Set Static IP Address on Ubuntu

This comprehensive guide explains how to configure a static IP address on Ubuntu using the netplan configuration system. Setting a static IP is essential for servers, network devices, or any system that requires a consistent network address for reliable connectivity.

Overview

Static IP addresses provide several advantages over dynamic IP assignment:

Consistent Network Identity: Same IP address after reboots and network changes
Server Applications: Essential for hosting services that clients need to find
Network Management: Easier to manage firewall rules and network policies
Remote Access: Reliable SSH and remote desktop connections
Port Forwarding: Stable configuration for router port forwarding rules

Prerequisites

Ubuntu system with network connectivity
Administrative (sudo) privileges
Basic understanding of network concepts (IP, subnet, gateway)
Access to your network's configuration details

Understanding Netplan

Ubuntu uses netplan as the default network configuration system since Ubuntu 18.04. Netplan:

Uses YAML configuration files for network settings
Supports both NetworkManager and systemd-networkd as backends
Provides a unified configuration approach across Ubuntu systems
Validates configuration before applying changes

1. Gather Network Information

Before configuring static IP, collect necessary network information:

1.1 Identify Network Interface

# List all network interfaces
ip link show

# Alternative method
ls /sys/class/net/

Common interface names:

Ethernet: eth0, enp0s3, enp5s0
Wireless: wlan0, wlp2s0
Virtual: vboxnet0, docker0

1.2 Check Current Network Configuration

# Display current IP configuration
ip addr show

# Show routing table
ip route show

# Check DNS configuration
systemd-resolve --status

1.3 Identify Network Details

Gather the following information:

Current IP Address: Your current dynamic IP
Subnet Mask: Typically /24 (255.255.255.0)
Gateway IP: Router's IP address
DNS Servers: Primary and secondary DNS servers

# Find gateway (router IP)
ip route | grep default

# Check DNS servers
cat /etc/resolv.conf

2. Locate Netplan Configuration

2.1 Find Configuration Files

# Navigate to netplan directory
cd /etc/netplan/

# List configuration files
ls -la

Common filenames:

01-netcfg.yaml
00-installer-config.yaml
50-cloud-init.yaml

2.2 Backup Existing Configuration

# Create backup of current configuration
sudo cp /etc/netplan/*.yaml /etc/netplan/backup-$(date +%Y%m%d).yaml

# Alternative: backup entire directory
sudo cp -r /etc/netplan /etc/netplan-backup-$(date +%Y%m%d)

Important Backup Note

Always backup your network configuration before making changes. A misconfigured network can render your system inaccessible remotely.

3. Configure Static IP

3.1 Edit Configuration File

Open the netplan configuration file:

# Replace <filename> with your actual configuration file
sudo nano /etc/netplan/<filename>.yaml

# Example for common filename
sudo nano /etc/netplan/01-netcfg.yaml

3.2 Basic Static IP Configuration

Replace the file contents with a static IP configuration:

network:
  version: 2
  renderer: networkd
  ethernets:
    enp5s0:  # Replace with your interface name
      dhcp4: no
      dhcp6: no
      addresses: [192.168.1.100/24]  # Static IP with subnet mask
      routes:
        - to: default
          via: 192.168.1.1  # Gateway (router) IP
      nameservers:
        addresses: [8.8.8.8, 8.8.4.4]  # DNS servers

3.3 Advanced Configuration Example

For more complex network setups:

network:
  version: 2
  renderer: networkd
  ethernets:
    enp5s0:
      dhcp4: no
      dhcp6: no
      addresses: 
        - 192.168.1.100/24
        - 10.0.0.100/16  # Additional IP address
      routes:
        - to: default
          via: 192.168.1.1
        - to: 10.0.0.0/16
          via: 192.168.1.254  # Specific route
      nameservers:
        addresses: [8.8.8.8, 8.8.4.4, 1.1.1.1]
        search: [local.domain, company.com]  # DNS search domains
      optional: true  # Don't wait for this interface during boot

3.4 Configuration Parameters Explained

Parameter	Description	Example
`dhcp4: no`	Disable IPv4 DHCP	Required for static IP
`dhcp6: no`	Disable IPv6 DHCP	Optional, recommended
`addresses`	Static IP addresses	`[192.168.1.100/24]`
`routes`	Network routing rules	Gateway and specific routes
`nameservers`	DNS server configuration	Public or local DNS servers
`optional`	Interface is optional for boot	`true` or `false`

4. Validate and Apply Configuration

4.1 Validate Configuration Syntax

# Check YAML syntax and netplan configuration
sudo netplan try

# Alternative: generate configuration without applying
sudo netplan generate

The netplan try command:

Applies configuration temporarily
Automatically reverts after 120 seconds if not confirmed
Provides safety against network lockout

4.2 Apply Configuration Permanently

# Apply the configuration permanently
sudo netplan apply

If using netplan try, you'll be prompted to confirm:

Do you want to keep these settings?

