testing fix for nfs shares
This commit is contained in:
Geir Okkenhaug Jerstad
parent
e440585a8c
commit
3f93a85469
3 changed files with 452 additions and 12 deletions
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@ -9,32 +9,89 @@
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../../modules/users/media-group.nix
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];
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# NFSv4 ID mapping for consistent user/group mapping
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services.rpcbind.enable = true;
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services.nfs.idmapd = {
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enable = true;
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settings = {
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General = {
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Domain = "home.lab";
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Verbosity = 0;
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};
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Mapping = {
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Nobody-User = "nobody";
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Nobody-Group = "nogroup";
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};
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};
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};
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# NFS server configuration
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services.nfs.server = {
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enable = true;
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# Increased thread count for better performance
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threads = 16;
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# Export the storage directory (ZFS dataset)
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# Allow access from both local network and Tailscale network
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# Using layered security approach with different permission models
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exports = ''
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/mnt/storage 10.0.0.0/24(rw,sync,no_subtree_check,no_root_squash) 100.64.0.0/10(rw,sync,no_subtree_check,no_root_squash)
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/mnt/storage/media 10.0.0.0/24(rw,sync,no_subtree_check,no_root_squash) 100.64.0.0/10(rw,sync,no_subtree_check,no_root_squash)
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# Main storage - root squashed for security, crossmnt for subdirectories
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/mnt/storage 10.0.0.0/24(rw,sync,no_subtree_check,crossmnt,root_squash) 100.64.0.0/10(rw,sync,no_subtree_check,crossmnt,root_squash)
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# Media directory - accessible to media group, root squashed
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/mnt/storage/media 10.0.0.0/24(rw,sync,no_subtree_check,root_squash) 100.64.0.0/10(rw,sync,no_subtree_check,root_squash)
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# Downloads - all users squashed to media group for simplified permissions
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/mnt/storage/downloads 10.0.0.0/24(rw,sync,no_subtree_check,all_squash,anonuid=993,anongid=993) 100.64.0.0/10(rw,sync,no_subtree_check,all_squash,anonuid=993,anongid=993)
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# Backups - admin access only from specific trusted hosts
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/mnt/storage/backups 10.0.0.0/24(rw,sync,no_subtree_check,root_squash) 100.64.0.0/10(ro,sync,no_subtree_check,root_squash)
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# Shares - public access via media group
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/mnt/storage/shares 10.0.0.0/24(rw,sync,no_subtree_check,all_squash,anonuid=993,anongid=993) 100.64.0.0/10(rw,sync,no_subtree_check,all_squash,anonuid=993,anongid=993)
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'';
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# Create exports on startup
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createMountPoints = true;
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};
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# Ensure the storage subdirectories exist with proper ownership (ZFS dataset is mounted at /mnt/storage)
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# Setting ownership to root:media with group write permissions for shared access
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# Using setgid bit (2xxx) for proper group inheritance on new files/directories
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systemd.tmpfiles.rules = [
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"d /mnt/storage/media 0775 root media -"
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"d /mnt/storage/downloads 0775 root media -"
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"d /mnt/storage/backups 0775 root media -"
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"d /mnt/storage/shares 0775 root media -"
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"d /mnt/storage/media 2775 root media -" # Setgid for group inheritance
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"d /mnt/storage/downloads 2775 media media -" # Owned by media group
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"d /mnt/storage/backups 0750 root root -" # Admin only, restricted access
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"d /mnt/storage/shares 2775 media media -" # Public access via media group
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];
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# Performance tuning for NFS
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boot.kernel.sysctl = {
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# Network buffer optimizations
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"net.core.rmem_max" = 134217728;
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"net.core.wmem_max" = 134217728;
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"net.ipv4.tcp_rmem" = "4096 65536 134217728";
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"net.ipv4.tcp_wmem" = "4096 65536 134217728";
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# NFS-specific optimizations
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"fs.nfs.nlm_tcpport" = 32768;
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"fs.nfs.nlm_udpport" = 32768;
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};
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# Required packages for NFS
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environment.systemPackages = with pkgs; [
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nfs-utils
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];
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# Firewall rules are already configured in network module
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# Firewall configuration for NFS services
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networking.firewall = {
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allowedTCPPorts = [
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111 # portmapper (rpcbind)
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2049 # nfsd
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32768 # lockd
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];
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allowedUDPPorts = [
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111 # portmapper (rpcbind)
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2049 # nfsd
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32768 # lockd
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];
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};
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}
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@ -1,6 +1,8 @@
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{ config, pkgs, ... }:
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{
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config,
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pkgs,
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...
