How to access wifi router config page when it's in Bridge mode?

Question

I have a TP-LINK wifi router (model TL-WA901ND) configured in Bridge mode plugged into my building's network. How can I access the config page of the router? e.g. I might like to adjust the wireless channel it's using.

There's no spare network port at the back for me to use. I haven't tried disconnecting it and using the single port and a network cable. I'd prefer not to, to avoid disrupting other users, but if that's the only option I'll do it.

I've tried pinging the 254 IP Addresses in my range and then checking each one that replied, but that didn't find it. After pinging them I checked my arp table and the router's MAC address isn't listed.

Answer 1

I presume you have setup your WA901ND as a DHCP client, in which case it may have received some IP address from your building's gateway. Please notice: it may, it need not to. If it has an IP address, issue the following command (you may have to install the program nmap, which is absolutely necessary to solve networking problems):

  nmap -p80 192.168.112.0/24

This assumes that your home network is 192.168.112.0/24, replace it with your real home network. This command will display all pcs listening on port 80, which is where a Web page is served. Some machines will reply: 'port closed', which means they do not have a Web server. The others will reply either port open or port filtered; most likely, the WA910ND will have this port open, so that the output of nmap will narrow down the number of IP addresses you will have to try in your Web Browser.

If this fails, you should try

  nmap -p443 192.168.112.0/24

which does the same thing for the encrypted (SSL) port 443. If your WA910ND is up, has a valid IP and it has a Web Server running, it will be listed in either of these two outputs.

If, after trial and error, you have not located it, it means it has not been dished out a valid IP address. This can happen, if it bridges the mon.wlan0 and eth0 interfaces (if you do not understand this, don't worry, just read on). In this case, your only choice is to disconnect it from the building's wifi, and attach yourself directly with a cable.

Please also notice that you should not change the Wifi channel it is operating on, because this must match the channel of your building's wifi, so you have no freedom there.