I've upgraded my network, and I want to use the old router as a print server because it supports that feature.

However, if I'm going to do this, I need to disable all the LAN ports on the router to prevent security flaws.

Basically, I don't want some smartarse to bypass the firewall by plugging into the router, because I have the printers on a different subnet than the wireless clients.

I have tried for a week with different firmwares and messing with nvram and ifconfig through SSH, but I have had no luck.

Either nothing happens when I reboot the router after making changes, or I also disable the WAN in the process, and I need that for it to function as a print server.

Shouldn't there just be a simple way to tell the router to look only for the WAN hardware when starting up? Will editing something in dnsmasq.conf to force self-assigned IP's work?

I'd really rather not glue the ports in case I decide to use it for something else in the future. Does anyone have any ideas how to go about disabling the LAN?

  • I'd load Tomato onto it and then put the physical ports into unusued VLANs. That way if they do plug in to it, they're not going to have a useful connection. Jan 30, 2015 at 0:46
  • On second thoughts looks like the RT-N56U does not support tomato because of its chipset. forums.smallnetbuilder.com/showthread.php?t=6810&page=3 Jan 30, 2015 at 0:48
  • Why can't you put the old router on the inside of the firewall? That then gives you extra switchports.
    – Paul
    Jan 30, 2015 at 1:17
  • Secured cupboard/server area, and or business class router (for example, the ones we use make it quite obvious how to disable ports). Jan 30, 2015 at 4:46
  • I cannot put the router on a firewall because of the way that the printer subnet is configured. The printers are on a different vlan and a different physical switch than the Wireless AP's that I use for easy configuration. It would be much easier to disable the LAN ports on the print server than to jack around with the network configuration that's already working the way I want it to.
    – ekrekeler
    Jan 30, 2015 at 16:32

1 Answer 1


If your wireless clients are known, you could use MAC filtering on the router so that any unknowns would not have network access via WLAN or LAN.

  • I don't want any clients to connect. So is there a way to configure that via SSH? The WebUI doesn't have that option.
    – ekrekeler
    Jan 30, 2015 at 17:38
  • You don't want any wired or wireless clients to connect whatsoever? Also, what firmware are you running currently?
    – astv25
    Jan 31, 2015 at 4:55
  • That is correct. I am only using it as a USB print server. I am currently running the Aria build Padavan's custom firmware for the RT-N56U, but if needed I can load ASUSWRT on it again. Tomato and DD-WRT are not supported.
    – ekrekeler
    Jan 31, 2015 at 18:02

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