nmcli - NetworkManager Command Line Interface

1. Introduction to nmcli

1.1 What is nmcli?

nmcli is a command-line client for NetworkManager. It allows users to control NetworkManager and report network status without requiring a graphical interface. It's designed for both interactive use and scripting.

1.2 Key Features

• Complete NetworkManager control from command line
• Script-friendly output formats
• Interactive connection editor mode
• Support for all connection types
• Real-time monitoring capabilities
• Tab completion support
• Works over SSH and in headless environments

1.3 Why Use nmcli?

2. Basic Syntax and Structure

2.1 Command Structure

2.2 Common Options

2.3 Objects

2.4 Command Abbreviations

# These are all equivalent:
nmcli connection show
nmcli con show
nmcli c s

# These are equivalent:
nmcli device status
nmcli dev status
nmcli d s

3. General Operations

3.1 General Status and Information

# Show NetworkManager status
nmcli general status

# Show NetworkManager version
nmcli --version

# Show overall connectivity
nmcli general

# Get system hostname
nmcli general hostname

# Set system hostname
nmcli general hostname new-hostname

3.2 General Status Output

$ nmcli general status
STATE         CONNECTIVITY  WIFI-HW  WIFI     WWAN-HW  WWAN    
connected     full          enabled  enabled  enabled  enabled

3.3 Networking Control

# Check if networking is enabled
nmcli networking

# Enable networking
nmcli networking on

# Disable networking (disconnects all)
nmcli networking off

# Check connectivity
nmcli networking connectivity
# Returns: none, portal, limited, full, unknown

# Force connectivity check
nmcli networking connectivity check

3.4 Radio Management

# Show all radio states
nmcli radio all

# Enable/disable WiFi
nmcli radio wifi on
nmcli radio wifi off

# Enable/disable mobile broadband
nmcli radio wwan on
nmcli radio wwan off

# Enable/disable all radios
nmcli radio all on
nmcli radio all off

4. Device Management

4.1 Device Status

# List all devices
nmcli device status
# or
nmcli device
# or
nmcli d

# Show detailed information about all devices
nmcli device show

# Show specific device details
nmcli device show eth0

# Show in script-friendly format
nmcli -t device status

# Show only specific fields
nmcli -f DEVICE,STATE,CONNECTION device status

4.2 Device Status Output

$ nmcli device status
DEVICE   TYPE      STATE         CONNECTION
eth0     ethernet  connected     Wired connection 1
wlan0    wifi      disconnected  --
lo       loopback  unmanaged     --

4.3 Device Operations

# Connect a device (activates connection)
nmcli device connect eth0

# Disconnect a device
nmcli device disconnect eth0

# Reapply connection settings
nmcli device reapply eth0

# Set device to managed
nmcli device set eth0 managed yes

# Set device to unmanaged
nmcli device set eth0 managed no

# Delete software device (bond, bridge, etc.)
nmcli device delete bond0

4.4 WiFi Operations

# List available WiFi networks
nmcli device wifi list

# Rescan for WiFi networks
nmcli device wifi rescan

# Rescan specific device
nmcli device wifi rescan ifname wlan0

# Connect to WiFi network
nmcli device wifi connect "SSID" password "password"

# Connect to WiFi with specific interface
nmcli device wifi connect "SSID" password "password" ifname wlan0

# Connect to hidden WiFi
nmcli device wifi connect "SSID" password "password" hidden yes

# Show WiFi passwords for saved networks
nmcli -s device wifi show-password

# Show QR code for current WiFi (if supported)
nmcli device wifi show-password

4.5 WiFi List Output

$ nmcli device wifi list
IN-USE  BSSID              SSID            MODE   CHAN  RATE       SIGNAL  BARS  SECURITY
*       00:11:22:33:44:55  MyHomeNetwork   Infra  6     130 Mbit/s  85      ▂▄▆█  WPA2
        00:AA:BB:CC:DD:EE  OfficeWiFi      Infra  11    65 Mbit/s   65      ▂▄▆_  WPA2
        00:99:88:77:66:55  GuestNetwork    Infra  1     54 Mbit/s   45      ▂▄__  WPA2

