Question
Virtual IP inbound NAT using wrong IP going outbound
Hello All, Following a thread I posted recently related to routing the same firewall is giving me problems with a NAT (fortigate 200B, running v4.0,build0639,120906 (MR3 Patch 10)) I am struggling to find a reason why a server with inbound NAT configured using a VIP (for email to flow inbound) is not going out on the same interface it came in on. My understanding is that if I NAT something inbound then it should use the same external IP on the VIP to go outbound? So if I have set it to use a specific external IP coming inbound on port 12 it should show that IP as its IP if it makes an outbound connection? The email server makes outbound connections to mimecast for sending mail and its locked to a specific IP. I have seen this work fine on other fortigates but this one is showing it as using port 9 going out which shouldn' t happen with a server running on a VIP right? The weird thing is its still accepting connections inbound for RDP/email etc. just fine but I had to use a policy route to force it to use the correct interface to go out to mimecast and when I do this the IP when you telnet the mimecast servers is the correct one that I have set as the external IP on the VIP. Here is the setup: port12 -> internal - this has the VIP on it but when the server goes outbound its using port 9?! The firewall in question does have multiple routes out to the internet but I am getting reports that the internet speed is not great for users but its just doing source IP based ECMP so perhaps its just hitting port 9 a lot since this is the first route to the internet in its routing table?
