[GTALUG] teksavvy dsl 2 modem that runs OpenWRT

[Alex Volkov]

I thought I'd add a follow up to my to how I ended up to the whole story.
(I'll try not to rant)

In short, Raspberry Pi works as a router (hardware-wise is a massive
overkill) but not worth setting up as a residential access point, because
of the following issues that cropped up:

0 Raspberry Pi Ethernet port is auto-sensing, no need for crossover cables.
That bit helped me to retain my sanity.

1. Raspberry Pi doesn't come with built-in wireless card, so there are no
wireless drivers shipped with OS image (which is only 76MB in size) --
http://wiki.openwrt.org/toh/raspberry_pi . You will have to figure out
yourself where to find drivers and then manually resolve dependencies. opkg
(OpenWrt package manager) helps, but there's still a lot of work that has
to be done manually.

2. Serial port works, in the usual raspberry pi configuration --
http://www.adafruit.com/product/954, however login console is not
configured, so all yo can see there are the boot messages. You can't access
the Internet using ethernet as WAN interface and configure everything
through serial console.

2. Having only one ethernet port means that you can't connect to the
Internet through Raspberry Pi in order to configure wireless; you have to
configure wireless before you can use the only ethernet port as a WAN
interface.

I found this protocol helps having internet connection through host
wireless interface and ssh access to a raspberry pi through ethernet:
    * Connect to wireless
    * /sbin/route -a | grep default (write down IP address from the second
column -- Gateway)
    * Connect to Raspberry Pi ethernet port
    * /sbin/route del default gw
    * /sbin/route add default gw <value from step 2>
At this point you should be able to access the Internet and Raspberry Pi at
the same time.


4. Once you get wireless working now you can assign WAN to ethernet
interface, you have to be careful, if something goes wrong at that stage,
there's no undoing it, and  you have to start from the beginning.
At this point command 'dd if=/dev/mmcblk0 of=owrt_bak.img bs=1M count=80'
becomes really useful. Also if you need to customize your subnet address do
it before configuring wireless.

5. There's no assignment of network devices for wireless cards in Barrier
Breaker, so most of the knowledge you have from configuring low-level
wireless  on Linux is no longer applicable to OpenWRT, however dmesg and iw
are still around.
OpenWrt uses radio0...radionN wlan.config settings, that could later be
assigned a particular interface if needed; however the card I was
using(tl-wn722n) had 3 radioN interfaces, of which only one (radio2) was
actual hardware that was doing something, which could be very confusing.

6. Host AP/Encryption packaging has become a mess, there are three
alternative systems (hostapd, wpa_supplicant and wpad). I ended up using
wpad, however package hostapd-common was still required.

As I mentioned I used TL-WN722N(ath9k_htc), usb dongle. It's not fast or
compact, but is very linux-friendly. Works flawlessly in AP mode. Here are
the packages required to get the wireless and this card going.

hostapd-common
iw
kmod-ath
kmod-ath9k-common
kmod-ath9k-htc
kmod-cfg80211
kmod-crypto-aes
kmod-crypto-arc4
kmod-crypto-core
kmod-mac80211
kmod-mac80211-hwsim
wpad

This is the package directory for Barrier Breaker / BRCM 2708 --
http://downloads.openwrt.org/barrier_breaker/14.07/brcm2708/generic/packages/base/

7. You end up with a rat nest of wires: 2x Power(rpi & dsl modem), 1x
Network (dsl modem to rpi), 1x Wireless extension cable(optional), and no
straightforward way of diagnosing/rebooting the system for non-technical
people.

All in all, it wasn't worth it to use Raspberry Pi for this project, I
should have gotten TD-W8961ND and saved myself a whole lot of time, however
the combination of Raspberry PI + OpenWRT offers a lot of potential:
 * Once everything was running further setup was a breeze, the same
hardware can be used for NAS, although SAMBA and NTFS have severe
limitation on Raspberry PI
  * For VPN, SSH, CUPS and  other tasks that require more
CPU/Memory/Storage than consumer router can offer (free memory or cpu never
went below 94% as  I was testing out the set up), I was using 48MB out of
3.6GB of storage on main partition. (on a $5 SD card)
  *  The combination Network port/USB/WIFI   is a relatively inexpensive
way to either put hardware that only supported Ethernet on wireless
network, or to add network capabilities to older plotters/scanners/printers.

So if any of these sounds good, the steps to put a Raspberry Pi-powered
OpenWrt are the following:

1. Install SD image on SD Card
2. Connect to ethernet port and set up subnet
3. Configure wireless, while using your laptop's wifi/eth1 connection to
get all the drivers/troubleshoot wireless hardware
4. Unplug ethernet and connect to RPI box through wifi, make sure that both
web interface and SSH is accessible
5  Backup.
6. Move eth0 interface from Lan to Wan group.
6. Configure Wan Interface
7. (Optional), Unplug Raspberry Pi, resize root partition on SD card from
the host machine using (fdisk/resize2fs) or Parted
8. Backup
9. Done

Alex.


On Wed, Nov 5, 2014 at 6:47 AM, Scott Allen <mlxxxp at gmail.com> wrote:

> On 4 November 2014 23:15, Alex Volkov <avolkov at gmail.com> wrote:
> > I just need dig up a ethernet crossover cable, which I prematurely
> relegated
> > to be a thing of the past.
>
> Are you sure you need a crossover? Almost all ethernet ports are
> auto-sensing these days. The TD-8616's and the Raspberry Pi's both
> are.
>
> --
> Scott
>
>
> ---
> GTALUG Talk Mailing List - talk at gtalug.org
> http://gtalug.org/mailman/listinfo/talk
>
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