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Run an Ubuntu system long enough, and you’ll eventually have a large number of kernels installed. These don’t cause any harm, but they do take up disk space and appear in the GRUB menu at boot. So every now and again, I take a moment and purge the old kernels.

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After my recent adventure with reverse-path filtering, I didn’t expect to see it again so soon. And then I took another look at a long-standing annoyance in our OpenVPN network.

I set up OpenVPN so our offices and laptops could securely access internal resources. This lets me print documents directly to another office, for instance. Or access web-based applications that we don’t make available to the public. Or remotely SSH into a PC and fix a problem. Read the rest of this entry »

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I recently created a very complex network using routers running Ubuntu Hardy. These routers were configured with the following features:

  • failover shared IP addresses using heartbeat
  • routing announcements via Quagga BGPd
  • 802.1q VLAN tagging
  • multiple physical interfaces

During debugging of this network, I encountered an odd scenario whereby traffic coming in from the external interface (eth0) could not reach the IP address of the secondary (inactive) router’s internal interface (eth1, VLAN tagged).


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