I'm trying to mount an NFS drive, but I am getting an RPC Authentication Error, with the reason given as that the credentials are too weak.

On the server side (, it looks like the NFS server and mount daemon are starting and being available to the target client (

# cat /etc/exports
/datastore/winmedia -ro
# portmap
# nfsd -tun 4
# mountd
# showmount -e
Exports list on

However, when trying to mount the disk on the client-side, I receive an RPC Authentication Error

# ls /mnt/winmedia
# mount -v /mnt/winmedia
mount: no type was given - I'll assume nfs because of the colon
mount: RPC: Authentication error; why=Client credential too weak

Looking on the server logs, it only says that the connection was refused, but doesn't give a reason.

Feb 11 23:43:25 fattyopenbsd mountd[16785]: Can't open /var/db/mountdtab: No such file or directory
Feb 11 23:48:41 fattyopenbsd mountd[16785]: Refused mount RPC from host port 62826

On the client side, rpcinfo shows the same data as on the server side, except without the program names.

Server side rpcinfo:

# rpcinfo -p
program vers proto    port
100000     2   tcp     111  portmapper
100000     2   udp     111  portmapper
100003     2   tcp    2049  nfs
100003     3   udp    2049  nfs
100003     2   tcp    2049  nfs
100003     3   udp    2049  nfs
100005     1   udp     630  mountd
100005     3   udp     630  mountd
100005     1   tcp     612  mountd
100005     3   tcp     612  mountd

And on the client side, same thing but no process name

# rpcinfo -p
program vers proto    port
100000     2   tcp     111  
100000     2   udp     111  
100003     2   tcp    2049  
100003     3   udp    2049  
100003     2   tcp    2049  
100003     3   udp    2049  
100005     1   udp     630  
100005     3   udp     630  
100005     1   tcp     612  
100005     3   tcp     612  

So, my questions are 1) Why is the mount being refused? (Is there a way to get more detailed information about the failed request?) 2) How can I make the NFS drive be mounted?

The server is running OpenBSD 5.8 The attempting client is Puppy Linux, and is a VirtualMachine on a Windows machine. (Not sure if the VM IP is an issue. If I run ifconfig on the client, it shows a 10.0.*.* address on eth0, but the Windows host has the 192...101 address over wireless. I figured since the server log shows the request coming from the ...101 address, the VM issue is probably not an issue, but if I am wrong any suggestions would be great).

UPDATE I now believe this issue is related to the VMs network settings. The request to the server is coming from a Non-privileged port number ( >1024) on the VM's host machine.

The VM is using NAT, so even if the VM uses a privileged port when making the request, this is not reflected in the final request.

This should be fixable by using a bridge connection to the host instead of NAT, which would cause the requesting IP and port to be the same as the VM, but sadly I have only wifi at my place and couldnt get the bridged connection working with wifi adapter.

Solution: use Samba instead of NFS, so that a username and password are used for authentication instead of uid, ip address, and client side port number.

  • Honestly I don't know if the older version argument in the post linked is relevant to you but you can turn on the insecure mode of rpcbind ON and try mounting your NFS. stackoverflow.com/questions/13111910/rpc-authentication-error
    – MelBurslan
    Feb 11, 2016 at 15:23
  • Thanks, I saw that post, but the server doesn't have an rpcbind command, and I haven't found any analogous program or program
    – hilcharge
    Feb 11, 2016 at 15:34
  • On OpenBSD, you use portmap instead of rpcbind. Feb 11, 2016 at 16:32
  • right, I am using portmap but it has no insecure option. so, it is portmap that is checking the credentials? honestly I am a little lost as to what credentials really mean in nfs context, and how they relate to normal OS logins
    – hilcharge
    Feb 12, 2016 at 11:45

1 Answer 1


In my case elevating the privileges on the client's side (doas/sudo) did the trick;

a485$ mount -t nfs ~/Torrents 
mount_nfs: bad MNT RPC: RPC: Authentication error; why = Client credential too weak
a485$ doas mount -t nfs ~/Torrents

The unprivileged request was originating of a very large port number;

Aug  7 12:25:36 t440p mountd[87312]: Refused mount RPC from host port 15630

If I'm interpreting the netstat -a output correctly, the active connection from an 'elevated' request originates of port 901 (irrelevant output ommited);

a485$ netstat -a
Active Internet connections (including servers)                                                                                                                                                                    
Proto   Recv-Q Send-Q  Local Address          Foreign Address                                                                                                                                                                                                                                                                              
udp          0      0  a485.901               t440p.nfsd

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