guys I have this kind of situation:
I have two routers, R1 is Dlink DIR-100
and R2 is Cisco 877W
R1 is connected to the internet throught its WAN interface.
R2 is connected to the LAN port of R1 in DMZ mode. NAT is ON.
Everything else (computers, laptops) are connected to the R2.
I have configured port forwarding on R2 router so I can use any service I want (like remote desktop) on any machine behind R2, it's working well, but I can't connect directly to R2 router from internet. I'm trying to log to it by telnet and this is what I get in the active session logs of R1 router:
Protocol Source IP Source Port Dest IP Dest Port Age Time
TCP 192.168.1.2 53991 192.168.1.2 23 139
TCP 192.168.1.2 23 192.168.1.2 53991 139
192.168.1.2 is an interface of R2 router connected to the R1 in DMZ mode.
Seems like R2 interface is trying to respond to itself rather than to public IP address of the source.