Tag: linux

Disabling Wireless at Login on Ubuntu 10.10

This topic may seem like an odd thing to want and try and do, but for the machines I use that have wireless, I don’t want it enabled by default.  One is a desktop that just has a wireless network adapter to run Kismet and the other is a work laptop that spends 99% of it’s time with a wired connection plugged in.

While I enjoy the ease of Ubuntu’s ease of configuring wireless, there is actually no easily exposed setting to keep Network Manager from enabling wireless networking when you login.  After much digging, I found an answer here, but it’s not very elegant.

If you scroll down to what is currently the second to last post, you’ll find a post by tp42 talking about how to use the dbus-send command to make this happen.  The actual command itself is:

dbus-send --system --type=method_call --dest=org.freedesktop.NetworkManager /org/freedesktop/NetworkManager org.freedesktop.DBus.Properties.Set string:org.freedesktop.NetworkManager string:WirelessEnabled variant:boolean:false

The post goes on to detail how to add it into the commands that get run when you log into the default Ubuntu desktop session.

Ideally, this should be a setting you can easily configure so you don’t have to run a command to disable it when you log in, but it does get the job done.

Bridging Tweaks for libvirtd on Ubuntu Desktop 10.10

Having recently dual-booted my main desktop system with Ubuntu 10.10 64-bit, I decided to setup virt-manager to handle KVM virtual machines.  While I don’t have a current use for VMs other than to play around with things as I run into them, I wanted them to be able to talk to other physical machines on my network w/o adding another hop into my internal network.

Therefore, I needed bridging such that virtual machines were assigned IPs (statically or dynamically) in the same subnet as my main desktop. To do this, I followed steps 2.1 and 2.2 from KVM Networking – Community Ubuntu Documentation guide.

Once I did this, everything seemed happy.  However, I noticed that the default bridged network of 192.168.1.x and the default bridge interface virbr0 were still being created, even after restarting libvirtd.  Additionally, this was causing dnsmasq to be started on the system.  With the bridging method I’m using,  there’s no need for that since the virtual machines can reach the name server on my network.  A little more research showed that essentially both problems here were the result of the symlink /etc/libvirt/qemu/networks/autostart/default.xml . Once I removed that, libvirtd was no longer using them, but it hadn’t shut them down.  A little brctl and kill love and all was well again in the universe. :)

Using Munin to Monitor My Comcast Cable Modem

Over the last 6 months or so, I’ve had problems with my Comcast Internet service intermittently cutting out every so often.  As the end user, what I’ve noticed is packet loss,  sometimes it’s a small amount over a short amount of time (minutes), others a large amount over a long amount of time (hours).  Initially the issues were few and far between, so I didn’t give it much notice.  However in the last month or so, it’s become a lot worse (once or twice a week).

I had initially setup Smokeping to monitor when problems started happening.  I had it ping the inside IP of my router, the private IP of the cable modem and the next hop route my router is given in it’s DHCP lease.  It helped me make sure the cable modem was up when I started having packet loss.

While this was nice to know when it was happening, it doesn’t really give you any data that helps with the why.  When I would call Comcast Tech Support, they could confirm the levels on my cable modem weren’t in desirable parameters, but I didn’t get the feeling the knew what they were (or recording them).  Then last week I ran into Jeff Forman’s post about how he was monitoring the signal to noise ration with a custom Munin plugin he had written.

Since I had just started playing with Munin and was looking for a coding type project to work on, I decided to bust out my horribly rusty Perl skills and write my own plugin.  Now I have purdy graphs that look like:

In case this plugin might be useful to you, I’ve made it available here at Github.

Copyright © 1996-2010 weeve.org. All rights reserved.
Jarrah theme by Templates Next | Powered by WordPress