Installing a GNS3 Server

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gns3_logoAlthough GNS3 can run local on your computer and you can use VMware Workstation and have the GNS3 appliance. I found it much more stable and predictable to run GNS3 on a dedicated server. Using this type of installation, all the projects, and images are stored on the GNS3 server, so I can install the GNS3 client any computer and get access to the same projects I was working on. You can also have multiple people working on different projects that are on the same server. I find that neat for educational use or if you where helping someone with a project. In this post I’ll walk though the steps needed to set up a GNS3 server.

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Cisco FTD Standalone

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No management centers here, sometimes a standalone firewall is all you need. In this post I have a FTD appliance and there really isn’t a need tie this into Cisco’s Firepower Management Center. So we’ll configure appliance in standalone mode and go through the initial first steps that are required to get it online and walk through Firepower Device Manager. If you worked with Cisco FMC you’ll find its pretty similar, so with introductions out-of-the-way let’s get started!

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Too Many TCP Resets

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So, recently we enforced some firewall rules on a new environment, we did testing of the environment and everything was working as expected. In about 24 hours a lot of traffic from the web infrastructure was being denied and it continued, at first glance it looked like return traffic was being dropped, the web servers were sourcing at port 443 and the destination ports were using dynamic ports (RFC 6335)

No user or application problems were reported when we enforced rules, and we waited additional days to see if anything came up. Nothing came up, the only thing was a spike in amount of syslog messages of dropped traffic coming from the web servers. So from that point it really wasn’t an issue, but I thought it would be interesting to see what was going on. Continue reading →

Configuring Layer Three EtherChannel

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When you want more speed all you need is EtherChannel, EtherChannel can be configured as a layer three logical interface instead of just sitting at layer two. This is very helpful if we are running layer three down to the access layer switches, instead of at the distribution layer. You also could see this in a collapsed core design, we also don’t have to worry too much about STP when we configure EtherChannel’s. The only requirements to use layer three EtherChannels is your switch need is support layer three “routed” interfaces, so with that let’s get started!

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Wireless VLANs

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raisting-sattelit-reception-signal.jpgIt’s been fun four months of 2018 so far and I’m back to talk about Wireless VLANs. With 802.11ax around the corner (2019) I think we all can agree that “weird” connections although less likely have interference isn’t as mobile as a wireless LAN. Also, with 802.11ax the maximum theoretical throughput is 10Gbps! We’re going to need some serious backend infrastructure available to be able to support that type of bandwidth. So, let’s look at configuring a wireless VLANs for our mobile users!

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