Joined: 16 Dec 2012
|Posted: Sun Dec 16, 2012 16:50 Post subject: ASUS RT-N66U does not apply properly the NAT
I have an ASUS RT-N66U with DD-WRT on it (dd-wrt.v24-19519_NEWD-2_K2.6_big_RT-N66U.trx http://www.dd-wrt.com/dd-wrtv2/downloads/others/eko/BrainSlayer-V24-preSP2/2012/07-20-12-r19519/broadcom_K26/dd-wrt.v24-19519_NEWD-2_K2.6_big_RT-N66U.trx ).
I found some routing issues on this release of DD-WRT for N66U. The issue can be reproduced on dd-wrt.v24-18946_NEWD-2_K2.6_big and dd-wrt.v24-19519_NEWD-2_K2.6_big_RT-N66U. I did not tried with other versions, but for sure the problem exists with the ones I already mentioned.
I will provide as much details in order to give you the possibility to reproduce the problem and apply the fix.
INTERNET ---(nat)--- ASUS RT-N66U ---(route)--- PC (act as router) ---(route)--- NETWORK21
WAN IP: 85.XXX.XXX.XXX
Router IP: 192.168.2.1/24
PC network interface #1: 192.168.2.2/24
PC network interface #2: 192.168.21.254/24
The PC is configured as router.
On DD-WRT a route rule has been added to route all traffic for 192.168.21.0/24 to 192.168.2.2 (interface LAN WLAN).
To avoid any possible misconfiguration, the firewall has been deactivated on all the connected machines.
If I connect a second computer to the router (IP: 192.168.2.3/24, GW: 192.168.2.1, DNS: 192.168.2.1) I can ping / communicate with any computer connected to NETWORK21 (192.168.21.0/24). I also can communicate from NETWORK21 with any resource connected to 192.168.2.0/24 network. So, the routing rules are well configured.
The problem is when any resource from NETWORK21 is trying to connect to internet. For example a machine (let’s name it PCINT1) which is connected to NETWORK21 has the following configuration:
So, PCINT1 (192.168.21.2/24) is able to communicate with 192.168.21.254 (the PC who acts as router) and 192.168.2.1 (ASUS RT-N66U), but not able to communicate with any other resource from internet.
The PC who acts as router is able to communicate with any other resource from internet.
It’s like the ASUS RT-N66U does not apply properly the NAT for any other subnet other than 192.168.2.0/24.
If I leave the same configuration but I revert to the ASUS firmware RT-N66U_126.96.36.199_260, the problem does not persists anymore (PCINT1 is able to connect to internet).
I have the same network configuration (only the subnets are different) in another city, but I use DD-WRT v24-sp2 (10/10/09) std with an Linksys WRT54 GL. No problems encountered with that version of DD-WRT!
In case it’s necessary to provide more details, please let me know. DD-WRT is by far the best solution I used and I would like to help to fix this problem.