Fix Mcs Internet Issues

### IPv4 Routes and the Host IPv4 Route Table (inc. VPN)
```netstat -rn -f inet | egrep -i "default|0/1|128.0/1"```

<pre>
0/1      172.18.12.193  UGScg  utun3
default  172.28.180.197    UGScg  en0
128.0/1  172.18.12.193  UGSc   utun3</pre>

**Note:** We are not just looking for the default but also for any VPN that overrides the public v4 address space.

### IPv6 Routes and the Host IPv6 Route Table (inc. VPN)
```netstat -rn -f inet6 | egrep -i "default|2000::/3"```

If you have IPv6 active the above should return at least one route (as per below) via a known interface such as "_en0_ " on a Mac. 

<pre>
default   fe80:afdd:6cfa:9183:8c77%en0  UGcg   en0
default   fe80::%utun0                   UGcIg  utun0
default   fe80::%utun1                   UGcIg  utun1
default   fe80::%utun2                   UGcIg  utun2
2000::/3  utun3                          USc    utun3</pre>

**Note:** We are not just looking for the default but also for any VPN that overrides the public v6 address space.
<br>

## Debugging DHCP for both IPv4 and IPv6

To get a look at the low level DHCP configuration (Mac/Linux): 

```ipconfig getpacket en0```

<pre>
...
domain_name_server (ip_mult): {176.111.105.198, 107.143.67.90}
end (none):
...</pre>

So, in the above we are not getting IPv6 DNS servers from the DHCPv4 reply but...

```ipconfig getv6packet en0```

<pre>
DHCPv6 REPLY (7) Transaction ID 0x80940b Length 76
Options[4] = {
  CLIENTID (1) Length 14: DUID LLT HW 1 Time 668691856 Addr cb:b6:e9:ba:b3:93
  DNS_SERVERS (23) Length 32: 2606:4700:4700::1111, 2001:4860:4860::8844
  DOMAIN_LIST (24) Length 0:  Invalid
  SERVERID (2) Length 10: DUID LL HW 1 Addr 24:96:02:9e:e6:d9
}</pre>




## Troubleshooting Connectivity Issues on Apple Devices
When it comes to sending data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
### Tips for Resolving Connectivity Problems on Apple macOS / OSX
No matter which version of OSX/macOS you're running - whether it's ```10.13.5```, ```11.1.6```, or ```12.2.5``` - there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes essential, particularly for teams that are embracing remote work and the Work From Anywhere (WFA) model.
#### Essential Built-in Tools
One of the most useful tools on OSX/macOS is ```sudo wdutil info```, which provides a dump of the current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Additionally, the ```sysdiagnose``` tool can generate a wide range of logs (although much of it is only relevant to wireless at a specific point in time, similar to wdutil).

To run ```sysdiagnose``` in the background and generate logs at ```/var/tmp/<blah>.tar.gz```, use the command ```sudo nohup /usr/bin/sysdiagnose -u &```. For an *interactive* (albeit minimal interaction) experience, you can run ```sudo /usr/bin/sysdiagnose```, which will display a privacy warning. If not run in the background, it should open Finder in the correct location, or you can navigate to ```/var/tmp``` using Finder with Cmd+Shift+G. Keep in mind that the file sizes will be around 300MB, more or less.

<br><br>
## Possibly Helpful Videos

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|Video | Title | Channel |
| :---: | :---: | :---: |
|<a href="https://www.youtube.com/watch?v=rjE-BEVlS-0" data-lity><img src="https://i.ytimg.com/vi/rjE-BEVlS-0/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=rjE-BEVlS-0" data-lity>Hotspot 2.0   WLPC Wireless LAN Weekly EP 49</a>|<a target="_blank" href="https://www.youtube.com/channel/UCIzBSS46vcqhwmBZ7ZpY-yg" >Wireless LAN Professionals</a>|
|<a href="https://www.youtube.com/watch?v=npVezI4l7tA" data-lity><img src="https://i.ytimg.com/vi/npVezI4l7tA/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=npVezI4l7tA" data-lity>Real World Protocol Analysis   Peter Mackenzie   WLPC_EU Lisbon 2017</a>|<a target="_blank" href="https://www.youtube.com/channel/UCIzBSS46vcqhwmBZ7ZpY-yg" >Wireless LAN Professionals</a>|
|<a href="https://www.youtube.com/watch?v=miRV8qDOKBE" data-lity><img src="https://i.ytimg.com/vi/miRV8qDOKBE/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=miRV8qDOKBE" data-lity>Apples to Apples: An Analysis of the Effects of mDNS Traffic   Bryan Ward   WLPC Phoenix 2023</a>|<a target="_blank" href="https://www.youtube.com/channel/UCIzBSS46vcqhwmBZ7ZpY-yg" >Wireless LAN Professionals</a>|
|<a href="https://www.youtube.com/watch?v=9RzmyNRK9e4" data-lity><img src="https://i.ytimg.com/vi/9RzmyNRK9e4/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=9RzmyNRK9e4" data-lity>Wireless Packet Captures with Multiple Adapters   Yer Yang   WLPC Phoenix 2019</a>|<a target="_blank" href="https://www.youtube.com/channel/UCIzBSS46vcqhwmBZ7ZpY-yg" >Wireless LAN Professionals</a>|
|<a href="https://www.youtube.com/watch?v=v8y-r9JBhmw" data-lity><img src="https://i.ytimg.com/vi/v8y-r9JBhmw/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=v8y-r9JBhmw" data-lity>The Importance of Broadcast/Multicast Filtering in Wi-Fi HD   Arjan Koopen   WLPC EU Budapest 2016</a>|<a target="_blank" href="https://www.youtube.com/channel/UCIzBSS46vcqhwmBZ7ZpY-yg" >Wireless LAN Professionals</a>|

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