Tango Devlopment

Category: System Administration

  • Providing IPv6 DNS resolver data with radvd

    One nagging issue I had with IPv6 was how to distribute DNS server addresses and search lists to my clients.   It took a little research to find the solution.  On IPv4 I had been using DHCP to do this, but DHCP didn’t seem to be right approach for IPv6. radvd can be used to distribute both types of data.  The following article covers setup on Ubuntu and OpenWRT.  The Ubuntu (Debian) examples below should work with any distribution using/etc//radvd.conf to configure radvd. (more…)

  • Setting Up BackupPC on Windows

    My original intent in setting up BackupPC was to be able to backup my laptops. The mainly run Windows, and have a lot of shared files. Therefore I wanted a backup solution which handled de-duplication. BackupPC was just what I needed. I have already posted an article about Setting Up BackupPC on Ubuntu that includes setting up a server.

    This article covers setting up BackupPC on Windows using rsyncd as the protocol.   (I tried using Samba, but didn’t like the results with Windows Home editions.) This is done with an extremely minimal cygwin install available from the BackupPC site on SourceForge.  The backups described here are not designed for bare metal recovery.   They should include all the user’s files, and some of the configuration data for installed applications. (more…)

  • Setting Up BackupPC on Ubuntu

    I recently started to do regular backups of all my systems using BackupPC. It uses the rsync protocol to limit the amount of data transferred during backups. Once the initial backup is done, future backups only need to copy incremental changes. This requires far less resources than other software I have used

    This article covers setting up the server on Ubuntu and configuring backups for Ubuntu and OpenWRT. A future article will cover backing up Windows systems using an rsyncd daemon process. (more…)

  • Implementing IPv6 Part 2

    We are quickly running out of IPv4 addresses. Are you ready for World IPv6 Day on June 8th, 2011? I have prepared my configuration on OpenWRT and Ubuntu. This includes configuring DNS using bind, email using Exim, and a Squid web proxy.

    Having verified that I could establish IPv6 connectivity, I chose to improve my connectivity. This started with getting a tunnel from Hurricane Electric and updating my configuration. I then updated my bind server and Exim mail server support IPv6 addresses. This posting updates and continues from my post on Implementing IPv6 6to4 on OpenWRT.   Review it for information on creating a tunnel and running radvd on OpenWRT. (more…)

  • Transparent Squid Proxy

    Over the holidays, I had a user experience and attempted browser hijacking.  It appeared to have bypassed my squid proxy.   My updated configuration now sends all web access via squid.  The old firewall rules, that allowed direct access to the Internet, have been replaced with a transparent Squid proxy.  This runs on my existing Squid Proxy using another port. (more…)

  • Implementing IPv6 6to4 on OpenWRT

    As the IPv4 addresses begins to run out I finally invested the time to investigate and implement IPV6. As my ISP has not yet announced availability of IPV6 addresses I chose to implement a 6to4 tunnel. This is simple to implement, and currently well supported. My external firewall is an ASUS wireless router running OpenWRT.  As I have a static IP address, my implementation is simpler than is required by a dynamic address.  Support for dynamic IPv4 addresses is not covered here, but this configuration should work as long as your address does not change.

    I initially created a 6to4 implementation without a firewall.  Then to secure my systems I implemented a firewall using Shorewall6-lite.  Until I figured out how to configure the 6tunnel script, I used the command line to bring up the network.  This documentation uses of the 6tunnel script instead of the manual commands.  My configuration does not yet include any IPsec functionality. (more…)

  • Manual networking for KVM

    I found the networking configured by libvirt (KVM) did not allow me to firewall the network as I desired.  I use Shorewall for firewalling, and DNSMasq for internal DNS and DHCP.  After a little experimentation, I found that I could configure Ubuntu to create the network.  This allows me to get a reliable firewall configuration with a virtual DMZ.

    The virtual hosts are assigned to a bridge, and only have connectivity to other networks as defined in the Shorewall configuration.  A single DNSMasq server provides DSN an DHCP services for all virtual servers, as well as the network the server is connected to.  The network and firewall configuration remains consistent even as servers are cycled up and down.  An additional bridge was created to support virtual servers in the DMZ zone.

    This page has been updated in 2019 to reflect changes in the tools.

    (more…)

  • Remote Desktops with VNC and RDP

    I find it useful to have a remote desktop to my Ubuntu systems.   On secure connections I have been using VNC via xinetd.  Connections with xrdp where possible, but it wasn’t launching the desktop for the connection.  For secure terminal connections, I stick with with ssh.  All these connection have a login at the start of the connection. This is how I do it. (more…)

  • Cfengine 2 for Debian and Ubuntu

    Cfengine is a declarative system configuration tool.  This helps apply standards to system configuration. The configuration files specify the desired configuration and the engine applies these specifications to the system.  It is useful to:

    • Distribute configuration files;
    • Install standard packages (including on Debian and Ubuntu with code provided here);
    • Cleanup old files; and
    • Ensure certain programs are/are not running.

    This documentation applies to Cfengine version 2. . The latest version has made significant changes to the scripting structure, but maintains the capability to run the version 2 format files. (more…)

  • Firewalling Google Chat and Skype

    To enable for Internet chat I set up Google Chat and Skype.  My firewall rules have been extremely restrictive with only known and approved services allowed to connect.  Google Chat installed with no noticeable impact to the firewall. Things did not go so well with Skype.

    The installation of Skype resulted in lots of warnings on the firewall.  Outgoing tests worked with only port 80 and 443 open.  Skype’s peer-to-peer approach  requires at least one port be opened incoming and and a large range of ports outgoing.  They specify all ports over 1024 should be open.  Their preferred mode seems to be to use uPnP to dynamically modify the firewall.   They do allow you to attempt to set  fixed incoming port which is also used for some outgoing UDP traffic. (more…)