teh fear

Having seen an interesting post over at the ISC about apache’s interpretation of file extensions, I thought I’d have a quick look into what is happening.
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This may not apply to more recent versions of xen and centos, however, running kernel 2.6.18-xen_3.1.0 on CentOS 4.5 I have found that port redirection doesn’t work as expected.
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I’m a big fan of SkylarEC’s PocketTouch application for the iPhone/iPod touch, it allows me to change volume / skip to a different track without taking the device out of my pocket.

I was quite happy with firmware 1.1.4 on my ipod touch, I had my email accounts set up and even work calendar and contacts through the outlook sync client. Unfortunately, somewhere over the last month outlook sync client stopped working for me, I tried in vain to get it working again but no joy!
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SpamAssassin is a great tool for filtering out spam email from the rest, and spam email is a real pain these days.

spamass-milter is a sendmail filter that can be used to connect spamassassin and sendmail together (it is one of many different ways, others include amavis and procmail).

spamass-milter is fine if it is being used on a mail server that sits at the edge of your network, mail identified as spam can be rejected immediately without your server needing to generate bounce messages – the message is immediately rejected and the server that first tried to deliver the message to you has the problem of bouncing the mail instead.
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when first booting xen most people like me (who like to ignore most ot the manual reading until later) will find a xen warning about the thread local storage libraries and how they access memory in a way that xen makes slow. The warning offers the following advice on how to disable it:
mv /lib/tls /lib/tls.disabled
So, I did this, and rebooted my machine – no more warning about libtls, but mysqld failed to start…

Personally, I prefer to use postgresql, however a lot of web applications use mysql so I need to have it.

One way around the problem is to leave tls in place and cope with the slow emulation the xen will have to perform.
I wouldn’t suggest this to be a satisfactory solution, but it certainly keeps one going whilst hunting for a better solution.

Time to do some reading… oddly enough the xen wiki has just the informationI was looking for, how to build a xen specific glibc, I’ll go into a little more detail.
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Everytime I need to change something on a co-located server (ours are only about 2 miles from the main office, but it is still a pain if one has to go to the site because a server is not booting up) that requires restarting in a new configuration, I’m always worried that something might not work properly and I’ll be left stranded with a broken server.

A few years back linux booting was generally handled by a program called LILO, which involved placing entries in a configuration file (/etc/lilo.conf) and then calling the installer (/sbin/lilo)

And then… rebooting to see if it worked

And if you had a system that was a little out of the ordinary – you either had vast experience with lilo and it was easy (is there anyone who can say this?) or you had lots of failed reboots and a lot of head scratching.

has grub changed this?
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Mounting a loop file that is a filesystem is no problem
losetup /dev/loop0 my_loop_image
mount /dev/loop my_mount_point

or
mount -o loop my_loop_image my_mount_point

BUT, what if my loop image has partitions?
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Creating SSL certificates fo use in https with apache is a two stage process

First one makes a private key
openssl genrsa -des3 -out <name of your certificate>.key 1024
You will be asked for a passphrase (password) for this key
NOTE: Make sure you keep this key safe, and don’t forget the password
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A file, key to the successful boot of many a linux system is the initrd image.

It used to be a simple gzipped loop filesystem, unpacked and mounted by commands similar to
gzip -dc initrd.img > initrd_unzipped.img
mount -o loop initrd_unzipped.img temp_dir
Then files can be tweaked inside ‘temp_dir’, the image is then updated by
umount temp_dir
gzip -9c initrd_unzipped.img > initrd.img
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People often get confused as to how Virtual hosts in apache work, here’s an explanation from my understanding…

Firstly each <VirtualHost XXX> entry requires (unless there is only one virtual host) a corresponding NameVirtualHost XXX entry.

The XXX is effectively what IP address and port apache should be listening on for this set of virtual hosts.

For a lot of people this may just be ‘*’ – every IP and any port that apache is listening on.
If you are running on more than one port (http and https would be different ports) then you will probably want to specify a port too… ‘*:80′ would specify all IP addresses and port 80.
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