Blogging About .NET : Networks related

Running IPv6 on a router near you

cchrism — Mon, 09 Oct 2006 04:54:00 GMT

I told you before that I updated my WRT54GL router to DD-WRT. One of the neat things of this new firmware is IPv6 support. In case you do not know IPv6 is the next generation of IP protocol, which addresses a major problem nowadays, the fact that IPv4 addresses will most likely to run out in a few years.

The setup is fairly simple, you enable two radio buttons in the DD-WRT web management interface, setup the RADVD and tunnel configuration according to DD-WRT Wiki and enable IPv6 on your Windows XP / 2003 box. Simple to say, simple to do, but I ran into a few problems, the main one being the fact that I wasn't able to communicate with anything over IPv6 from computers connected to the router. After a little bit of digging I found out that the scripts and configuration on the DD-WRT wiki were a little bit wrong, and with a minor fix I was able to use IPv6 successfully. This made me to write this post as it might be helpful to someone in the future.

In the original startup script V6IPNET variable was wrongly computed along with the netmask on V6IP which I think it should be /48, because 2002:x:y:z:w::1/16 is equivalent of 2002::/16, and the routing table would be wrong as it adds address on br0 interface and route also on br0. Anyway the modified script is presented below, and it works for me:

sleep 5
  WANIP=$(ip -4 addr show dev vlan1 | grep 'inet ' | awk '{print $2}' | cut -d/ -f1)
  if [ -n "$WANIP" ]  then
   V6IP=$(printf '2002:%02x%02x:%02x%02x::1/48' $(echo $WANIP | tr . ' '))
   ip tunnel add tun6to4 mode sit ttl 255 remote any local $WANIP
   ip link set tun6to4 mtu 1280
   ip link set tun6to4 up
   ip addr add $V6IP dev br0
   ip -6 route add 2002::/16 dev tun6to4
   ip -6 route add 2000::/3 via ::192.88.99.1 dev tun6to4
   kill -HUP $(cat /var/run/radvd.pid)
  fi

Additionally, you may want to modify the RADVD configuration to advertise prefix 0:0:0::/48 instead of 0:0:0:1::/64, to match the above script, but it is not necessary, as 0:0:0:1::/64 it is a subset of 0:0:0::/48.

These modifications were inspired from OpenWRT wiki, where I found also an interesting configuration tip on how to make Windows XP more IPv6 friendly, not to discriminate IPv6 protocol by favoring IPv4.

If you are interested in IPv6 (and you should be as the change is near), you can find a lot of links for various operating systems at ManyBytesAgo.

Upgrading the WRT54GL

cchrism — Mon, 02 Oct 2006 03:42:00 GMT

As I was saying quite some time ago I decided to upgrading my router firmware. Originally, I wanted to buy this particular model, due it's upgradeability to a open source firmware. The upgrade was a little bit postponed due the fact my computer decided to stop working so I finally managed to do it. If you ask me which were the primary reasons of the upgrade, well static DHCP allocation and SNMP daemon are in the top list. If Linksys would add these feature in the stock firmware, right now I would not add this post. Static DHCP allocation is a very nice feature these days, as you can reshuffle your network (I mean especially in a more business scenario) without touching all the computers/devices out there, but eliminates the disadvantages of changing the device address without any reasons, or not having a predictable numbering scheme. As I said these are quite important in a business scenario, but even at home if you have more than a few devices it worths. Actually, I had a problem with the stock firmware that if I unplugged the router all the devices would have new addresses that usually are not the same, depending which device was faster to request addresses.

The next feature I do not think requires much explanation: graphing the network traffic is quite essential in pinpointing potential problems, so here it goes.

And the lucky winner was DD-WRT after all. I investigated a little bit over OpenWRT, but I decided to go after DD-WRT, since it seemed to me a little bit more interesting. I agree that both distribution have pretty much the same offerings, and even found that they even want to merge to concentrate the effort.

The upgrade process was plain simple, just followed the Wiki installation tutorial and in about 10 minutes it was completed. I decided to skip the mini version and go directly to the voip version. I found that works perfectly going directly to the bigger version, with the warning that it might not work for some devices/versions, but apparently if it doesn't work it doesn't brick your router. This being said I very happy with my latest DD-WRT v23 SP2, and it seems very stable to me. So, keep up the good work with DD-WRT!

Linksys WRT54GL

cchrism — Tue, 11 Jul 2006 04:40:00 GMT

In case you don't know Linksys WRT54GL is the actual version of one of the most routers that kept the headlines a couple of years ago, since Linksys used some GPL code in their firmware and eventually they were forced to release firmware sources and as a consequence a myriad of open source projects started based on the bits published the firmware. This means that you are no longer forced to use whatever a manufacturer decide to release to public, and if you do not like some part you can customize it. Basically WRT54GL can run a linux distribution of course trimmed down to fit the small amount of memory available.

When I builded my wireless network I decided that this router is the best option, so I bought it. I paired it with another Linksys product a BECMU10 cable modem, a very nice thing of this setup is that the cases are builded to be stacked and they use very little space. Anyway, for 49,99 $ after mail-in rebate I do not think I can find a better wireless router at least now. The stock firmware is good but not the best so I started looking for alternate open-source projects. Well, as much as open-source fan I would I think that due the nature of the things (they are not making any money) the marketing is quite short, if at all. So, right now I could not find a comparative analysis between all major open-source firmware for WRT54 in order to decide which is best for me.

At this stage I oscilate between two different projects: DD-WRT and OpenWRT, and I will try to compare them. As far as I've seen in OpenWRT the WPA(2) support is not free so most likely I will go with DD-WRT, apparently this project has a lot of fans, and I should join it. Do you have other opinions?