I use tun/tap to create a tun NIC
tun0 with IP 10.10.10.2,
and I have a real NIC
eth0 with IP 220.127.116.11
then I run a tcp client which binds its socket to 18.104.22.168 and a tcp server binding 10.10.10.2. but I can't establish a tcp connection between them.
so can a tcp client on one NIC connect to a tcp server on the other NIC?