How Can I Support MacOS Internet Connection

Understanding Internet Addressing

When using the Internet, you are assigned a Public IPv4 address, such as 140.9.156.173, or an IPv6 address, like 2000:ce77:914b:ba2a:6bab:2dc0:4858:ecdd. To verify these addresses, you can visit https://test-ipv6.com/. However, relaying these addresses, or MAC addresses like 00:a6:2c:f0:3e:64, may become error-prone and complicated, particularly for individuals not well-versed in technology. Moreover, historical data, especially from past issues, is not provided.

Navigating the World Wide Web

Accessing a webpage such as https://braun.com involves initially reaching a DNS server to translate the combination of the host portion (braun) and the Top Level Domain (com) of the URL to an IP address, such as 30.89.86.80. With every web request, your computer and browser indicate its type, e.g.,
Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts).

Significance of Default Gateways

The default gateway is typically an automatically configured address through DHCP. You are assigned a default gateway, such as 192.168.26.163 (often ending in .1 or .254 based on scope size), to which your computer directs all its traffic for routing. A comprehensive guide on IPv6 connectivity in Mac or Linux is available at how-to-fix-ipv6-connectivity/.

### 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  192.168.26.163    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   fe80:1c8d:3b6a:d0e3:dad3%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): {249.94.254.5, 153.208.253.13}
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 00:a6:2c:f0:3e:64
  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 3e:eb:ab:50:0f:5e
}</pre>




## Fixing Connection Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
### Troubleshooting Tips for Apple macOS / OSX
Regardless of whether you are using OSX/macOS ```10.12.3```, ```11.4.3```, or ```12.1.8```, there are a variety of 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 valuable, especially for teams that operate remotely and embrace Work From Anywhere (WFA).
#### Utilizing Built-in Scripts for Assistance
One helpful tool on OSX/macOS is the ```sudo wdutil info``` command, which provides a dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Additionally, the ```sysdiagnose``` tool can be used to generate a wide range of logs, although much of it is only relevant to wireless settings, similar to wdutil.

To run sysdiagnose in the background and write logs to ```/var/tmp/<blah>.tar.gz```, use the command ```sudo nohup /usr/bin/sysdiagnose -u &```. If you prefer to run it interactively, use the command```sudo /usr/bin/sysdiagnose```, which will give a privacy warning. When 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 are approximately 300MB.
## Possibly Helpful Videos

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|Video | Title | Channel |
| :---: | :---: | :---: |
|<a href="https://www.youtube.com/watch?v=7KdhJimuhNw" data-lity><img src="https://i.ytimg.com/vi/7KdhJimuhNw/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=7KdhJimuhNw" data-lity>Securing macOS Big Sur</a>|<a target="_blank" href="https://www.youtube.com/channel/UCg43DP8MdHVcl4rFK_delBg" >Hands-On Mac</a>|
|<a href="https://www.youtube.com/watch?v=VwNYWAxHCgM" data-lity><img src="https://i.ytimg.com/vi/VwNYWAxHCgM/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=VwNYWAxHCgM" data-lity>Secret Mac Boot Commands - Mac Boot Key Combinations</a>|<a target="_blank" href="https://www.youtube.com/channel/UCg43DP8MdHVcl4rFK_delBg" >Hands-On Mac</a>|
|<a href="https://www.youtube.com/watch?v=RslZ4W1EPqk" data-lity><img src="https://i.ytimg.com/vi/RslZ4W1EPqk/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=RslZ4W1EPqk" data-lity>Spotlight on Spotlight - Hands-On Mac 7</a>|<a target="_blank" href="https://www.youtube.com/channel/UCg43DP8MdHVcl4rFK_delBg" >Hands-On Mac</a>|
|<a href="https://www.youtube.com/watch?v=TWzWd_DiaJ0" data-lity><img src="https://i.ytimg.com/vi/TWzWd_DiaJ0/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=TWzWd_DiaJ0" data-lity>Mac Activity Monitor - How to Troubleshoot Your Mac</a>|<a target="_blank" href="https://www.youtube.com/channel/UCg43DP8MdHVcl4rFK_delBg" >Hands-On Mac</a>|
|<a href="https://www.youtube.com/watch?v=JMKi6o9kaZI" data-lity><img src="https://i.ytimg.com/vi/JMKi6o9kaZI/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=JMKi6o9kaZI" data-lity>macOS Big Sur - What&#39;s New in Apple macOS 11</a>|<a target="_blank" href="https://www.youtube.com/channel/UCg43DP8MdHVcl4rFK_delBg" >Hands-On Mac</a>|

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