ICMP reply from the firewall instead of endpoint destination

cancel
Showing results for 
Search instead for 
Did you mean: 

ICMP reply from the firewall instead of endpoint destination

L1 Bithead

Hello everybody,


What could cause ping to respond from a different IP?
When tested from source, the response message of the ping command is successful and it's coming from the PaloAlto firewall, not from the destination IP.
Where and how can I verify on the PaloAlto if this is expected or not?
What setup can cause such behavior on the PaloAlto?
Need to mention that the destination is RPC server to which the source can't connect, even though there is sucessful ICMP reply from the PaloAlto firewall. 
Source and destinaiton are on different networks.

Thanks!

1 ACCEPTED SOLUTION

Accepted Solutions

Cyber Elite
Cyber Elite

Incorrect implementation of NAT could cause the firewall to assume 'ownership' of IP addresses through proxy-arp

This typically happens if the destination in a NAT policy is set to a subnet

Tom Piens
PANgurus

View solution in original post

2 REPLIES 2

Cyber Elite
Cyber Elite

Incorrect implementation of NAT could cause the firewall to assume 'ownership' of IP addresses through proxy-arp

This typically happens if the destination in a NAT policy is set to a subnet

Tom Piens
PANgurus

Indeed, it was found that there is a NAT which causes the reply from the firewall. 
The traffic in question only returns through the firewall and hits NAT rule on it's way back.
However that traffic does not go through the firewall on it's way out.
ICMP is not affected by it, but any TCP will be dropped because breaks the 3-way handshake.

Like what you see?

Show your appreciation!

Click Like if a post is helpful to you or if you just want to show your support.

Click Accept as Solution to acknowledge that the answer to your question has been provided.

The button appears next to the replies on topics you’ve started. The member who gave the solution and all future visitors to this topic will appreciate it!

These simple actions take just seconds of your time, but go a long way in showing appreciation for community members and the LIVEcommunity as a whole!

The LIVEcommunity thanks you for your participation!