Disabling User List in GDM (Gnome 3)

In a multi-user environment you really do not want a full list of usernames being displayed in the GDM login screen for security reasons. In order to disable this feature on my Gentoo lab systems running Gnome 3 and GDM I performed the following actions.

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Exploring Layer 2 Network Security In Virtualized Environments – DerbyCon 4.0

I gave a talk this past weekend on part of my Ph.D. dissertation research at the DerbyCon 4.0 “Family Rootz” Computer Security conference in Louisville, KY. Take a look at the following video to view the talk in its entirety. The rest of the conference videos are available here.



Asterisk SIP Trunk Settings – Vestalink

Vestalink is a new SIP trunk provider that has sprung up as a replacement for Google Voice trunking within Asterisk servers. They offer a very attractive pricing plan with 2000 mins/month going for $39.99 per year, and unlimited plans at $49.99 per year! This provides a single DID along with two SIP channels for the possibility of holding two simutanious calls from one account (call waiting). The folks over to Nerd Vittles have written up a great guide to getting the service working with FreePBX, however I was hard pressed to find any documentation on how to get this working under a standard Asterisk server using only the CLI. Applying the Nerd Vittles FreePBX configuration to Asterisk CLI did not work out of the box. After some messing around I was able to sucessfully register my Asterisk server to my Vestalink account, and I have provided generic configurations that should help anyone looking to integrate a Vestalink SIP trunk with a vanilla Asterisk installation.

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Open vSwitch on Gentoo – Setting Up Your First vSwitch

In my last post I outlined how to get Open vSwitch installed on Gentoo from source for version 1.11.0 as well as from portage using version 2.0.0. I also described how to associate Open vSwitch with with Xen based virtual machines. This guide will detail how to build your first virtual switch from scratch and create virtual switch ports associated with the virtual switch that persist upon a reboot of the host machine. The virtual ports can then be used with VirtualBox VMs and other generic applications that can make use of them.

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Installing Open vSwitch on Gentoo (Xen Hypervisor)

The Gentoo ebuild for Open vSwitch does not seem to work with the latest available kernel as of this writing (3.10.7-gentoo-r1). This post is documentation of the process that I performed in order to successfully install Open vSwitch on a Gentoo server running the Xen hypervisor. This guide assumes that you already have a Gentoo environment configured and running with the Xen hypervisor available in portage.

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Endian Firewall – Getting SIP Phones To Work

There are a few things that need to be done on a new Endian Firewall (Community or UTM Appliance) installation in order to get it to play nice with SIP based voice over IP phones. If your phones are registering to an internal VoIP server you should not have any issues, however if your server or SIP provider are external to your network then some settings will need to be modified.

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Gentoo – FTP Server

If you have the need for a FTP server on your Gentoo system, Pure-ftp is a good choice. It is a lightweight, standards compliant, and production quality FTP server that is available in portage.

To install pure-ftp do the following:

emerge -avq pure-ftp

The default use flags should be fine for most installations.

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Gentoo – Zoneminder

The Zoneminder ebuild in the portage tree has been broken for a couple of years now. Here is the process I use to build Zoneminder from source on a Gentoo x86 install:

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AsteriskNow – IPTables Firewall Configuration

In a previous guide I discussed how to setup an AsteriskNow server with Polycom phone support. In this guide I will illustrate how to tighten up your server’s security by using the IPTables firewall already installed in the distribution.

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Linux – ISO Images

ISO images are very easy to manipulate at the command line in Linux. To make an ISO image from a CD or DVD simply insert the disc into the drive and type:

dd if=/dev/cdrom of=filename.iso

This uses the dd command with the input set to /dev/cdrom and the output set to filename.iso. Change these values as necessary. Note that some Linux distros mount the cdrom drive to /media/cdrom.

To mount an ISO image and read it just as it was a CDROM loaded in the tray do the following:

mkdir /mnt/iso
mount -o loop -t iso9660 filename.iso /mnt/iso

The contents of the ISO can now be accessed in /mnt/iso.