora:
>>>>
>>>> https://lists.fedoraproject.org/pipermail/users/2010-January/097465.html
>>>>
>>>> in that, at the time, it *appeared* that you couldn't set up
>>>> NFS so that *only* version 4 was running. before i start messing
>>>> with this again, anyone know whether that's changed? that is,
>>>> is it possible to set up a network in which only NFSv4 is running,
>>>> and no earlier versions are supported? thanks.
>>>
>>> It's been possible to run nfsv4-only nfs for a long time, with only
>>> port 2049 being let through the firewall. It only appears that you
>>> can't because because rpc.mountd has to run on the server but it's
>>> only involved in the exporting and not the mounting.
>>
>>   how does one configure fedora 20 to support only NFSv4? i'm used to
>> mucking with /etc/sysconfig/nfs in earlier versions of RH, and tweaking
>> the variables MOUNTD_NFS_V* and RPCNFSDARGS. i don't see those vars
>> in fedora 20 and, according to "rpcinfo -p", i'm currently supporting
>> NFS versions both 3 and 4. so how does one turn off NFSv3? thanks.
>>
>>
>
> In /etc/sysconfig/nfs
>
> # Optional arguments passed to rpc.nfsd. See rpc.nfsd(8)
> RPCNFSDARGS=""
>
> man 8 rpc.nfsd
>
>       -N  or  --no-nfs-version vers
>               This option can be used to request that rpc.nfsd does   
> not  offer
>               certain versions of NFS. The current version of  
> rpc.nfsd can sup‐
>               port NFS versions 2,3,4 and the newer version 4.1.
>
> Would seem to be what you are searching.

   i tried that and it didn't seem to work, in the sense that when i
ran "rpcinfo -p" to verify the result, here's part of the output:

     100003    3   tcp   2049  nfs
     100227    3   tcp   2049  nfs_acl
     100003    3   udp   2049  nfs
     100227    3   udp   2049  nfs_acl
     100003    4   tcp   2049  nfs
     100003    4   udp   2049  nfs

so isn't that telling me i still have both versions 3 and 4? here's
the line i added to the file:

RPCNFSDARGS="-N 2 -N 3"

rday