Initially, I have HAVP configured proxy mode as transparent and it works however HAVP has caused some issues for internal network (e.g. I wasn't able to get to certain devices that have built-in http server in LAN). So, I changed proxy mode to internal and proxy interface to loopback (for good measure) then created new the following NAT rule:
destination port: 80
Redirect IP: 127.0.0.1
Redirect port: 3125
NAT Reflection: Use system default
And had it create associate filter rule. In theory, that should work but it doesn't. I wanted to make sure it works before I specify additional parameters to NAT rule not to redirect to HAVP if destination IP is within LAN IP range. I just kept on getting HAVP invalid request page with this basic NAT rule. What am I missing?
I have a workaround which involves modifying havp.inc - I know it will get overwritten when I reinstall HAVP package. I wasn't able to get internal and NAT rules to work so I modified the rule / filter using supernetting so it will not redirect to HAVP if destination IP falls within the IP range.
If anyone has gotten internal and NAT rules to work, please let me know.