20 Oct 09 Setting up an LVM filesystem

Setting up an LVM filesystem is quite easy assuming you have the right tools installed and a recent kernel. LVM has a lot of advantages, most notably the ability to take snapshots of the current filesystem – this is why LVM is often used in live database environments.

Assuming a Debian Lenny machine, get the relevant packages. Some may already be installed:  apt-get install lvm2 dmsetup mdadm

In this example, we will assuming that /dev/sda is your boot drive, and that you want to leave it out of your LVM array, but include /dev/sdb and /dev/sdc. Both /dev/sdb and /dev/sdc should be of equal sizes.

Firstly, using fdisk, remove any existing partitions with ‘d’, on /dev/sdb and /dev/sdc, and create one new partition to span the drive. Change the partition type to ’8e’ which is the LVM type.

Now prepare your physical disk for LVM with the ‘pvcreate’ tool:

pvcreate /dev/sdb1 /dev/sdc1

Note that you can reverse this with pvremove. You can also use pvdisplay now to display information on all physical volumes.

Oh – you do realie that you can use /dev/mdX just as easily to create LVM on your RAID devices?

Now, we need to create a ‘volume group’: vgcreate myvg /dev/sdb1 /dev/sdc1

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Tags: dd, ext3, kernel, Linux, lvcreate, lvdisplay, lvm, lvremove, mkfs, mount, pvcreate, pvdisplay, pvremove, resize, tar, vgcreate, vgdisplay, vgremove, xen

19 Oct 08 Exim, MySQL, Courier IMAP, Courier POP3 & Spamassassin – vdomain and vuser set up.

There’s a couple of guides out there on how to set up Exim, MySQL, Courier and Spamassassin in a virtual user environment but I thought I’d put together a high level basic guide myself.

My installation is running on debian etch 4.0 stable (2.6.18-6-686)

As this is a vdomain/vuser setup, you will not require a system shell/login for the users you add.

To start off, just install the packages you’ll need with apt-get:

Now if you already have exim4-* installed which is the default, you have two choices. We want to install our own exim version from source but without breaking the repository. The choices are to either just rename exim4 to exim4.old and then create your new exim install, or alternatively create a dummy empty exim4 package remove exim4-* and install your dummy package. This will resolve the dependancies issue in the package manager. Neither method is particularly clean – I have installed a dummy package personally and removed the real exim4 set of packages.
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Tags: courier, courier-authlib-mysql, courier-imap, courier-pop, courier-pop3, exim, exim4, make, make install, MySQL, source, spamassassin, spamc, spamd, tar, vdomain, vuser

16 Sep 08 NetCat tutorial for Linux & Windows, HOWTO, nc

I wrote this article some time ago, but thought I’d publish it here for reference.

This text is dual licenced under the GFDL and GPL

There are two known versions of netcat. The version of netcat used here is the original Avian Research version. Not the newer GNU release

Discuss this page here

Contents:

- Netcat Basics - 1

- What is Netcat? - 1

- Netcat Syntax - 2

- Netcat Installation - 3

- What are the most basic uses? - 4

- Simple File Transfer - 4

- Tar - 5

- UDP - 6

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Tags: advanced uses, command prompt, command shell, cryptcat, inetd, internetworking, ipv6, Linux, nc, nc11nt, netcat, netcat installation, netcat syntax, networking, proxy, proxying, scanning, simple file transfer, socket, spoofing, syslogd, tar, tcp, udp, windows