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 …
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 …
virtio NIC on OpenBSD under KVM
Sunday, April 12, 2015 in Troubleshooting
I’ve been running ciscodude.net 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 …
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 packetpushers.net. The problem started early on a Friday …
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 …
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 …
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 …
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 …
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 …