Now that we understand how packets to
192.168.33.11 are routed, we should adjust our previous hypothesis to reflect that the route of
enp0s3 is not correct and is causing our issue.
Essentially, what is happening (and we see this via
tcpdump) is that, when the database server (
192.168.33.12) receives a network packet from the blog server (
192.168.33.11), it arrives on the
enp0s8 device. However, when the database server is sending reply packets (
SYN-ACK) to the web application server, the packets are being sent out via the
enp0s3 device is connected to the
10.0.2.0/24 network, it seems that the packet is being rejected (
RESET) by another system or device on the
10.0.2.0/24 network. Most likely, ...