I am starting to run into more environments where ipv6 is showing up. I must admit most of the time, the client wasn’t aware the impact of having ipv6 enabled on hosts can have. Other times the client intentionally had ipv6 enabled and in use.
Either way, I get asked how to perform some of the most basic troubleshooting when a Windows host has both ipv4 and ipv6 on it. I must admit, that the first time I was asked about this a few years ago, it was stumped until I stopped, took a breath and read the ping and tracert help screen , lol. Accessing a webserver using a ipv6 address took a little bit more digging but well worth it since the same questions come up in my classes and troubleshooting engagements.
In this video I cover how to ping, tracert and http using ipv6 addresses and how to force the usage of ipv4 addresses when using a host name.
Every network technician will have a sort of network tool that connects to the network. It can be a packet capture tool, like the IOTA I used in my example, a laptop, etc..
In some scenarios, you might send the tool out with a technician or ship it out to a remote site. If you’re lucky, you can preconfigure a static IP, gateway, etc, and connect to it remotely. But what if you have to rely on DHCP assigned address. If you have time you can work with the DHCP administrator and reserve an IP address, or look through the DHCP database for the device’s Mac address. In my experience, getting multiple departments coordinated to find an ip address can take a while, not to mention, what if it's after hours?
In this video, I use Nmap to locate my Profitap IOTA capture device. All I needed to know was a port number that it has ‘open’. In this case, TCP 3000. As I mention in the video, if you had more than one unit, you would need to know your device’s Mac address. Tip; to have Nmap return the Mac address, you need to be on the same VLAN as the target device. In our case, they had a support computer on that VLAN, but I have also used a remote client computer (with their permission).
Thought it would be a good idea to start a series using the NetworkDataPedia’s theme of ‘knowing your network. Let’s start at layer 1 or the hardware layer.
Unfortunately there is so much that can go wrong at this layer but you will still have a network connection and life will seem fine. I say unfortunately because if the problems would cause an complete outage, you would be forced to address it.
I find that many physical level issues are grouped into a few categories:
Installation and Support
I have many issues caused by installation, support shortcuts. Heres a quick list of what I’ve seen; CAT5 cable wrapped around a welder, RJ45 couplers to combine 2 short cables, unsupported bundle of cables pulling the RJ45 connectors out from the switch, overheating modem in a plastic bag, dirty fibre optic cables and ports.
And that’s just what I can remember at the moment. I’m sure you have a bunch yourselves.
Inheritance
Many times analysts build on to an existing system not knowing or understanding the whole picture. A great example is where I saw half the cable run using shielded twisted pair cabling and the new run was unshielded. When I asked why they wouldn’t continue the shielded cabling, the contractor said, ”no one uses that stuff anymore”. Unfortunately I checked the entire run of shielded cables and in my opinion shielded cabling was required. The client brushed it off and I found out later they had to change the cabling due to ‘excessive errors on the new cable runs’. Oops
When possible, the best way to start at the physical layer is to ‘go for a walk’. Either follow a connection from a host to the network, or verify the installation documentation. In this day of video conferencing and smartphones, you can even do this remotely by having someone walk around with their phone.
I have learned a lot working on ‘network cleanups’ network migrations and installations since there is always a surprise to overcome.
To celebrate my 10th year on youtube and to thank all those who watch, like, share and subscribe i wanted to give you a gift. 2 years ago i created a Wireshark class for Udemy which was very popular.
To celebrate my 10th year on youtube and to thank all those who watch, like, share and subscribe i wanted to give you a gift. 2 years ago i created a Wireshark class for Udemy which was very popular.
