Entries tagged linksys

Related tags: eepc, gargoyle, gpxe, pxe, router, wrt54gl.

My router serves Debian installer via gPXE

Sunday, 25 July 2010

My Linksys router now serves the LAN with netboot images, allowing the simple installation of Debian GNU/Linux.

I updated /etc/dnsmasq.conf on the router itself to read:

# gPXE sends a 175 option.
dhcp-match=gpxe,175

# serve the "undionly.kpxe" file by default.
dhcp-boot=net:#gpxe,undionly.kpxe

# which will then pull the config via HTTP
dhcp-boot=http://static.steve.org.uk/netboot/gpxe.cfg

Then placed /tftproot/undionly.kpxe in place on the router. This combination of files causes:

  • The machine to netboot via undionly.kpxe (think of this like pxelinux.0.)
  • The file gpxe.cfg to be fetched via HTTP
  • Which in turn loads a simple menu.conf file, again via HTTP
  • At this point the user can select the flavour of Debian installer to run.

I have only one problem - it seems that adding the expected entry to boot locally fails:

MENU TITLE Netboot

LABEL Local.Disk
   bootlocal 0

Update: After a fresh sleep and more trial and error I discovered this works:

LABEL Local.Boot
   KERNEL local/chain.c32
   APPEND -

It gives a temporary warning about invalid sector number - but actually does boot locally by default, on both my EEEPC and my desktop machine.

If you want to snarf my netboot environment you are welcome to mirror :

Why did I do this in the first place? I wanted to install Squeeze upon my EEEPC (now done.)

ObQuote: Nice Cross. How'd you get the blood off?

- Dead Like Me

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My Linksys router now runs Linux and almost provides PXE.

Thursday, 22 July 2010

I've been interesting in running Linux upon my router for a long time, but I never had a really compelling reason to do so. The potential for brickage was always too high to make me want to experiment for the sake of it.

However last night I installed Gargoyle upon my Linksys WRT53GL. Although I have no single compelling reason to do so there were a few things on my mind which made me risk it:

Syslog

I thought it would be nice to log things to my desktop machine.

QoS

I often run rsync to mirror my photographs, videos, and files, to off-site locations. These are then replicated via chironfs.

Being able to use QoS to prioritise SSH traffic, which is the transport I use for rsync, means I don't suffer from laggy connections.

Graphing & Statistics

Having statistics and traffic information is interesting.

Since I've only just installed it I've not had too much opportunity to experiment with it - and my initial forays were not so productive. For example "opkg install tcpdump" failed as the root filesystem wasn't big enough.

However which was to update the router to function as PXE server. I installed the tftpd server:

opkg install tftpd-hpa

Then I added this to /etc/dnsmasq.conf:

dhcp-boot=pxelinux.0,router.my.flat,192.168.1.1

Only after I'd done this did I realise two things:

  • I don't have the space on the router to host the pxelinux.0 file, and the associated Debian netboot installer.
  • Chances are I could just use the built-in TFTP support of dnsmasq. ("enable-tftp" + "tftp-root=/tmp/tftproot".)

Tomorrow, (after visiting the dentist. Uggh) I will experiment with this further. Right now it looks like I have two options:

  • NFS mount the TFTP root, but keep both DHCP+TFTPD running upon the router.
  • Configure the router to load the files from another machine, by updating dnsmasq.conf to read: dhcp-boot=pxelinux.0,random.host.name,192.168.1.xx.

Either way I have to store the files upon another host, due to the constrained space on the router's filsystem. So the question becomes "Which service should I run externally: TFPTD or NFS?".

Running TFTPD, upon my desktop, seems smaller, less of a security risk, and neater. Running TFTPD also avoids issues if I reboot both the router and my desktop at the same time as a stalling NFS mount could prevent a timely router-boot.

ObQuote: Looking for a secret door. Places like this always have a secret door.

- St Trinian's 2: The Legend of Fritton's Gold

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