4.6 Monitoring Devices

# Monitor all device changes (real-time)
nmcli device monitor

# Monitor specific device
nmcli device monitor eth0

# Monitor multiple devices
nmcli device monitor eth0 wlan0

# Press Ctrl+C to stop monitoring

5. Connection Management

5.1 Listing Connections

# Show all connection profiles
nmcli connection show
# or
nmcli con show
# or
nmcli c s

# Show only active connections
nmcli connection show --active

# Show specific connection details
nmcli connection show "Wired connection 1"

# Show with all settings including secrets
nmcli -s connection show "Wired connection 1"

# Script-friendly output
nmcli -t connection show

# Show only specific fields
nmcli -f NAME,UUID,TYPE connection show

5.2 Creating Connections

Ethernet Connection with DHCP

# Basic DHCP connection
nmcli connection add \
    type ethernet \
    con-name "My-DHCP" \
    ifname eth0

# With autoconnect enabled
nmcli connection add \
    type ethernet \
    con-name "My-DHCP" \
    ifname eth0 \
    connection.autoconnect yes

Ethernet Connection with Static IP

# Complete static IP configuration
nmcli connection add \
    type ethernet \
    con-name "My-Static" \
    ifname eth0 \
    ipv4.method manual \
    ipv4.addresses "192.168.1.100/24" \
    ipv4.gateway "192.168.1.1" \
    ipv4.dns "8.8.8.8,8.8.4.4"

# With additional settings
nmcli connection add \
    type ethernet \
    con-name "Server-Static" \
    ifname eth0 \
    ipv4.method manual \
    ipv4.addresses "192.168.1.50/24" \
    ipv4.gateway "192.168.1.1" \
    ipv4.dns "8.8.8.8,8.8.4.4,1.1.1.1" \
    ipv4.dns-search "company.local" \
    connection.autoconnect yes \
    connection.autoconnect-priority 10

WiFi Connection

# WPA2 WiFi connection
nmcli connection add \
    type wifi \
    con-name "Home-WiFi" \
    ifname wlan0 \
    ssid "MyNetwork" \
    wifi-sec.key-mgmt wpa-psk \
    wifi-sec.psk "mypassword"

# Hidden WiFi network
nmcli connection add \
    type wifi \
    con-name "Hidden-WiFi" \
    ifname wlan0 \
    ssid "HiddenSSID" \
    wifi-sec.key-mgmt wpa-psk \
    wifi-sec.psk "password" \
    802-11-wireless.hidden yes

Quick WiFi Connect (creates connection automatically)

# Quick connect (creates connection if needed)
nmcli device wifi connect "SSID" password "password"

# Quick connect on specific interface
nmcli device wifi connect "SSID" password "password" ifname wlan0

5.3 Modifying Connections

Change IP Configuration

# Change to static IP
nmcli connection modify "My-Connection" \
    ipv4.method manual \
    ipv4.addresses "192.168.1.100/24" \
    ipv4.gateway "192.168.1.1" \
    ipv4.dns "8.8.8.8,8.8.4.4"

# Change to DHCP
nmcli connection modify "My-Connection" \
    ipv4.method auto

# Add secondary IP address
nmcli connection modify "My-Connection" \
    +ipv4.addresses "192.168.1.101/24"

# Remove IP address
nmcli connection modify "My-Connection" \
    -ipv4.addresses "192.168.1.101/24"

Modify DNS Settings

# Replace all DNS servers
nmcli connection modify "My-Connection" \
    ipv4.dns "8.8.8.8,8.8.4.4"

# Add additional DNS server
nmcli connection modify "My-Connection" \
    +ipv4.dns "1.1.1.1"

# Remove specific DNS server
nmcli connection modify "My-Connection" \
    -ipv4.dns "8.8.8.8"

# Ignore automatic DNS from DHCP
nmcli connection modify "My-Connection" \
    ipv4.ignore-auto-dns yes

# Set DNS search domains
nmcli connection modify "My-Connection" \
    ipv4.dns-search "company.local,example.com"

Modify Connection Settings

# Change connection name
nmcli connection modify "Old-Name" \
    connection.id "New-Name"

# Set autoconnect
nmcli connection modify "My-Connection" \
    connection.autoconnect yes

# Set autoconnect priority (lower = higher priority)
nmcli connection modify "My-Connection" \
    connection.autoconnect-priority 10

