Hands-on steps to reproduce, observe and fix common NFS connection failures using standard Linux tools. 14.01.2026 | reading time: 3 min A client tries to mount an NFS share and gets silence or an access error; this guide shows concrete commands to reproduce the failure, observe protocol behavior and fix the common causes. Failed Mount, Live Debug Start by reproducing the error on the client and collecting immediate evidence with commands; example session: ``` $ showmount -e nfs-server Export list for nfs-server: /srv/nfs 192.168.1.0/24 $ sudo mount -v nfs-server:/srv/nfs /mnt mount.nfs: access denied by server while mounting nfs-server:/srv/nfs $ rpcinfo -p nfs-server program vers proto port service 100000 2 tcp 111 portmapper 100003 3 tcp 2049 nfs ``` Observe the export list, the exact client error text, and whether RPC services are listening. Step-by-step Repairs Act on what the evidence shows: ssh to the server and verify `/etc/exports`, then run `sudo exportfs -v` and `sudo exportfs -ra`; ensure rpcbind is running with `systemctl status rpcbind` and restart the NFS service with `sudo systemctl restart nfs-server`; check firewall rules and allow NFS (example: `firewall-cmd --add-service=nfs --permanent && firewall-cmd --reload`), then on the client force a version or protocol to test, e.g. `sudo mount -o vers=4,proto=tcp nfs-server:/srv/nfs /mnt`. Tweakables and Edge Cases If problems persist, vary protocol and auth: try `vers=3` or `vers=4`, switch `proto=tcp` vs `udp`, inspect id mapping (`idmapd` for NFSv4) and root squashing in exports (`no_root_squash` vs `root_squash`), review SELinux file contexts on the server for labeled exports, and check whether Kerberos-secured exports require `sec=krb5` mount options. Logs, Traces and Packet Capture When the surface checks fail, collect deeper traces: `journalctl -u nfs-server --no-pager`, `dmesg | tail`, `sudo tcpdump -n -s0 port 2049` to watch RPC calls, `rpcinfo -p` to inspect registered RPC programs, and `nfsstat -c` on the client to summarize client-side RPC and operation counts. Final Fixes and Verification After applying fixes, rerun `showmount -e` from the client, remount the share and run simple I/O tests (create, read, remove files) to validate permissions and performance; if intermittent issues remain, capture a tcpdump during a failing mount and compare behavior when a mount succeeds. Closing Perspective NFS problems usually reduce to one of: exports configuration, RPC visibility, network/firewall rules, or incompatible mount options; follow the evidence, iterate fast, and confirm with small file operations to validate a repair—then deepen knowledge with guided learning and exam preparation at bitsandbytes.academy for CompTIA Linux+ or LPIC-1. Join Bits & Bytes Academy First class LINUX exam preparation. network filesystem troubleshooting infrastructure utilities
