Proxy ARP on a Cisco PIX

esupport · ‎10-12-2007

How can I tell what a PIX is going to Proxy ARP for. Is there a command I can use to easily determine this, or do I need to look through the config and manually work out what the PIX will Proxy ARP for? Thanks.

didyap · ‎10-18-2007

Proxy arp allows the pix to respond to arp requests for hosts behind it. So when an arp request is made for an outside host, the pix will respond with it's own mac-address, receive the IP packets and forward them on to the host. Without proxy arp outside hosts would not be able to reach the inside server and vice versa. In a nutshell PIX will proxy arp for all packets that will come to one of its interfaces and leave from the other interface.

Collin Clark · ‎10-18-2007

If you wanted to look for proxy-arp in the config, look for "sysopt noproxyarp outside". The default is no sysopt noproxyarp outside so if it is not in the config it is off.

HTH and please rate.