Archive

Posts Tagged ‘openwrt’

Curling

November 29th, 2010 subogero Comments off

I’m not referring to the most boring sport EVER. Instead, it’s a command line tool I’ve discovered recently: curl. You specify a URL on the command line (e.g. curl http://napirajz.hu), and it prints the contents to standard output.

Time to write my most popular website ever:

The business case:
Bloody multinational corporations filter the internet. One cannot access inspiring content like http://napirajz.hu. Let’s make it accessible.

The tools:
My OpenWrt router hanging on the internet. I’ll create a mirror site on it, refreshed every day at 5:00 (before breakfast), 9:00 (arriving at the office), 13:00 (after lunch) and 18:00 (before I get home).

The beloved cron daemon will do the timing. And the mirroring? On OpenWrt, one lacks the luxuries or Perl and even the cosy comfort of Bash. One has to make do with the BusyBox versions of the Almquist Shell (ash), curl, sed and wget.

#!/bin/ash
PICS=`curl 'http://napirajz.hu' 2>/dev/null \
| sed -nr 's,^[\t ]*<p><img src=\"([a-z0-9/_.]+)\".+$,http://napirajz.hu\1,p'`
rm -f *.jp*
echo '<html><head><title>subogero napi</title></head><body>'
echo '<h1 align="center">subogero napi</h1>'
echo '<hr>'
for i in $PICS; do
 wget $i
 echo $i \
 | sed -r 's,^.+/([a-z0-9_]+)(\.[jpeg]+)$,<p><a href=\"napi/\1\2\">\1</a>,'
done
echo '<hr>'
echo '(c) CC - Mer&eacute;nyi D&aacute;niel'
echo '<br>Eredeti: h t t p : / / n a p i r a j z . h u'
echo '<p>Friss&iacute;tve:'
date "+%Y.%m.%d %H:%M"
echo '</body></html>'

See the result at http://subogero.dyndns.org/git/napi/

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Extend OpenWrt

November 9th, 2010 subogero 4 comments

An OpenWrt router needs to be extended a bit to run big stuff. For instance to build a git-hub. The installed size of git is 91MB. One has an external USB HDD, of course, but what is the right way to do it? The forums are full of extroots and opts and similar stuff. I think they are all evil.

Extroot seems to involve compiling custom firmware images, while /opt brakes the nice Unixy directory structure (standard locations of programs, libs and daemons). There must be a better way:

Mount a partition of an external USB HDD to /usr

Just think about it. The really big files go to /usr/bin /usr/sbin and /usr/lib almost exclusively. Only small stuff goes to /etc, like config files and daemon startup scripts.

Today my theory was confirmed by practice. It’s very simple. These are the important steps:

1. Create an ext3 partition on your HDD just for this purpose

I actually did the partitioning before, on my normal Ubuntu laptop. It’s 2 GB and it’s called /dev/sda2 on the router.

2. Mount it to /opt temporarily

Create the /opt directory (or whatever else) temporarily and mount your partition into it using LUCI/Administration/System/Mount Points.

3. Copy the entire contents of /usr to /opt

The goal is that, initially, /usr looks the same with or without mounting something into it.

$ cp -dpr /usr/* /opt # preserve symlinks
4. Mount partition to /usr

Unmount /dev/sda2 from /opt, mount it into /usr using LUCI. You can also delete the temporary /opt directory.

5. Update /etc/opkg.conf

This involves OpenWrt’s most mysterious concept, overlay. Changing the line below has no effect except to calm down the worrying router about available storage-size for new packages:

option overlay_root /usr

You’re ready to install anything. As for me, I’ve since reinstalled mc and git. No dirty hacks this time with inserting /opt into PATH and manually creating some symlinks from /usr to /opt/usr. Just installed them like a breeze. My github is up and running again.

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OpenWrt

October 31st, 2010 subogero 2 comments

To cut a long story short, the number of Linux kernels running at home has increased. Again.

This time it’s a TP-Link WR1043ND router managing my new internet connection. And check this: the package came with a copy of the GNU General Public License. We live in a beautiful world!

The first thing I did was to overwrite the factory firmware with OpenWrt. It’s a fantastic thing. At the moment of writing, I’m running the following services on it:

  • USB hard disk with some ext3 partitions attached (big)
  • My own git-hub
  • A home file-server using Samba
  • Transmission bit-torrent client
  • It even has its own domain name

Git was a bit tricky, as it’s big, so it’s installed into /opt, mounted from the USB HDD.

I have a theory, that the real solution to increasing the capacity of such routers is not extroot, not /opt, but mounting a partition to /usr.

But I have not tried it. Yet.

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