Category: Cisco
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NAT’s interaction with DNS answers
Recently I was troubleshooting some odd DNS results between 2 customers that have a B2B connection. The DNS record in question existed in the wild on the internet and resolved to 113.129.255.98 (all IP’s have been randomized using https://onlinerandomtools.com/generate-random-ip for anonymity). Customer A resolved to 192.168.20.5 on their end of the link and Customer B…
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Securing the wired network with 802.1X
This post covers an innovation project I did to secure the wired network at a shared conf center with 802.1X. Every few months we had to disable the wired network in order to prevent non-employees from being able to get online. This was not scalable, was prone to human error, and scheduling confusion. I planned…
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NTP redesign
This post is about a bug that affected NTP (Network Time Protocol) and our redesign of the environment bypass the issue. In this environment the core Cisco 7604 IOS routers were the NTP stratum 2 servers (x.x.x.123 because fun with port numbers). The IP was an HSRP standby IP. There were several downstream Linux…
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Guest wifi and branch backup VPN redo
This post is about a situation I ran into a while ago and records my configs and testing for converting from a PBR setup to VRF on a Cisco 881 router with a diagram at the end. Through a combination of configs involving PBR (Policy Based Routing) AKA Source Routing (as opposed to standard Destination…