Reflections // Images And Words

Hi Folks,
A while back, I upgraded my Mac OS X Leopard to Snow Leopard and encountered some strange behavior which did not allow me to authenticate anymore. This lead to very ugly situations where no software could be installed anymore (since the dialog didn’t fire up to enter the password) and some settings could not be changed.

Some installs later, I figured it was a Problem with the alternative keyboard layout I’m using. This particular layout has been put together by Jan & Nils [1] and puts the German Umlauts on some of the keys by utilizing the option key. The problem arose when the alternative German Umlaut keyboard Layout had been installed.

For a solution see the entire article.

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This is a translation of the Hetzner Dokuwiki Article “Xen mit Routing-Setup und zusätzlicher (interner) Bridge” [1] which I mentioned in my last post about XEN Networking [2].

[1] http://wiki.hetzner.de/index.php/Xen_mit_Routing_und_Bridge
[2] http://www.henningweiler.de/?p=85

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Hi there,

in the ‘old days’ I’ve been using the Exim MTA and just found a few helpful commands, which I thought might help some people also. Here we go…

Count frozen messages in mail queue:
exim4 -bpr | grep frozen | wc -l

Remove all frozen messages from the mail queue:
mailq | awk '/frozen/ { print $3 }' | xargs exim4 -Mrm

Remove ALL messages from the mail queue:
mailq | awk '/<>/ {print $3}' | xargs exim4 -Mrm

That’s it…

Cheers!

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Hi Everybody,

in order to setup a new server, I had to deal with this more or less troublesome topic. I want to give everybody a hint who is facing trouble with this.

The Setup:
- Debian Lenny (Kernel 2.6.26-2-xen-amd64) 64 Bit host and 64 Bit guests
- xen-hypervisor 3.2-1

The Goal:
I. have a directly routed interface for the public IPs
II. create a virtual LAN between the domUs
III. let the hosts on the virtual LAN talk to the outside world (those are mostly the domUs, which do not have a public IP)

First, for I. and II. go ahead and apply the tutorial in [1]

In addition to that, I had to perform the following operations:
edit /etc/xen/scripts/vif-common.sh and add the two lines indicated

vifname=$(xenstore_read_default "$XENBUS_PATH/vifname" "")
if [ "$vifname" ]
then
if [ "$command" == "online" ] && ! ip link show "$vifname" >&/dev/null
then
do_or_die ip link set "$vif" down ### ADD THIS LINE
do_or_die ip link set "$vif" name "$vifname"
do_or_die ip link set "$vifname" up ### ADD THIS LINE
fi
vif="$vifname"
fi

Ok, now there is something you should keep in mind:
While editing your domU config be sure to keep the vifname parameter SHORT!! I called it ‘mysql-mirror-vif-br’ which was way too long, which then resulted in a non-starting script. The script did not tell me anything. Not on stdout not in the logs. Now it’s ‘mymirr-vif-br’ which is fine.

For III. do the following for every IP you want to have internet access from the inside of the respective domU:

iptables -t nat -A POSTROUTING -o eth0 -s virtualLanIP/32 -j MASQUERADE

Hope this helps someone.

Cheers!

[1] Hetzner Dokuwiki: http://wiki.hetzner.de/index.php/Xen_mit_Routing_und_Bridge

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