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Overview

This guide covers network configuration for Arch Linux using dhcpcd for DHCP client functionality and systemd-resolved for DNS resolution.

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DHCP Configuration (dhcpcd)

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Installation

sudo pacman -S dhcpcd
Enable and start the service: 
sudo systemctl enable dhcpcd
sudo systemctl start dhcpcd

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Configuration File

The dhcpcd configuration is located at /etc/dhcpcd.conf.

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Key Settings

Client Identification Use DUID (DHCP Unique Identifier) for client identification: 
duid
Alternatively, use the hardware address: 
#clientid
Some non-RFC compliant DHCP servers may not respond when using DUID. If you experience connection issues, comment out duid and enable clientid instead.
Persistent Configuration Maintain interface configuration when dhcpcd exits: 
persistent
Vendor Class ID Set to blank to avoid sending system information: 
vendorclassid

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DHCP Options

Requested Options Specify which options to request from the DHCP server: 
option domain_name_servers, domain_name, domain_search
option classless_static_routes
option interface_mtu
option host_name
Key options:
  • domain_name_servers - DNS server addresses
  • domain_name - Domain name
  • domain_search - DNS search domains
  • classless_static_routes - Static routing information
  • interface_mtu - Network MTU settings
  • host_name - Request hostname from network
Optional Features 
option rapid_commit
Enables rapid commit support for faster DHCP negotiation (requires server support). Server Identifier Requirement 
require dhcp_server_identifier
Required by RFC2131 to ensure DHCP responses are from legitimate servers.

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IPv6 Configuration

SLAAC (Stateless Address Autoconfiguration) Generate stable private IPv6 addresses: 
slaac private
Alternatively, use hardware address: 
#slaac hwaddr
Disable IPv4 Link-Local 
noipv4ll
Prevents automatic assignment of 169.254.x.x addresses.

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DNS Resolution Hook

Disable dhcpcd’s automatic resolv.conf management: 
nohook resolv.conf
This allows systemd-resolved to manage DNS configuration instead.

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DNS Configuration (systemd-resolved)

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Installation and Setup

systemd-resolved is typically pre-installed on Arch Linux. Enable and start the service: 
sudo systemctl enable systemd-resolved
sudo systemctl start systemd-resolved
Link the stub resolver to /etc/resolv.conf: 
sudo ln -sf /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf
This will overwrite your existing /etc/resolv.conf. Back up any custom DNS configurations before proceeding.

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DNS Stub Listener

The systemd-resolved stub listener provides DNS resolution at: 
nameserver 127.0.0.53
This is configured in /etc/resolv.conf (symlinked to /run/systemd/resolve/stub-resolv.conf): 
nameserver 127.0.0.53
options edns0 trust-ad
search .
Options:
  • edns0 - Enable DNS Extension Mechanisms
  • trust-ad - Trust DNSSEC authenticated data

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Check DNS Status

View current DNS configuration and upstream servers: 
resolvectl status
Query DNS for a specific domain: 
resolvectl query example.com
View DNS statistics: 
resolvectl statistics

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Manual DNS Configuration

To set custom DNS servers for a specific interface: 
sudo resolvectl dns <interface> 1.1.1.1 8.8.8.8
To set DNS search domains: 
sudo resolvectl domain <interface> example.com

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Hosts File

The /etc/hosts file provides static hostname-to-IP mappings.

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Basic Configuration

127.0.0.1         localhost
127.0.0.1         localhost.localdomain
127.0.1.1         linux
::1               localhost
::1               ip6-localhost
::1               ip6-loopback

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IPv6 Addresses

ff00::0           ip6-localnet
ff00::0           ip6-mcastprefix
ff02::1           ip6-allnodes
ff02::2           ip6-allrouters
ff02::3           ip6-allhosts
fe80::1%lo0       localhost

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Broadcast Address

255.255.255.255   broadcasthost

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Ad Blocking with Hosts File

The example configuration uses Steven Black’s unified hosts file for blocking ads, fake news, gambling, porn, and social media: 
curl -o /tmp/hosts https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts
sudo cp /tmp/hosts /etc/hosts
Project: StevenBlack/hosts
Modifying /etc/hosts with large blocklists can impact DNS lookup performance. Test thoroughly before deploying.

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Network Testing

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Check Interface Status

ip addr show
ip link show

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Test Connectivity

ping -c 4 8.8.8.8           # Test IPv4 connectivity
ping -c 4 archlinux.org     # Test DNS resolution

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View DHCP Leases

cat /var/lib/dhcpcd/*.lease

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Monitor Network Traffic

sudo journalctl -u dhcpcd -f
sudo journalctl -u systemd-resolved -f

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Troubleshooting

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No Network Connection

  1. Check interface status: 
    ip link show
  2. Ensure dhcpcd is running: 
    sudo systemctl status dhcpcd
  3. Restart networking: 
    sudo systemctl restart dhcpcd

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DNS Resolution Fails

  1. Check systemd-resolved status: 
    resolvectl status
  2. Verify /etc/resolv.conf symlink: 
    ls -l /etc/resolv.conf
  3. Restart systemd-resolved: 
    sudo systemctl restart systemd-resolved

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Interface Not Getting IP Address

Manually request a new lease: 
sudo dhcpcd -n <interface>
Release and renew: 
sudo dhcpcd -k <interface>  # Release
sudo dhcpcd -n <interface>  # Renew

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File Locations

  • dhcpcd configuration: /etc/dhcpcd.conf
  • DNS configuration: /etc/resolv.conf → /run/systemd/resolve/stub-resolv.conf
  • Hosts file: /etc/hosts
  • DHCP leases: /var/lib/dhcpcd/*.lease

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Additional Resources

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