# Bind to specific device
nmcli connection modify "My-Connection" \
    connection.interface-name eth0

# Change MTU
nmcli connection modify "My-Connection" \
    802-3-ethernet.mtu 9000

# Clone MAC address
nmcli connection modify "My-Connection" \
    802-3-ethernet.cloned-mac-address "00:11:22:33:44:55"

WiFi Connection Modifications

# Change WiFi password
nmcli connection modify "WiFi-Connection" \
    wifi-sec.psk "newpassword"

# Change SSID
nmcli connection modify "WiFi-Connection" \
    802-11-wireless.ssid "NewSSID"

# Make WiFi connection hidden
nmcli connection modify "WiFi-Connection" \
    802-11-wireless.hidden yes

5.4 Activating and Deactivating Connections

# Activate (bring up) a connection
nmcli connection up "My-Connection"

# Activate by UUID
nmcli connection up uuid 12345678-1234-1234-1234-123456789abc

# Activate connection on specific device
nmcli connection up "My-Connection" ifname eth0

# Deactivate (bring down) a connection
nmcli connection down "My-Connection"

# Deactivate by UUID
nmcli connection down uuid 12345678-1234-1234-1234-123456789abc

# Reload a connection from disk
nmcli connection reload

# Reload specific connection
nmcli connection reload "My-Connection"

# Load connection from file
nmcli connection load /etc/NetworkManager/system-connections/My-Connection.nmconnection

5.5 Deleting Connections

# Delete a connection
nmcli connection delete "My-Connection"

# Delete by UUID
nmcli connection delete uuid 12345678-1234-1234-1234-123456789abc

# Delete multiple connections
nmcli connection delete "Connection1" "Connection2" "Connection3"

5.6 Cloning Connections

# Clone an existing connection
nmcli connection clone "Original-Connection" "Cloned-Connection"

# Clone and modify
nmcli connection clone "Original" "Clone"
nmcli connection modify "Clone" \
    ipv4.addresses "192.168.1.200/24"

6. Interactive Connection Editor

6.1 Entering Interactive Mode

# Edit existing connection interactively
nmcli connection edit "My-Connection"

# Edit by type (creates new if doesn't exist)
nmcli connection edit type ethernet

# Edit by UUID
nmcli connection edit uuid 12345678-1234-1234-1234-123456789abc

6.2 Interactive Editor Commands

6.3 Interactive Editor Example Session

$ nmcli connection edit type ethernet

===| nmcli interactive connection editor |===

Adding a new '802-3-ethernet' connection

Type 'help' or '?' for available commands.
Type 'describe [<setting>.<prop>]' for detailed property description.

You may edit the following settings: connection, 802-3-ethernet (ethernet), 
802-1x, dcb, ipv4, ipv6, tc, proxy
nmcli> set connection.id My-Static-Connection
nmcli> set connection.interface-name eth0
nmcli> set ipv4.method manual
nmcli> set ipv4.addresses 192.168.1.100/24
nmcli> set ipv4.gateway 192.168.1.1
nmcli> set ipv4.dns 8.8.8.8 8.8.4.4
nmcli> print
...
nmcli> save
Connection 'My-Static-Connection' successfully saved.
nmcli> activate
Connection successfully activated
nmcli> quit

7. Advanced Connection Types

7.1 Bond Configuration

# Create bond interface
nmcli connection add \
    type bond \
    con-name bond0 \
    ifname bond0 \
    bond.options "mode=active-backup,miimon=100"

# Add slave interface 1
nmcli connection add \
    type ethernet \
    con-name bond0-slave1 \
    ifname eth0 \
    master bond0

# Add slave interface 2
nmcli connection add \
    type ethernet \
    con-name bond0-slave2 \
    ifname eth1 \
    master bond0

# Configure IP on bond
nmcli connection modify bond0 \
    ipv4.method manual \
    ipv4.addresses "192.168.1.100/24" \
    ipv4.gateway "192.168.1.1"

