How To Fix Apple Issues

The Functionality of Internet Addressing

In the realm of the Internet, individuals can obtain a Public IPv4 address such as 165.246.160.121 or an IPv6 address like 2000:99f3:420a:53e2:12a9:3f92:efeb:8c92. Verification of these addresses can be done here. However, for those not well-versed in technology, conveying these addresses or referencing MAC addresses such as a9:3c:db:8a:c8:d6 can be prone to errors and quickly become complicated. Furthermore, such information does not offer any historical context, especially in the case of past issues.

Navigating the World Wide Web

When aiming to access a web page like https://douglas.name, the first step involves connecting to a DNS server to convert the host portion (douglas) along with the URL’s Top Level Domain (name) into an IP address like 236.181.153.226. Notably, all web requests from your computer and browser are sent with your type, for instance: <br>Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16

The Significance of Default Gateways

Typically, the default gateway is automatically assigned through DHCP, resulting in a default gateway such as 10.108.61.235 (although they usually end in .1 or .254 depending on the scope size). This serves as the destination for all traffic from your computer to be routed. For IPv6, a comprehensive guide can be found here. Alternatively, you can check on Mac or Linux with the following code:

### 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  10.108.61.235    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:c8c0:b923:d6c8:e46a%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): {162.57.201.52, 196.199.89.47}
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 a9:3c:db:8a:c8:d6
  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 48:58:27:5a:5d:35
}</pre>




## Resolve Issues with Wired or Wireless Connection
When it comes to transmitting data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
### Troubleshooting Tips for Apple macOS / OSX
Irrespective of the version of OSX/macOS you have, whether it's ```10.15.7```, ```11.1.7```, or ```12.3.2```, there are various tools available for addressing issues. However, the manual actions and scripts don't provide a set of correlated values over time. This is where automated remote troubleshooting becomes extremely valuable, especially for teams that have adapted to remote work and Work From Anywhere (WFA) setups.
#### Helpful Built-in Scripts
One of the useful tools on OSX/macOS is ```sudo wdutil info```, 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 variety of logs, although many of them are only relevant to a specific point in time in relation to wireless, similar to wdutil.

To run ```sysdiagnose``` in the background and write logs to ```/var/tmp/<blah>.tar.gz```, you can use the command ```sudo nohup /usr/bin/sysdiagnose -u &```. If you prefer running it *interactively*, you can use the command ```sudo /usr/bin/sysdiagnose```, bearing in mind that it 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. However, beware of the file sizes, which 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=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>|
|<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>|

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