NFS


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Summary

NFS is pretty sweet for convenient, insecure, access to remote files. I say insecure, but with tunnels and VPNs, NFS can be made more secure.

NFS Server

Setting up an NFS server is probably easier than you might think. Here's some important components:

Mounting an NFS Export

Similarly, mounting an NFS export can be easy too! I needed to install nfs-common and portmap on the client. Then, its as simple as: 

mount nfs.example.com:/path/to/export /target/mount

It can also be done with /etc/fstab: 

172.16.2.47:/ /home/all/nfs nfs4  _netdev,noatime,rsize=8192,wsize=8192,user,hard,rw,timeo=4,intr,proto=udp 0 0

Debugging NFS 

# nfsstat --rpc
Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
13381      0          0          0          0       

Client rpc stats:
calls      retrans    authrefrsh
0          0          0

Get a List of all NFS Clients 

cat /var/lib/nfs/rmtab

or (from server): 

showmount localhost

unable to register (statd, 1, udp) *RESOLVED*

I was setting up NFS once and I ran into an issue where nfs-kernel-server wouldn't start. Syslog reported this: 

May 19 13:48:56 server rpc.statd[16714]: Version 1.1.2 Starting
May 19 13:48:56 server rpc.statd[16714]: unable to register (statd, 1, udp).

I couldn't figure it out, but was able to resolve it by stopping nfs-common and portmap, and then starting portmap first, verifying it was running with this command: 

# rpcinfo -p localhost
   program vers proto   port
    100000    2   tcp    111  portmapper
    100000    2   udp    111  portmapper

And then starting nfs-common (/etc/init.d/nfs-common start), checking rpcinfo again, and then starting nfs-kernel-server.

NFS Stale File Handle

I'd seen this error in the past, but only when something between the client and the server was disrupted. More recently I saw it happen when the NFS connection was going through a load balancer which made the server believe that only one client was connected. In fact, I'm surprised that worked at all. Even more odd was that after a network re-design, the problem persisted, apparently because the server was running Ubuntu 10 and the client was running Ubuntu 8! Odd, indeed. Another caveat is that the server is running encfs under the NFS mount.

NFS Related Operating Systems

FreeBSD Based

OpenSolaris Based

See Also

Docunext Blog Posts

Links

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