This is a bit of a weird one and will take a bit of explaining so bear with me.
We have a VMWare ESXi host in the office. It runs half a dozen VMs that provide various business services.
The host's network is configured so that there's an internal network that all the VMs share. It is separate from the rest of the office outside of the host.
One of the VMs is a pfSense Router Distro. Basically, this VM provides the router and a NAT gateway that connects the internal virtual network to the outer office network.
The host has two management IP addresses - one for the outer office network, and one for the internal virtual network.
pfSense is running an OpenVPN Server, and staff connect to the internal virtual network from home over the internet using the OpenVPN client.
The staff who use the VPN are often NOT on the outer office network. They're usually at home working remotely.
Internal virtual network
pfSense router: 192.168.7.0
ESXi management IP: 192.168.7.3
Outer office network:
ESXi management IP: 192.168.0.3
OpenVPN gateway: 10.0.8.5
Here's the problem:
- When I connect to the network from the Internet via OpenVPN, I cannot ping or communicate with 192.168.7.3.
- I CAN communicate with everything else on the internal virtual network
- Virtual machines on the internal virtual network CAN communicate with 192.168.7.3
I'm confident that OpenVPN is working properly... the firewall is completely opened up and everything else is accessible. There's nothing to specifically deny this one IP address.
I have also tested that pfSense CAN ping the ESXi host on 192.168.7.3.... when it pings using it's network adapter connected to the internal virtual network.
pfSense CANNOT ping the ESXi host on 192.168.7.3 when it pings from the OpenVPN network adapter. pfSense CAN ping everything else on the 192.168.7.0/24 subnet via the OpenVPN network adapter, though.
So my conclusion from all of this, is that there appears to either be a problem with pfSense, or there's a problem with the network configuration on the ESXi host.
Perhaps the issue is that the ESXi host is rejecting connections that come from a separate subnet (the 10.0.8.0/24 subnet that OpenVPN assigns IPs on)? Is there some kind of firewall in ESXi that I don't know about?
Any help would be greatly appreciated.