Press ENTER before the timeout to accept the new configuration

Changes will revert in 120 seconds

Press ENTER to confirm and make changes permanent.

5. Verify Configuration

5.1 Check IP Address Assignment

# Display current IP addresses
ip addr show

# Check specific interface
ip addr show enp5s0

Expected output should show your static IP:

2: enp5s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
    inet 192.168.1.100/24 brd 192.168.1.255 scope global enp5s0

5.2 Test Network Connectivity

# Test gateway connectivity
ping -c 4 192.168.1.1

# Test internet connectivity
ping -c 4 8.8.8.8

# Test DNS resolution
ping -c 4 google.com

# Check routing table
ip route show

5.3 Verify DNS Configuration

# Check DNS resolution
nslookup google.com

# Alternative DNS test
dig google.com

# Check systemd-resolved status
systemd-resolve --status

6. Troubleshooting

6.1 Common Issues and Solutions

Configuration Not Applied

# Check netplan status
sudo netplan --debug apply

# Check systemd-networkd status
sudo systemctl status systemd-networkd

# Restart networking service
sudo systemctl restart systemd-networkd

YAML Syntax Errors

# Validate YAML syntax
sudo netplan try

# Check for common issues:
# - Incorrect indentation (use spaces, not tabs)
# - Missing colons after keys
# - Improper list formatting

Network Interface Not Found

# List all available interfaces
ip link show

# Check if interface is enabled
sudo ip link set enp5s0 up

# Check kernel messages for hardware issues
dmesg | grep -i network

IP Address Conflicts

# Scan network for IP conflicts
sudo nmap -sn 192.168.1.0/24

# Check ARP table for duplicates
arp -a

# Use different IP address in same subnet

6.2 Revert to DHCP

If you need to revert to automatic IP assignment:

# Edit netplan configuration
sudo nano /etc/netplan/01-netcfg.yaml

Change configuration to:

network:
  version: 2
  renderer: networkd
  ethernets:
    enp5s0:
      dhcp4: yes
      dhcp6: yes

Apply changes:

sudo netplan apply

6.3 Emergency Recovery

If you lose network connectivity:

Physical Access Method:

# Restore from backup
sudo cp /etc/netplan/backup-*.yaml /etc/netplan/01-netcfg.yaml
sudo netplan apply

Single User Mode:
- Boot into recovery mode
- Mount filesystem as read-write
- Edit netplan configuration
- Restart networking

7. Advanced Configurations

7.1 Multiple Network Interfaces

network:
  version: 2
  renderer: networkd
  ethernets:
    enp5s0:  # Primary interface
      dhcp4: no
      addresses: [192.168.1.100/24]
      routes:
        - to: default
          via: 192.168.1.1
      nameservers:
        addresses: [8.8.8.8, 8.8.4.4]
    
    enp6s0:  # Secondary interface
      dhcp4: no
      addresses: [10.0.0.100/24]
      routes:
        - to: 10.0.0.0/8
          via: 10.0.0.1

7.2 VLAN Configuration

network:
  version: 2
  renderer: networkd
  ethernets:
    enp5s0:
      dhcp4: no
      dhcp6: no
  
  vlans:
    vlan100:
      id: 100
      link: enp5s0
      addresses: [192.168.100.10/24]
      routes:
        - to: default
          via: 192.168.100.1

7.3 Bridge Configuration

network:
  version: 2
  renderer: networkd
  ethernets:
    enp5s0:
      dhcp4: no
      dhcp6: no
  
  bridges:
    br0:
      interfaces: [enp5s0]
      dhcp4: no
      addresses: [192.168.1.100/24]
      routes:
        - to: default
          via: 192.168.1.1
      nameservers:
        addresses: [8.8.8.8, 8.8.4.4]

8. Best Practices

8.1 IP Address Planning

Use Private IP Ranges:
- 192.168.0.0/16 (192.168.0.1 - 192.168.255.254)
- 10.0.0.0/8 (10.0.0.1 - 10.255.255.254)
- 172.16.0.0/12 (172.16.0.1 - 172.31.255.254)
Avoid Conflicts:
- Check existing DHCP range
- Document assigned static IPs
- Use higher IP ranges for static assignments
Network Segmentation:
- Separate static IPs by function
- Use different subnets for different services

8.2 Security Considerations

# Disable unused network interfaces
sudo ip link set down <interface_name>

# Configure firewall for static IP
sudo ufw allow from 192.168.1.0/24
sudo ufw deny from 0.0.0.0/0

8.3 Documentation and Monitoring

Document Configuration:
- Keep network diagram updated
- Document IP assignments
- Note configuration changes

