Posted: Wed Jun 07, 2006 1:41 Post subject: Does DD-WRT support router loopback?
Hi all,
I've been considering the DD-WRT firmare on top of a Linksys WRG45 for quite some time. However, I'm trying to discover if the firmware supports what I can only refer to as router loopback.
Basically, I'd like my router to be providing NAT, and let's say it is assigned a public IP of 203.4.5.6. Let's also say that it is internally assigned an address of 192.168.1.1 and I have my mail server at 192.168.1.201 and thus, I have the router set to use port forwarding from ports 25, 110 and 143 to my mail server's internal IP address.
I wish to configure my laptop to check it's mail at 203.4.5.6. This, of course, always works fom outside the network, but I've found many (most) routers that do NOT support access like this when you are INSIDE the network.
Would DD-WRT enable this? Is there a proper term to describe this functionality?
Is there a proper term to describe this functionality?
I'm not sure if it's the "official" term, but I've generally seen it described as "NAT loopback". The definition on how to implement it using iptables can be found in Section 10 of Rusty Russell's NAT HOWTO
Quote:
but I've found many (most) routers that do NOT support access like this when you are INSIDE the network
Indeed. I had this problem on a Netgear DG834G, but found that it was possible to patch it by editing the iptables configuration manually (the most recent firmware on that router actually fixes the issue). Basically as long as a router is Linux based and gives you telnet/ssh access (and hence the ability to manually tweak the iptables config) it can be made to support NAT loopback properly.
Of course, as Eko's mentioned, this isn't a problem with DD-WRT
