asked on

Need to build RARP Packet to resolve an IP

I have a task that requires me to receive a RARP request with MAC address and then to send out a RARP Response mapping that MAC to an IP. I understand the concepts behind RARP but am simply having an issue finding examples for building RARP packets in C#. I was wondering if anybody can point me in the right direction for building the actual packet.

David Favor

Likely something like this...

# show all your IPs in ARP cache
arp -n

# grep for some specific MAC address
arp -n | grep $mac

Open in new window

noci

Check out the net-tools package: http://net-tools.sourceforge.net/

Here is some C example code from it:
https://github.com/ecki/net-tools/blob/master/rarp.c

And the example i could find quickest for building a socket based tool for arp.
https://stackoverflow.com/questions/16710040/arp-request-and-reply-using-c-socket-programming

ARP & RARP are related and use the same packet structure.

David Johnson, CD

you do know that RARP is obsolete about the only product that I know of that uses it is Cisco's Overlay Transport Virtualization to update level 2 routing when a mac address moves to between datacenters

noci

There are some devices that use RARP as a kind of poor-mans BOOTP... (like ancient DHCP).

Kevin Dunning

ASKER

Yes I am aware that it is an obsolete Protocol and that there are very few systems that still use it. I'd imagine this is the reason that I am having issues finding examples as a jumping point. Unfortunately the task I am working requires me to respond to a RARP request in C#.

David Johnson, CD

the ietf has the definitive rules for RARP https://tools.ietf.org/html/rfc903

noci

I gave links to RARP tools in C (you should be able to read that and transform it to C#).
Or work from the specs (ietf RFC 903)

This question needs an answer!

Become an EE member today

7 DAY FREE TRIAL

Members can start a 7-Day Free trial then enjoy unlimited access to the platform.

View membership options

Learn why we charge membership fees

We get it - no one likes a content blocker. Take one extra minute and find out why we block content.