Monitor Network Status:

# Create monitoring script
#!/bin/bash
echo "Network Status Check - $(date)"
echo "================================"
ip addr show
echo "================================"
ip route show
echo "================================"
ping -c 1 8.8.8.8 >/dev/null && echo "Internet: OK" || echo "Internet: FAIL"

9. Integration with Other Services

9.1 SSH Server Configuration

For systems with static IP and SSH:

# Edit SSH configuration
sudo nano /etc/ssh/sshd_config

# Add specific interface binding
ListenAddress 192.168.1.100

# Restart SSH service
sudo systemctl restart ssh

9.2 Web Server Configuration

Configure web servers to bind to static IP:

# Apache virtual host
<VirtualHost 192.168.1.100:80>
    ServerName myserver.local
    DocumentRoot /var/www/html
</VirtualHost>

# Nginx server block
server {
    listen 192.168.1.100:80;
    server_name myserver.local;
    root /var/www/html;
}

10. Automation and Scripting

10.1 Automated Configuration Script

#!/bin/bash
# Static IP configuration script

INTERFACE="enp5s0"
STATIC_IP="192.168.1.100/24"
GATEWAY="192.168.1.1"
DNS_SERVERS="8.8.8.8,8.8.4.4"

# Create netplan configuration
cat > /etc/netplan/01-static-ip.yaml << EOF
network:
  version: 2
  renderer: networkd
  ethernets:
    ${INTERFACE}:
      dhcp4: no
      dhcp6: no
      addresses: [${STATIC_IP}]
      routes:
        - to: default
          via: ${GATEWAY}
      nameservers:
        addresses: [${DNS_SERVERS}]
EOF

# Apply configuration
netplan apply

echo "Static IP ${STATIC_IP} configured for ${INTERFACE}"

10.2 Configuration Validation Script

#!/bin/bash
# Network configuration validation

echo "Validating network configuration..."

# Check interface status
if ip link show $INTERFACE &>/dev/null; then
    echo "✓ Interface $INTERFACE exists"
else
    echo "✗ Interface $INTERFACE not found"
    exit 1
fi

# Check IP assignment
if ip addr show $INTERFACE | grep -q "inet $STATIC_IP"; then
    echo "✓ Static IP assigned correctly"
else
    echo "✗ Static IP not assigned"
fi

# Check gateway connectivity
if ping -c 1 $GATEWAY &>/dev/null; then
    echo "✓ Gateway reachable"
else
    echo "✗ Gateway unreachable"
fi

# Check internet connectivity
if ping -c 1 8.8.8.8 &>/dev/null; then
    echo "✓ Internet connectivity"
else
    echo "✗ No internet connectivity"
fi

Resources and References

Pro Tips

Always test configuration with netplan try before permanent application
Keep backup of working configuration files
Document your network setup for future reference
Use consistent IP addressing scheme across your network
Consider using configuration management tools for multiple servers

Security Note

Static IP addresses are more visible on the network. Ensure proper firewall configuration and security hardening for systems with static IPs.

Overview​

Prerequisites​

Understanding Netplan​

1. Gather Network Information​

1.1 Identify Network Interface​

1.2 Check Current Network Configuration​

1.3 Identify Network Details​

2. Locate Netplan Configuration​

2.1 Find Configuration Files​

2.2 Backup Existing Configuration​

3. Configure Static IP​

3.1 Edit Configuration File​

3.2 Basic Static IP Configuration​

3.3 Advanced Configuration Example​

3.4 Configuration Parameters Explained​

4. Validate and Apply Configuration​

4.1 Validate Configuration Syntax​

4.2 Apply Configuration Permanently​

5. Verify Configuration​

5.1 Check IP Address Assignment​

5.2 Test Network Connectivity​

5.3 Verify DNS Configuration​

6. Troubleshooting​

6.1 Common Issues and Solutions​

Configuration Not Applied​

YAML Syntax Errors​

Network Interface Not Found​

IP Address Conflicts​

6.2 Revert to DHCP​

6.3 Emergency Recovery​

7. Advanced Configurations​

7.1 Multiple Network Interfaces​

7.2 VLAN Configuration​

7.3 Bridge Configuration​

8. Best Practices​

8.1 IP Address Planning​

8.2 Security Considerations​

8.3 Documentation and Monitoring​

9. Integration with Other Services​

9.1 SSH Server Configuration​

9.2 Web Server Configuration​

10. Automation and Scripting​

10.1 Automated Configuration Script​

10.2 Configuration Validation Script​

Resources and References​