# Bring up bond
nmcli connection up bond0
nmcli connection up bond0-slave1
nmcli connection up bond0-slave2

Bond Modes

7.2 Bridge Configuration

# Create bridge interface
nmcli connection add \
    type bridge \
    con-name br0 \
    ifname br0

# Add interface to bridge
nmcli connection add \
    type ethernet \
    con-name br0-slave \
    ifname eth0 \
    master br0

# Configure IP on bridge
nmcli connection modify br0 \
    ipv4.method manual \
    ipv4.addresses "192.168.1.100/24" \
    ipv4.gateway "192.168.1.1"

# Bring up bridge
nmcli connection up br0
nmcli connection up br0-slave

# Advanced bridge options
nmcli connection modify br0 \
    bridge.stp no \
    bridge.forward-delay 0

7.3 VLAN Configuration

# Create VLAN interface
nmcli connection add \
    type vlan \
    con-name vlan100 \
    ifname eth0.100 \
    dev eth0 \
    id 100

# Configure IP on VLAN
nmcli connection modify vlan100 \
    ipv4.method manual \
    ipv4.addresses "192.168.100.10/24"

# Bring up VLAN
nmcli connection up vlan100

# Multiple VLANs on same interface
nmcli connection add type vlan con-name vlan200 ifname eth0.200 dev eth0 id 200
nmcli connection add type vlan con-name vlan300 ifname eth0.300 dev eth0 id 300

7.4 Team Configuration (Alternative to Bonding)

# Create team interface
nmcli connection add \
    type team \
    con-name team0 \
    ifname team0 \
    config '{"runner": {"name": "activebackup"}}'

# Add team slaves
nmcli connection add \
    type ethernet \
    con-name team0-slave1 \
    ifname eth0 \
    master team0

nmcli connection add \
    type ethernet \
    con-name team0-slave2 \
    ifname eth1 \
    master team0

# Configure IP
nmcli connection modify team0 \
    ipv4.method manual \
    ipv4.addresses "192.168.1.100/24"

8. Scripting and Automation

8.1 Script-Friendly Output

# Terse mode (colon-separated values)
nmcli -t device status
# Output: eth0:ethernet:connected:Wired connection 1

# Get specific values
nmcli -g IP4.ADDRESS device show eth0
# Output: 192.168.1.100/24

# Multiple fields
nmcli -g NAME,UUID connection show
# Output: Wired connection 1:uuid-here

# Fields option with terse mode
nmcli -t -f NAME,TYPE,DEVICE connection show

# Mode for machine parsing
nmcli -m tabular connection show

8.2 Exit Codes

8.3 Example Scripts

Network Status Check Script

#!/bin/bash
# network-check.sh - Check network connectivity

# Check if NetworkManager is running
if ! systemctl is-active --quiet NetworkManager; then
    echo "ERROR: NetworkManager is not running"
    exit 1
fi

# Get connectivity status
CONNECTIVITY=$(nmcli -t -f CONNECTIVITY general)

echo "Connectivity: $CONNECTIVITY"

case "$CONNECTIVITY" in
    full)
        echo "✓ Full internet connectivity"
        exit 0
        ;;
    limited|portal)
        echo "⚠ Limited connectivity (captive portal?)"
        exit 1
        ;;
    none)
        echo "✗ No connectivity"
        exit 2
        ;;
    *)
        echo "? Unknown connectivity status"
        exit 3
        ;;
esac

Connection Setup Script

#!/bin/bash
# setup-network.sh - Configure network connection

CONNECTION_NAME="Production-Eth"
INTERFACE="eth0"
IP_ADDRESS="192.168.1.100/24"
GATEWAY="192.168.1.1"
DNS="8.8.8.8,8.8.4.4"

# Check if connection exists
if nmcli connection show "$CONNECTION_NAME" &>/dev/null; then
    echo "Connection exists, modifying..."
    nmcli connection modify "$CONNECTION_NAME" \
        ipv4.method manual \
        ipv4.addresses "$IP_ADDRESS" \
        ipv4.gateway "$GATEWAY" \
        ipv4.dns "$DNS"
else
    echo "Creating new connection..."
    nmcli connection add \
        type ethernet \
        con-name "$CONNECTION_NAME" \
        ifname "$INTERFACE" \
        ipv4.method manual \
        ipv4.addresses "$IP_ADDRESS" \
        ipv4.gateway "$GATEWAY" \
        ipv4.dns "$DNS"
fi

