Travel Routers:
The Ultimate
Plan B for Linux Wifi
Copyright (C) 2013 by Steve Litt, All
rights reserved. Material provided as-is, now warranty, use at your own
risk.
Contents
Wifi compatibility is the toughest Linux compatibility issue for the average
Linux laptop business user. The following, in order of best to worst, are
your three ways of achieving Wifi compatibility on your laptop:
- Built in wifi
- (Hopefully) Linux compatible Wifi USB dongle
- Travel router
Built in wifi is always the best if you can do it. Built in gives you the
best antenna, the most reliable performance, and there's nothing to plug in
or keep track of. Wifi dongles are nice, but sometimes drop connections, get
weird, or break, and it's hard to find a Linux compatible dongle (although
Newegg has several).
A travel router is a small device with an RJ-45 wired Ethernet jack that
also has a Wifi transceiver built in.
Travel routers are bulky and inconvenient, , and as far as I know they make
changing wifi networks (like first using in the hotel, then in a restaurant)
time consuming, but they come with several advantages for the Linux
traveller:
- Wifi reception reliable and completely independent of operating
system.
- Look like a wired connection to your laptop.
- OS-independent configuration (usually http server in the travel
router)
- LEDs tell you whether Wifi is available.
When all else fails, the proper travel router will usually succeed.
When shopping for a travel router whose purpose is to replace or back up
your Linux laptop's built in Wifi, you need certain features:
- Ability to do WEP and WPA encryption in all modes, especially Client mode
- OS independent configuration (usually via an HTTP server within the
travel router)
- Client mode (explained in the modes article)
Absence of any of the three preceding features negates a travel router for
the purposes of Linux road warrior Wifi.
In addition, extra credit goes to travel routers having Visual indication of
an available Wifi transmitter (like an LED), and gigabit Ethernet out its
wired connection with 802.11g/n Wifi. You might as well take advantage of
any 802.11n you encounter on the road.
This document's examples are all performed with my D-Link G730AP travel
router, which in my opinion is an excellent travel router for the purpose
of a Wifi plan B. Your travel router will obviously have different
procedures, but as long as you can configure it from your laptop's wired
Ethernet port, your procedure will be somewhat similar.
My D-Link G730AP travel router shipped with one of these Ethernet cables
that can't be disconnected from an Ethernet port with human hands. I was
forced to push a jeweler's screwdriver between the push-tab and the port
in order to push the push tab close enough to the cable to allow removal,
and of course I had to first push the plug in to the port to free it up.
It would have been handy to have five hands to do this.
Personally, I'm a big fan of testing new cables on an Ethernet port of
some busted equipment before trying it on things you value. Personally,
when I encounter a cable that can't easily be unplugged from the port by
hand, I throw the cable out or return it to the store if I bought the
cable separately. Life's too short to break your equipment, and simply
yanking it will likely break your port. I know because I yanked one before
I learned this.
These days, if I can't unplug an Ethernet cable by hand, I go in a bright
area, force a jewelers screwdriver in to move the tab all the way to the
cable, push in and then pull out. I often have to try ten times. I then
get rid of the cable.
My experience tells me that many of these "snagless" cables which have
plastic completely covering the end of the tab cannot be removed by hand.
In such cases, I've sometimes had success by cutting away all the plastic
or rubber, and converting them to "can snag" cables. I'd rather bust a
cable than my laptop.
Travel routers have different modes. The good ones have three different
modes. They have either a physical switch to designate which mode to work
in, or something in the web app configuration. Mine has a physical switch.
You should get the proper mode designated before doing the rest of the
config (except new password, do that immediately). In order to replace your
laptop's Wifi with a travel router, the mode you need is client mode.
Here are the three common modes:
- Client Mode
- Router Mode
- Access Point Mode
Client Mode
Client mode is what you use if you can't get your laptop's Wifi working,
and the hotel has wifi. You substitute the Travel Router for your laptop's
wifi, and get your networking through your wired Ethernet port:
As you can see, Client Mode is the subject of this document.
Router Mode
This is what you do if your hotel room has only wired Internet, and you
don't want to confine yourself to the length of a cable, or there are
multiple people who need to connect to the Internet. Here's the
architecture:
With Router Mode, your travel Router can be configured as a firewall also.
And, if you have multiple computers sharing the Wifi it transmits, those
computers can talk to each other.
|
DANGER WILL
ROBINSON!
Don't user Router Mode if your Travel Router cannot transmit using
WPA encryption. WEP encryption can be easily cracked by a
knowledgeable person, and is thus a security risk. Also, keep in
mind that the ability of a Travel Router to *receive* WPA encrypted
networking doesn't imply its ability to *transmit* WPA. |
Access Point Mode
This is a lot like Router Mode, but it lacks the ability to route and
firewall. Its purpose is to be used with a wired network that already has
a firewalling router. Here's the architecture:
|
DANGER WILL
ROBINSON!
Don't user Router Mode if your Travel Router cannot transmit using
WPA encryption. WEP encryption can be easily cracked by a
knowledgeable person, and is thus a security risk. Also, keep in
mind that the ability of a Travel Router to *receive* WPA encrypted
networking doesn't imply its ability to *transmit* WPA. |
Before you try to connect your travel router to your laptop, you need the
following information:
- What is the make and model number of your Travel Router?
- Where is the reset button and how long do you need to press it to
reset to factory defaults?
- What is the IP address and subnet mask of your travel router's HTTP
server?
- What is the username with which to connect to the travel router's HTTP
server configuration web app?
