Posts in 2020

  • Troubleshooting a Duplicate OSPF Router ID

    Wednesday, January 29, 2020 in Troubleshooting

    Keywords: Troubleshooting, OSPF, Router ID, MPLS, VPLS Introduction I ran into an strange issue today. The problem was reported as “can’t upload on a speed test”. I started looking into the reported speed test issue by doing my …

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Posts in 2015

  • Running Smokeping on Jessie

    Thursday, September 10, 2015 in Troubleshooting

    I recently went thru the process of upgrading most of my virtual machines from Debian Wheezy to Debian Jessie. One of the changes that affected quite a few things was the upgrade from Apache 2.2 to 2.4. One of the packages that is affected by this …

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  • virtio NIC on OpenBSD under KVM

    Sunday, April 12, 2015 in Troubleshooting

    I’ve been running at a new location for about a month now. My setup is a little different than it was previously. Instead of a 2nd physical server in front of my VM host as firewall/ACLs, I’ve now got a virtual machine doing …

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  • Sleep Talking

    Tuesday, February 10, 2015 in Troubleshooting

    This is a write up of an issue which I experienced on one of my networks. It is in response to When Good NICs Do Bad Things: A Blast of IPv6 Multicast Listener Discovery Queries posted on The problem started early on a Friday …

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  • Does Everything Still Work?

    Wednesday, February 04, 2015 in Troubleshooting

    Does everything still work? This is a question often asked after changes in your environment. Whether its routing/switching changes, firewall rule set/policy changes, or software upgrades, having a pre-defined set of tests which should all pass makes …

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Posts in 2014

  • Troubleshooting ICMPv6 with tcpdump

    Thursday, October 23, 2014 in Troubleshooting

    I’ve previously written about my OpenBSD PF firewall in front of my VM server at my colo. I had a firewall rule which used the following variable: icmp6_types="{ 2, 128 }". This wasn’t working properly on the LAN side, and I had …

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  • Internet Connection Sharing

    Thursday, October 16, 2014 in Troubleshooting

    I should start this off by saying that I contemplated much longer titles for this article, but kept it short for URL uniformity. The longer/longest version was: Internet Connection Sharing, Tracking Down Rogue DHCP Servers, and why DHCP Snooping …

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  • Strange SNMP SetRequest Traffic

    Monday, September 15, 2014 in Troubleshooting

    The Internet Storm Center had an interesting diary entry up today which I was able to independently confirm quite easily in under 5 minutes. Watching the traffic for a longer period of time became rather interesting. Here is a packet capture across a …

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  • iPerf UDP

    Sunday, March 09, 2014 in Troubleshooting

    I set out to test the connection between my house and my development workstation, using VOIP-like settings, and IPv6, just to say I’d done it. client side: $ iperf -c -V -u -b 64k -l 160 …

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Posts in 2013

  • "My Traffic Is Not Reaching The Destination"

    Friday, July 26, 2013 in Troubleshooting

    I ran into a very interesting issue this week troubleshooting a UDP stream that a client was trying to stream from one side of the continent to the other. The client informed me that they would be testing a 200 megabit stream from a remote site over …

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