# Activate connection
if nmcli connection up "$CONNECTION_NAME"; then
    echo "✓ Connection activated successfully"
    
    # Verify IP assignment
    IP=$(nmcli -g IP4.ADDRESS device show "$INTERFACE")
    echo "Current IP: $IP"
    
    # Test gateway
    if ping -c 3 -W 2 "$GATEWAY" &>/dev/null; then
        echo "✓ Gateway reachable"
    else
        echo "⚠ Cannot reach gateway"
    fi
else
    echo "✗ Failed to activate connection"
    exit 1
fi

WiFi Auto-Connect Script

#!/bin/bash
# wifi-connect.sh - Connect to preferred WiFi network

PREFERRED_NETWORKS=("HomeWiFi" "OfficeWiFi" "MobileHotspot")

# Rescan for networks
nmcli device wifi rescan

# Try each preferred network
for network in "${PREFERRED_NETWORKS[@]}"; do
    # Check if network is available
    if nmcli -t -f SSID device wifi list | grep -q "^${network}$"; then
        echo "Found network: $network"
        
        # Check if connection profile exists
        if nmcli -t -f NAME connection show | grep -q "^${network}$"; then
            echo "Connecting to $network..."
            if nmcli connection up "$network"; then
                echo "✓ Connected to $network"
                exit 0
            fi
        else
            echo "Connection profile not found for $network"
        fi
    fi
done

echo "✗ No preferred networks found"
exit 1

Connection Monitor Script

#!/bin/bash
# monitor-connection.sh - Monitor and log connection changes

LOG_FILE="/var/log/network-changes.log"

log_message() {
    echo "$(date '+%Y-%m-%d %H:%M:%S') - $1" >> "$LOG_FILE"
}

# Get initial state
PREV_STATE=$(nmcli -t -f STATE general)
log_message "Monitoring started. Initial state: $PREV_STATE"

while true; do
    sleep 5
    
    CURR_STATE=$(nmcli -t -f STATE general)
    
    if [ "$CURR_STATE" != "$PREV_STATE" ]; then
        log_message "State changed: $PREV_STATE -> $CURR_STATE"
        
        # Log active connections
        ACTIVE=$(nmcli -t -f NAME connection show --active)
        log_message "Active connections: $ACTIVE"
        
        PREV_STATE="$CURR_STATE"
    fi
done

8.4 Error Handling in Scripts

#!/bin/bash
# Example with proper error handling

# Enable error handling
set -e  # Exit on error
set -u  # Exit on undefined variable

# Function to handle errors
error_exit() {
    echo "ERROR: $1" >&2
    exit 1
}

# Check if running as root (if needed)
[[ $EUID -eq 0 ]] || error_exit "This script must be run as root"

# Check if NetworkManager is running
systemctl is-active --quiet NetworkManager || \
    error_exit "NetworkManager is not running"

# Try to bring up connection with timeout
if ! nmcli -w 30 connection up "My-Connection"; then
    error_exit "Failed to activate connection"
fi

# Verify connectivity
if ! ping -c 3 8.8.8.8 &>/dev/null; then
    echo "WARNING: No internet connectivity" >&2
fi

echo "SUCCESS: Network configured"
exit 0

9. Advanced Features

9.1 Connection Import and Export

# Export connection to file
# (Note: Use nm-connection-editor GUI for graphical export)
# Via command line, manually copy the file:
sudo cp /etc/NetworkManager/system-connections/My-Connection.nmconnection \
    ~/backup/

# Import VPN connection
nmcli connection import type openvpn file /path/to/config.ovpn

# Import generic connection
nmcli connection load /path/to/connection.nmconnection

# Bulk export
for conn in /etc/NetworkManager/system-connections/*.nmconnection; do
    cp "$conn" ~/network-backup/
done