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}: {
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imports = [
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../../../modules/users/media-group.nix
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];
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381
research/nfs.md
Normal file
381
research/nfs.md
Normal file
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@ -0,0 +1,381 @@
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# NFS Best Practices and Troubleshooting Guide
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## Overview
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Network File System (NFS) is a distributed file system protocol that allows remote file access over a network. This document outlines best practices for configuring NFS in a home lab environment, focusing on permission management, security, and performance optimization.
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## Current Configuration Analysis
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### Identified Issues
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1. **Missing User ID Mapping**: The current configuration doesn't ensure consistent UIDs/GIDs between server and clients
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2. **Security Concerns**: Using `no_root_squash` poses security risks
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3. **No ID Mapping Configuration**: NFSv4 ID mapping is not configured
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4. **Missing Export Options**: Several important security and performance options are not set
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## NFS Permission Management Best Practices
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### 1. User and Group ID Consistency
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**Problem**: NFS relies on UID/GID matching between server and clients. If a user has UID 1000 on the server but UID 1001 on the client, permission issues will occur.
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**Solutions**:
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#### Option A: Synchronized UIDs/GIDs (Recommended for Home Lab)
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- Ensure the `media` group has the same GID (993) on all machines
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- Create users with consistent UIDs across all systems
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- Use centralized user management (LDAP/AD) for larger setups
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#### Option B: NFSv4 ID Mapping
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Configure NFSv4 ID mapping to translate between different UID/GID spaces:
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```nix
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# On both server and clients
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services.rpcbind.enable = true;
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services.nfs.idmapd = {
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enable = true;
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settings = {
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General = {
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Domain = "home.lab"; # Same domain on all machines
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Verbosity = 0;
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};
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Mapping = {
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Nobody-User = "nobody";
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Nobody-Group = "nogroup";
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};
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};
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};
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```
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#### Option C: Use all_squash for Public Shares
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For truly shared directories where ownership doesn't matter:
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```nix
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exports = ''
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/mnt/storage/shares 10.0.0.0/24(rw,sync,all_squash,anonuid=993,anongid=993)
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'';
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```
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### 2. Security Best Practices
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#### Root Squashing (Critical)
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**Current Issue**: Using `no_root_squash` allows root on clients to access files as root on the server.
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**Fix**: Use root squashing by default and only disable when absolutely necessary:
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```nix
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exports = ''
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# Default: root_squash is enabled (secure)
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/mnt/storage/media 10.0.0.0/24(rw,sync,no_subtree_check,root_squash)
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# Only for trusted admin workstations
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/mnt/storage/backups 10.0.0.100(rw,sync,no_subtree_check,no_root_squash)
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'';
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```
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#### Port Security
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Always use the `secure` option (enabled by default) to restrict access to privileged ports:
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```nix
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exports = ''
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/mnt/storage/media 10.0.0.0/24(rw,sync,secure,no_subtree_check)
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'';
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```
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#### Client Mount Security
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On client systems, use security options:
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```bash
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# Mount with nosuid to prevent privilege escalation
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mount -t nfs -o nosuid,nodev server:/mnt/storage/media /mnt/media
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# In /etc/fstab
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server:/mnt/storage/media /mnt/media nfs nosuid,nodev,rw,hard,timeo=600 0 0
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```
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### 3. Export Options Explained
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#### Permission and Security Options
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- `root_squash`: Map root UID to anonymous user (default, secure)
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- `no_root_squash`: Allow root access (use carefully)
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- `all_squash`: Map all users to anonymous user
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- `anonuid=N`: Set anonymous user UID
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- `anongid=N`: Set anonymous group GID
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#### Performance Options
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- `sync`: Writes are committed before responding (safer, slower)
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- `async`: Writes may be cached (faster, less safe)
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- `no_wdelay`: Don't delay writes (for small random writes)
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#### Access Control Options
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- `rw`: Read-write access
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- `ro`: Read-only access
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- `secure`: Only accept requests from privileged ports (default)
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- `insecure`: Accept requests from any port
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#### Filesystem Options
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- `no_subtree_check`: Don't verify file is in exported subtree (recommended)
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- `subtree_check`: Verify file location (slight security benefit, performance cost)
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## Recommended NFS Configuration
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### Server Configuration (nfs.nix)
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```nix
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{
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config,
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pkgs,
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...
