garpd

Gratuitous ARP daemon written in Go

A small utility for sending gratuitous ARP requests as per RFC522.

Usage

$ garpd -h

-interface value
  interface name for which to send ARP requests, valid multiple times
-interval duration
  how often to send a gratuitous ARP request (default 15s)

Example

garpd \
  -interface en0 \
  -interface en2 \
  -interface en6 \
  -interval 30s

2021/02/02 14:34:29 using 30s as interval
2021/02/02 14:34:29 garp inf (en0)
2021/02/02 14:34:29 garp inf (en0) sent ARP request for 192.168.2.184
2021/02/02 14:34:29 garp inf (en0) sent 1 ARP requests
2021/02/02 14:34:29 garp inf (en2)
2021/02/02 14:34:29 garp inf (en2) sent 0 ARP requests
2021/02/02 14:34:29 garp inf (en6)
2021/02/02 14:34:29 garp inf (en6) sent 0 ARP requests

The above example sent an ARP request for every interface specified for which an IP address was allocated.

Caveats

• Only works for Unix systems.
• Requires CAP_NET_RAW on linux systems
• Requires root on non-linux systems

Debugging

# tcpdump is your friend
sudo tcpdump -i any -XXn arp