9.2 Secrets Management

# Show connection with passwords visible
nmcli -s connection show "My-Connection"

# Modify password
nmcli connection modify "WiFi" \
    wifi-sec.psk "newpassword"

# Remove saved password (will prompt when connecting)
nmcli connection modify "WiFi" \
    wifi-sec.psk ""

# Store password in keyring vs connection file
nmcli connection modify "My-Connection" \
    connection.permissions ""

9.3 Dispatcher Scripts

# Example dispatcher script
# File: /etc/NetworkManager/dispatcher.d/10-my-script

#!/bin/bash
# Arguments: $1 = interface, $2 = action

INTERFACE=$1
ACTION=$2

case "$ACTION" in
    up)
        echo "Interface $INTERFACE is up" | logger
        # Run custom commands
        ;;
    down)
        echo "Interface $INTERFACE is down" | logger
        # Run cleanup commands
        ;;
    vpn-up)
        echo "VPN connection established" | logger
        # VPN-specific actions
        ;;
    vpn-down)
        echo "VPN connection closed" | logger
        ;;
esac

exit 0

# Make executable:
# sudo chmod +x /etc/NetworkManager/dispatcher.d/10-my-script

9.4 Static Routes

# Add static route
nmcli connection modify "My-Connection" \
    +ipv4.routes "10.0.0.0/8 192.168.1.254"

# Add route with metric
nmcli connection modify "My-Connection" \
    +ipv4.routes "10.0.0.0/8 192.168.1.254 100"

# Remove route
nmcli connection modify "My-Connection" \
    -ipv4.routes "10.0.0.0/8 192.168.1.254"

# Ignore automatically obtained routes
nmcli connection modify "My-Connection" \
    ipv4.ignore-auto-routes yes

# Never use as default route
nmcli connection modify "My-Connection" \
    ipv4.never-default yes

9.5 Connection Permissions

# Make connection available to specific user
nmcli connection modify "My-Connection" \
    connection.permissions "user:john:;"

# Make available to multiple users
nmcli connection modify "My-Connection" \
    connection.permissions "user:john:;user:jane:;"

# Remove user restrictions (system-wide)
nmcli connection modify "My-Connection" \
    connection.permissions ""

10. Troubleshooting with nmcli

10.1 Diagnostic Commands

# Check overall status
nmcli general status

# Check device status
nmcli device status

# Check active connections
nmcli connection show --active

# Get detailed device info
nmcli device show eth0

# Check logs
journalctl -u NetworkManager -n 50

# Monitor real-time changes
nmcli monitor

# Test connectivity
nmcli networking connectivity check

10.2 Common Issues and Solutions

Issue: Connection Won't Activate

# Check connection details
nmcli connection show "My-Connection"

# Check device state
nmcli device status

# Try bringing device up first
nmcli device connect eth0

# Check for conflicts
nmcli connection show --active

# Deactivate conflicting connection
nmcli connection down "Other-Connection"

# Try with longer timeout
nmcli -w 60 connection up "My-Connection"

# Check logs for errors
journalctl -u NetworkManager -n 100 | grep -i error

Issue: No IP Address Assigned

# Check IP method
nmcli -f ipv4.method connection show "My-Connection"

# Verify DHCP is working (if using auto)
nmcli connection modify "My-Connection" ipv4.method auto
nmcli connection up "My-Connection"

# Check if address is assigned
nmcli -f IP4.ADDRESS device show eth0

# Try manual DHCP request
nmcli device reapply eth0

# Check DHCP logs
journalctl -u NetworkManager | grep -i dhcp

Issue: DNS Not Working

# Check DNS settings
nmcli -f ipv4.dns device show eth0

# Check resolv.conf
cat /etc/resolv.conf

# Set DNS manually
nmcli connection modify "My-Connection" \
    ipv4.dns "8.8.8.8,8.8.4.4"

# Ensure not ignoring auto DNS
nmcli connection modify "My-Connection" \
    ipv4.ignore-auto-dns no

# Restart connection
nmcli connection down "My-Connection"
nmcli connection up "My-Connection"

# Test DNS
nslookup google.com
dig google.com

Issue: Changes Not Persisting

# Ensure connection is saved
nmcli connection modify "My-Connection" connection.id "My-Connection"

# Check connection files exist
ls -l /etc/NetworkManager/system-connections/

# Reload connections from disk
nmcli connection reload

# Check permissions
ls -l /etc/NetworkManager/system-connections/My-Connection.nmconnection
# Should be: -rw------- root root

