Linux arp Guide

Linux arp Guide

Complete beginner-friendly guide to arp on Linux, covering Arch Linux, CachyOS, and other distributions including ARP table management, MAC address resolution, and network troubleshooting.

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Table of Contents

1. Understanding arp
2. arp Basics
3. ARP Table Management
4. Network Troubleshooting
5. Troubleshooting

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Understanding arp

What is arp?

arp (Address Resolution Protocol) manages ARP table.

Uses:

• View ARP table: See MAC address mappings
• Manage entries: Add/remove ARP entries
• Network troubleshooting: Troubleshoot network
• MAC resolution: Resolve IP to MAC

Why it matters:

• Network debugging: Debug network issues
• MAC addresses: See MAC address mappings
• Network management: Manage network layer

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arp Basics

View ARP Table

Basic usage:

# View ARP table
arp -a

# Shows all ARP entries

Specific Host

Host entry:

# Specific host
arp 192.168.1.1

# Shows entry for IP

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ARP Table Management

Add Entry

Add ARP entry:

# Add static entry
sudo arp -s 192.168.1.1 aa:bb:cc:dd:ee:ff

# -s = set (static entry)

Delete Entry

Remove entry:

# Delete entry
sudo arp -d 192.168.1.1

# -d = delete (removes entry)

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Network Troubleshooting

Clear ARP Cache

Flush cache:

# Clear all entries
sudo ip -s -s neigh flush all

# Or use arp
sudo arp -d -a

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Troubleshooting

arp Not Found

Check installation:

# Check arp
which arp

# Usually in net-tools
# Install if missing
sudo pacman -S net-tools

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Summary

This guide covered arp usage, ARP table management, and network troubleshooting for Arch Linux, CachyOS, and other distributions.

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Next Steps

• ip Guide - Modern network tool
• Networking - Network setup
• arp Documentation: man arp

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This guide covers Arch Linux, CachyOS, and other Linux distributions. For distribution-specific details, refer to your distribution's documentation.