arp command in Linux
The Linux arp command allows users to view and manipulate the Address Resolution Protocol (ARP) cache and tables. It is a valuable tool for troubleshooting network connectivity issues and managing network configurations. With arp, users can display the ARP cache, add static ARP entries, and delete existing entries. By understanding how to use the ARP command effectively, users can ensure smooth and efficient network communication within their Linux system.
arp Syntax:
Section titled “arp Syntax:”arp [OPTION] [ADDRESS]Linux arp Options:
Section titled “Linux arp Options:”| Option | Description |
|---|---|
| -a, —inet | Display the ARP table for IPv4 addresses |
| -A, —addr | Display the ARP table for all network addresses |
| -n, —numeric | Show numerical addresses instead of resolving hostnames |
| -d, —delete | Delete an entry specified by ADDRESS |
| -v, —verbose | Display detailed information |
| -i, —device | Specify the network interface to operate on |
| -s, —set | Create a new entry for the specified ADDRESS |
arp Parameters:
Section titled “arp Parameters:”| Parameter | Description |
|---|---|
| ADDRESS | Specifies the target network address |
How to use arp command:
Section titled “How to use arp command:”Display ARP Table
Section titled “Display ARP Table”arpDisplays the ARP table showing the IP and MAC addresses of devices connected to the network.
Display ARP Table for a Specific Interface
Section titled “Display ARP Table for a Specific Interface”arp -i eth0Displays the ARP table for a specific network interface, such as eth0.
Clear ARP Cache
Section titled “Clear ARP Cache”sudo arp -d 192.168.1.1Clears the ARP cache entry for the specified IP address “192.168.1.1”.
Resolve MAC Address from IP Address
Section titled “Resolve MAC Address from IP Address”arp 192.168.1.1Resolves and displays the MAC address corresponding to the IP address “192.168.1.1”.
Add a Static ARP Entry
Section titled “Add a Static ARP Entry”sudo arp -s 192.168.1.2 00:11:22:33:44:55Adds a static ARP entry mapping IP address “192.168.1.2” to MAC address “00:11:22:33:44:55”.
Delete a Static ARP Entry
Section titled “Delete a Static ARP Entry”sudo arp -d 192.168.1.2Deletes the static ARP entry for the specified IP address “192.168.1.2”.
Display ARP Table with Numeric Values
Section titled “Display ARP Table with Numeric Values”arp -nDisplays the ARP table with numeric values (IP and MAC addresses) without resolving hostnames.
Display ARP Cache Information
Section titled “Display ARP Cache Information”arp -vDisplays additional information about the ARP cache entries such as age and hardware type.
How do I use arp in Linux?
Section titled “How do I use arp in Linux?”To use the arp command in Linux, execute the following command:
arpHow do I display the ARP cache in Linux?
Section titled “How do I display the ARP cache in Linux?”To display the ARP cache in Linux, use the following command:
arp -nHow do I add an entry to the ARP cache in Linux?
Section titled “How do I add an entry to the ARP cache in Linux?”To add an entry to the ARP cache in Linux, you can use the following command format:
arp -s <IP_address> <MAC_address>How do I delete an entry from the ARP cache in Linux?
Section titled “How do I delete an entry from the ARP cache in Linux?”To delete an entry from the ARP cache in Linux, use the following command:
arp -d <IP_address>How do I flush the ARP cache in Linux?
Section titled “How do I flush the ARP cache in Linux?”To flush the ARP cache in Linux, you can use the following command:
ip -s -s neigh flush allHow do I set a specific timeout for ARP cache entries in Linux?
Section titled “How do I set a specific timeout for ARP cache entries in Linux?”To set a specific timeout for ARP cache entries in Linux, execute the following command:
echo "600" > /proc/sys/net/ipv4/neigh/default/gc_stale_timeHow do I prevent ARP cache poisoning in Linux?
Section titled “How do I prevent ARP cache poisoning in Linux?”To prevent ARP cache poisoning in Linux, you can enable ARP inspection on your network switches and use tools like arpwatch to monitor ARP activities.
How do I view detailed information about an IP in the ARP cache in Linux?
Section titled “How do I view detailed information about an IP in the ARP cache in Linux?”To view detailed information about an IP in the ARP cache in Linux, you can use the following command:
arp -a <IP_address>Applications of the arp Command
Section titled “Applications of the arp Command”- Display and modify the IP-to-MAC address translation tables
- View the ARP cache
- Debug networking issues related to ARP
- Spoofing attacks detection and prevention
- Troubleshoot connectivity problems