Hi have the following setup
HostA ---------- Ouside ASA Inside ----------- HostB
IPs
HostA: 172.16.10.2 255.255.0.0
ASA outside interface: 172.16.10.1 255.255.255.0
ASA inside interface: 172.16.20.1 255.255.255.0
HostB: 172.16.20.2
I have access lists on the outside and inside interfaces,
permit ip any any
permit icmp any any
I have a web server running on both the hosts. Neither hosts are configured with a default gateway.
From what I understand, If host A attempt to browse to host B as Host A is in a 255.255.0.0 network it thinks that host B is in the same subnet so sends out an ARP request. The ASA by default should perform a proxy ARP and pass the traffic to Host B.
The Lab I have setup is not working. Anyone got any ideas? Have I got the theory correct?
sysopt noproxy arp is not enabled on any interfaces.
No from what I understand, If hos
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hi lrmoore.
I fixed up the firewall with a static and host b with a default gateway and sure enough it worked.
Now host A can access the web server on Host B. Host B cant access the web server on Host A.
If you have time can you elaborate on the following questions.
Why Cant host B access Host A?
Why does it require a static nat to work?
Thanks, appreciate your assistance.
"So the only question I have is why does it require a static nat to work?"
Because any time you pass traffic between two interfaces, the ASA has to know what address you want it to be translated to on the other side. I understand what you are getting at with the proxy ARP, but as already stated, you still have to translate your traffic from one interface to another in some form or fashion. Then, ARP broadcasts what you nat'd to.
For example, if you had 192.168.1.1 statically translated to 10.9.0.1, the 10.9 address would be the address broadcasted. Alternative you could do a 1 for 1 static translation of the same IP 192.168.1.1, and that's the IP ARP would broadcast.
So short answer, because the NAT translation is just one piece that proxy ARP requires to work.
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by: lrmoorePosted on 2009-10-29 at 18:57:57ID: 25699731
>Neither hosts are configured with a default gateway
Host B absolutely, positively must have a default gateway of 172.16.20.1
There is no other way around it
Proxyarp does not have any play unless you also have a static nat for the inside host to an outside address