PIX 515e and Proxy Arp Questions/Issue

uhl_frederick · ‎02-12-2009

Hello, Have a PIX 515E with a subnet connected to the DMZ port. All servers on the DMZ port, lets say 192.168.1.0/24 network have arp entries to any server on the 192.168.1.0 network with the MAC of the PIX port.

Does this mean that and intra-server communication is essentially "routing" via the PIX as the servers only know the layer 2 mac to get to the IP address of the other servers is via the PIX MAC address, which I am guessing does something to the packet and sends it back to the subnet to the destination server?

If so, my ISA server does not like this as it will not reply to pings from servers on the same subnet, but if I put a static ARP entry in the originating server, ping works fine.

And finally, is there a way to turn off PROXY ARP for addressed on the local subnet, but not turn it off completely??

Thanks

Gene

Yudong Wu · ‎02-12-2009

Not sure what version you are using.

There is an explanation here.

http://www.ciscotaccc.com/kaidara-advisor/security/showcase?case=K33183025

You can turn it off by "sysopt noproxyarp < interface_name >"

uhl_frederick · ‎02-12-2009

Thanks for the link. It pretty much explains the issue I am having. In the upgraded versions of software do you know how this is resolved?? (before I just flip the switch and turn it off)

Thanks

Gene

Yudong Wu · ‎02-12-2009

Sorry, I am not sure how and in which version it is fixed.

In version 7.x and above, pix should only do proxy arp to NATed global address. HTH