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}: {
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imports = [
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../../modules/users/media-group.nix
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];
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# NFSv4 ID mapping
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services.rpcbind.enable = true;
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services.nfs.idmapd = {
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enable = true;
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settings = {
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General = {
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Domain = "home.lab";
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Verbosity = 0;
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};
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Mapping = {
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Nobody-User = "nobody";
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Nobody-Group = "nogroup";
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};
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};
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};
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# NFS server configuration
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services.nfs.server = {
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enable = true;
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# Optimized exports with proper security
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exports = ''
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# Main storage - root squashed for security
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/mnt/storage 10.0.0.0/24(rw,sync,no_subtree_check,crossmnt) 100.64.0.0/10(rw,sync,no_subtree_check,crossmnt)
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# Media directory - accessible to media group
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/mnt/storage/media 10.0.0.0/24(rw,sync,no_subtree_check,root_squash) 100.64.0.0/10(rw,sync,no_subtree_check,root_squash)
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# Downloads - squash all users to media group
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/mnt/storage/downloads 10.0.0.0/24(rw,sync,no_subtree_check,all_squash,anonuid=993,anongid=993) 100.64.0.0/10(rw,sync,no_subtree_check,all_squash,anonuid=993,anongid=993)
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# Backups - admin only with root access
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/mnt/storage/backups 10.0.0.100(rw,sync,no_subtree_check,no_root_squash)
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# Public shares - anonymous access
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/mnt/storage/shares 10.0.0.0/24(rw,sync,no_subtree_check,all_squash,anonuid=993,anongid=993) 100.64.0.0/10(ro,sync,no_subtree_check,all_squash)
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'';
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createMountPoints = true;
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};
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# Directory permissions and ownership
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systemd.tmpfiles.rules = [
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# Media group directories
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"d /mnt/storage/media 2775 root media -" # Setgid for group inheritance
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"d /mnt/storage/downloads 2775 media media -" # Owned by media group
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"d /mnt/storage/backups 0750 root root -" # Admin only
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"d /mnt/storage/shares 2775 media media -" # Public access via media group
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];
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# Performance tuning
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boot.kernel.sysctl = {
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# Increase NFS server thread count for better performance
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"fs.nfs.nlm_tcpport" = 32768;
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"fs.nfs.nlm_udpport" = 32768;
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};
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# Required packages
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environment.systemPackages = with pkgs; [
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nfs-utils
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];
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# Firewall configuration
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networking.firewall = {
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allowedTCPPorts = [
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111 # portmapper
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2049 # nfsd
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32768 # lockd
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];
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allowedUDPPorts = [
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111 # portmapper
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2049 # nfsd
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32768 # lockd
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];
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};
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}
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```
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### Client Configuration
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```nix
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# Enable NFS client services
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services.rpcbind.enable = true;
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services.nfs.idmapd = {
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enable = true;
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settings = {
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General = {
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Domain = "home.lab"; # Must match server
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};
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};
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};
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# Example mount in /etc/fstab
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# server:/mnt/storage/media /mnt/media nfs4 rw,hard,timeo=600,retrans=5,_netdev,nosuid 0 0
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```
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## Troubleshooting Common Permission Issues
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### 1. "Permission Denied" Errors
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**Symptoms**: Users cannot access files they should be able to access
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**Diagnosis**:
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```bash
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# Check UID/GID mapping
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id username # On both client and server
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# Check export configuration
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exportfs -v
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# Check mount options
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mount | grep nfs
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# Check file permissions
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ls -la /mnt/storage/media
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```
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**Solutions**:
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- Ensure UID/GID consistency
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- Check export options (root_squash, all_squash)
