Version supported by server and client

• cat /proc/fs/nfsd/versions -> -2 +3 +4 +4.1 +4.2.
• rpcinfo -p localhost -> lists program, vers, proto, port, service.

• Mounting the root filesystem via NFS (nfsroot)

Mount remote point # mount -t nfs4 <SERVER IP>:/<SOURCE PATH> <TARGET PATH>.

• nfs.conf

1. Add path to directories to share in /etc/exports.
2. Enable systemctl status nfs-server.
3. Ensure port 2049 is open for NFS server.

    # exportfs -v
    /srv        <IP/CIDR>(rw,sync,wdelay,hide,no_subtree_check,sec=sys,secure,no_root_squash,no_all_squash,fsid=0)
    /srv/dir_1  <IP/CIDR>(rw,sync,wdelay,hide,no_subtree_check,sec=sys,secure,no_root_squash,no_all_squash)
    /srv/dir_2  <IP/CIDR>(rw,sync,wdelay,hide,no_subtree_check,sec=sys,secure,no_root_squash,no_all_squash)

    $ showmount -e <IP>
    Export list for <IP>:
    /srv/os_y              <IP/CIDR>
    /srv/os_x              <IP/CIDR>
    /srv                   <IP/CIDR>

• Verify that the paths are being exported exportfs -v.
• Verify open ports rpcinfo -p.
• Verify that the server port is open nc -vz <ip> 2049 or ss -aln.
• Verify domain on client and server nfsidmap -d, however, not necessary if idmapping is disabled.
• Boot up another technical environment that has showmount and other necessary programs installed. For example, the installed client or an OS on USB.
  • Verify that the paths are being exported and are reachable from remote computer showmount -e <SERVER IP>.
  • Verify that the share can be mounted mount.nfs4 -v <SERVER IP>:/path /mnt.
  • Verify that the client has established a connection to the server ss -alp | grep :nfs or ss -ntp | grep 2049.
  • If error Network is unreachable, ensure that the network devices are up, NFTables allows connection to the NFS port, and the client IP is assigned in /etc/exports and server IP is assigned as mount address.
  • If error No such file or directory, ensure that the export paths are correctly requested.

Configuration file idmapd.conf.

Disable if running AUTH_UNIX (AUTH_SYS), or enable if running other security than sec=sys, for example Kerberos.

• If running "sys" then note that the user ID on server on client need to be harmonized. That is, ensure UID and GID are same on server and client. For example:

  • 10000 user group
  • 10001 user #1
  • 10002 user #2

• Why NFSv4 UID mapping breaks with AUTH_UNIX

• idmapd errors about "localdomain", or chown failing on nfs4 mount, with "invalid argument"

archlinux netboot diskless node/system, systemd on NFS (v4) fails, rpc.idmapd -- user212827 -- asked Dec 8 at 16:21

Show all NFS shares: nmap -p 2049 <SERVER IP>

Enable and disable RPC debugging.

rpcdebug -m rpc  -s all   # Set all debug flags for RPC.
rpcdebug -m nfsd -s all   # Set all debug flags for NFS Server.
rpcdebug -m nfs  -s all   # Set all debug flags for NFS client.

rpcdebug -m rpc  -c all   # Clear all debug flags for PRC.
rpcdebug -m nfsd -c all   # Clear all debug flags for NFS Server.
rpcdebug -m nfs  -c all   # Clear all debug flags for NFS client.

Use journalctl -f to view log.

Capture and output error:

• rpc.mountd -d all -F
• rpc.nfsd -d