# Fix permissions if needed
sudo chmod 600 /etc/NetworkManager/system-connections/*.nmconnection
sudo chown root:root /etc/NetworkManager/system-connections/*.nmconnection

10.3 Debug Mode

# Enable debug logging temporarily
sudo nmcli general logging level DEBUG domains ALL

# View debug logs
journalctl -u NetworkManager -f

# Restore normal logging
sudo nmcli general logging level INFO domains ALL

# Or edit config file for persistent debug
sudo vi /etc/NetworkManager/NetworkManager.conf
# Add:
[logging]
level=DEBUG
domains=ALL

# Restart NetworkManager
sudo systemctl restart NetworkManager

11. Best Practices

11.1 Naming Conventions

11.2 Script Best Practices

• Always use -t flag for machine parsing
• Use -g for getting specific values
• Check exit codes in scripts
• Use -w timeout to prevent hanging
• Quote connection names with spaces
• Use -- before connection names starting with -
• Test with -a (ask) mode first for interactive use
• Log all network changes

11.3 Configuration Management

11.4 Security Best Practices

12. Quick Reference

12.1 Most Common Commands

12.2 Command Cheat Sheet

# === GENERAL ===
nmcli general status                    # Overall status
nmcli general hostname                  # Show hostname
nmcli general hostname new-name         # Set hostname

# === NETWORKING ===
nmcli networking on                     # Enable networking
nmcli networking off                    # Disable networking
nmcli networking connectivity           # Check connectivity

# === RADIO ===
nmcli radio wifi                        # WiFi status
nmcli radio wifi on/off                 # WiFi control
nmcli radio all on/off                  # All radios control

# === DEVICES ===
nmcli device                            # List devices
nmcli device show                       # Show device details
nmcli device show eth0                  # Specific device
nmcli device connect eth0               # Connect device
nmcli device disconnect eth0            # Disconnect device
nmcli device wifi list                  # List WiFi networks
nmcli device wifi rescan                # Rescan WiFi
nmcli device monitor                    # Monitor changes

# === CONNECTIONS ===
nmcli connection                        # List connections
nmcli connection show                   # List all
nmcli connection show --active          # Active only
nmcli connection show "Name"            # Details
nmcli connection up "Name"              # Activate
nmcli connection down "Name"            # Deactivate
nmcli connection reload                 # Reload all
nmcli connection delete "Name"          # Delete
nmcli connection clone "Old" "New"      # Clone

# === MODIFY ===
nmcli con mod "Name" ipv4.method auto                        # DHCP
nmcli con mod "Name" ipv4.method manual                      # Static
nmcli con mod "Name" ipv4.addresses "192.168.1.100/24"      # Set IP
nmcli con mod "Name" ipv4.gateway "192.168.1.1"             # Set gateway
nmcli con mod "Name" ipv4.dns "8.8.8.8,8.8.4.4"            # Set DNS
nmcli con mod "Name" +ipv4.dns "1.1.1.1"                    # Add DNS
nmcli con mod "Name" -ipv4.dns "8.8.8.8"                    # Remove DNS
nmcli con mod "Name" connection.autoconnect yes             # Autoconnect

# === CREATE ===
# DHCP Ethernet
nmcli con add type ethernet con-name "Name" ifname eth0

# Static Ethernet
nmcli con add type ethernet con-name "Name" ifname eth0 \
    ipv4.method manual ipv4.addresses "192.168.1.100/24" \
    ipv4.gateway "192.168.1.1" ipv4.dns "8.8.8.8"

# WiFi
nmcli con add type wifi con-name "Name" ifname wlan0 ssid "SSID" \
    wifi-sec.key-mgmt wpa-psk wifi-sec.psk "password"

# === SCRIPTING ===
nmcli -t device status                  # Terse output
nmcli -g IP4.ADDRESS device show eth0   # Get specific value
nmcli -f NAME,TYPE connection show      # Specific fields

12.3 Connection Property Reference

13. Summary