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- Verify group membership
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- Check directory setgid bit (2xxx permissions)
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### 2. "Operation Not Permitted" for File Operations
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**Symptoms**: Can read files but cannot create/modify/delete
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**Solutions**:
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- Check write permissions in exports (`rw` vs `ro`)
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- Verify directory permissions (need write + execute)
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- Check if filesystem is mounted read-only
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- Ensure no conflicting mount options (`ro`, `nosuid`)
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### 3. Files Created with Wrong Ownership
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**Symptoms**: New files appear with unexpected UID/GID
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**Solutions**:
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- Use setgid bit on directories (`chmod g+s /directory`)
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- Configure all_squash with appropriate anonuid/anongid
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- Set up proper ID mapping
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- Use ACLs for complex permission scenarios
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### 4. Root Access Issues
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**Symptoms**: Root operations fail on NFS mounts
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**Solutions**:
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- Check if `root_squash` is intended behavior
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- Use `no_root_squash` only for trusted admin clients
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- Consider using `sudo` on the NFS server instead
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## Performance Optimization
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### Server Tuning
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```nix
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# Increase NFS daemon threads
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services.nfs.server.threads = 16;
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# Kernel parameters for better NFS performance
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boot.kernel.sysctl = {
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"net.core.rmem_max" = 134217728;
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"net.core.wmem_max" = 134217728;
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"net.ipv4.tcp_rmem" = "4096 65536 134217728";
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"net.ipv4.tcp_wmem" = "4096 65536 134217728";
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};
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```
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### Client Tuning
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```bash
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# Mount with performance options
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mount -t nfs4 -o rsize=1048576,wsize=1048576,hard,timeo=600 server:/path /mount
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```
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## Security Considerations
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### 1. Network Security
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- Use VPN or firewall rules to restrict NFS access
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- Consider NFSv4 with Kerberos for authentication
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- Enable RPC-with-TLS for encryption (Linux 6.5+)
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### 2. File System Security
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- Use minimal necessary permissions
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- Regular security audits of export configurations
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- Monitor NFS access logs
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- Implement backup and recovery procedures
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### 3. Access Control
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```nix
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# Example of layered security approach
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exports = ''
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# Development - developers only, root squashed
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/srv/dev 192.168.1.0/24(rw,sync,root_squash,no_subtree_check)
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# Public - read-only, all users squashed
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/srv/public *(ro,sync,all_squash,no_subtree_check)
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# Admin - restricted to specific hosts, root access
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/srv/admin 192.168.1.10(rw,sync,no_root_squash,no_subtree_check)
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'';
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```
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## Monitoring and Maintenance
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### Server Monitoring
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```bash
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# Check NFS statistics
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cat /proc/net/rpc/nfsd
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# Monitor NFS threads
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cat /proc/fs/nfsd/threads
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# Check exports
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exportfs -v
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# Monitor client connections
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ss -tuln | grep :2049
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```
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### Client Monitoring
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```bash
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# Check mount status
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mount | grep nfs
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# Monitor NFS statistics
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nfsstat -c
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# Check for stale handles
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dmesg | grep -i nfs
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```
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## References
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- [Linux NFS-HOWTO](https://tldp.org/HOWTO/NFS-HOWTO/)
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- [exports(5) Manual Page](https://man7.org/linux/man-pages/man5/exports.5.html)
|
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- [Arch Linux NFS Wiki](https://wiki.archlinux.org/title/NFS)
|
||||
- [NFS Performance Tuning](https://nfs.sourceforge.net/)
|
||||
- [Red Hat NFS Documentation](https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/managing_file_systems/)
|
||||
|
||||
## Conclusion
|
||||
|
||||
Proper NFS configuration requires careful attention to:
|
||||
1. User/group ID consistency
|
||||
2. Appropriate security settings
|
||||
3. Performance optimization
|
||||
4. Regular monitoring and maintenance
|
||||
|
||||
The recommended configuration provides a good balance of security, performance, and usability for a home lab environment. Always test changes in a development environment before applying to production systems.
|
||||
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