- What is the SSID, encryption type (if any), and password (if any) of
the Wifi network you intend to use in setting up your travel router?
Armed with the preceding knowledge, you should be in pretty good shape
when configuring your Travel Router to act as a replacement for your
laptop's wifi. And now a few words of example concerning the preceding
list of prerequisites:
- The make and model number of your travel router is often necessary in
order to look up the necessary information listed earlier in this
article. This is especially true for equipment with the physical magic
button that "does everything for you" (as long as you use Windows). Once
you know your make and model, you're pretty likely to find the information
on the web. I was lucky -- my D-Link G730AP listed all this information
in the booklet that shipped with it. My experience with Wifi appliances,
including Travel Routers, is that although the manufacturer often hides
the fact, most of them have Web-app configuration utilities accessible
at an IP address in the Wifi appliance -- you just have to find it. If
it doesn't have such a web app, I would personally not buy it.
- My D-Link G730AP's reset button is on the back, recessed into a hole
requiring a straightened paper clip to press. This is pretty typical of
most Wifi appliances. I don't know the required press time, so I just
use 45 seconds and it works.
- My D-Link G730AP came from the factory with that the travel router's
HTTP server set to 192.168.0.30, subnet mask 255.255.255.0.
- What is the username with which to connect to the travel router's HTTP
server configuration web app? My D-Link G730AP's configuration web app
came configured with username admin and a blank password. Obviously that
password must be changed fast.
- While tech editing this article, I used my home Wifi with WPA2
encryption.
Most, but not all wired network equipment has autosensing, such that when
connecting two equipment pieces together without using a hub, switch or
router, the connection can be made either with a crossover cable or a
normal cable. If either equipment piece (that's not a hub, switch or
router) doesn't auto sense, you'll need to use a crossover cable. With
equipment made in the latter half of the 00's or later, it's hard to find
equipment that's not autosensing, so in practice you can usually use
normal cables.
There's a huge difference between connecting to the web app config
program in your travel router, as opposed to connecting to the Internet through
your travel router. Connecting to the web app requires you to set
your computer's wired ethernet interface to an address in the same subnet
as the travel router's HTTP server (my travel router defaults to 192.168.0.30).
After the Travel Router is configured, accessing the Internet requires
setting your computer's wired Ethernet interface to be supplied by DHCP.
If you forget this you'll ride the Torment Trolley down the Avenue of
Annoyance.
You're using Linux, so it's unlikely the config utility on the CD that
came with your travel router or the little "Autoconfig" physical button on
the travel router (mine doesn't have one, but some do), will work with
Linux. With Linux, your most likely road to success is to use the web app
on the HTTP server at an IP address within your Travel Router.
Always remember, if you ever shut yourself out of your travel router,
pressing the reset button for a certain number of seconds (start with 60,
and move down if that always works), should put the Travel Router back to
its as-shipped factory configured state.
These instructions are for my D-Link G730AP Travel Router. Yours will
probably be similar, but of course different.
- If you're resetting it to default, use a paperclip to press the reset
button for 40 seconds.
- Flip the mode switch to Client Mode (you might need to do this later
in the config web app on your travel router).
- On your laptop, disable wireless networking to prevent false
diagnostic test results.
- Because the default Travel Router IP address is 192.168.0.30, manually
configure your laptop's wired NIC to use something in its subnet, like
192.168.0.1
- Check that the change "took" with ifconfig eth0. If it's not the
address you just set, down and re-up your laptop's wired network address
until it's at the address you set (in my case 192.168.0.1).
- Browse to http://192.168.0.30. You should be confronted with a small
window asking for a username and password. If not, troubleshoot using
ifconfig and ping and your computer's facilities to change the wired
network's networking properties and bring it up and down.
- Username=admin and Password is blank (this is for my travel router,
your password and username will probably be different,
then click OK. Note that this is
completely dependent on the make and model of your travel router. When
you've correctly entered a username and password, the web application
for configuration should pop up.
- Click the "Run Wizard" button, and a little wizard window should pop
up. Keep nexting through it after completing each screen.
- On the first screen, change the password to something hard, and
something you'll remember, then click Next.
- On the "Set Wireless LAN Connection" screen, click "Site Survey" and
on the secondary screen choose your intended Wifi supplier (probably the
one for your hotel). Then click the "Connect" graphical button on the
secondary screen. If all goes well the secondary screen should vanish
after several seconds or a minute or whatever, and your primary config
screen will have the desired Wifi supplier's SSID and channel. Leave
those as is, and click the Next button.
- On the "Set Encryption" screen, set the encryption to match that of
the hotel's wifi. In my case it's WPA2-PSK. The minute I click that
radio button, a "passphrase" and "confirm passphrase" appear.
- Input the hotel Wifi password twice and click Next. The "Setup
Completed" screen should appear.
- On the "Setup Completed" screen, click the "Restart" graphical button.
- Wait 2 minutes, then click the "Close" button. The login screen
appears again. Username is again admin,
but password is now the password you set during configuration. If you
get both correct, you see the config app again. However, you cannot
connect to anything on the Internet.
- Explore, but do not change, the settings on the various combinations
of tabs and left side buttons. Familiarize yourself with the config.
Change nothing.
- On your laptop , not
the travel router config app, change your wired IP address from Manual
to DHCP, and repeatedly down and up the wired network on the computer
until it gets a new
address. Confirm the new IP address (given to you from DHCP)
with the ifconfig command.
- Verify that you can now browse the Internet. If so, you're done.