When using the Internet, it is possible to obtain a Public IPv4 address such as 225.102.115.32
or an IPv6 address such as 2000:4af3:e8e6:ef5f:dc38:f765:208c:2d09
. This information can be verified by visiting https://test-ipv6.com/. However, explaining or conveying these addresses, as well as MAC addresses like a7:ea:20:d4:e6:9a
to individuals who are not technically inclined can be challenging and prone to errors. Furthermore, this does not provide any historical data, particularly with regards to past issues.
In order to access a website such as https://heidenreich-emard.name, the initial step involves contacting a DNS server to convert the host portion (heidenreich-emard) along with the Top Level Domain (name) of the URL into an IP address, for instance 43.106.58.135
. Interestingly, your computer and browser automatically communicate their type with every web request, using a format such as Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)
.
By default, your gateway is typically an address that is automatically set up via DHCP. Examples include default gateway addresses like 10.105.58.19
(usually ending in .1 or .254 depending on the scope size). This is where your computer directs all its traffic in order to be routed further. More detailed information on IPv6
connectivity can be found in our in-depth article on how-to-fix-ipv6-connectivity/. On Mac or Linux systems, the default gateway address can be verified using the following command:
ip -6 route```
### 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 10.105.58.19 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:ed7e:ed18:c00e:32d1%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): {33.104.238.161, 63.147.128.153}
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 a7:ea:20:d4:e6:9a
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 2a:14:a0:29:37:ae
}</pre>
## Resolving Network Connectivity Issues for Wired and Wireless Setups
When it comes to transmitting data to your router, you may be employing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
### Troubleshooting Tips for Apple macOS / OSX Users
Regardless of whether your system is running on OSX or macOS, whether it's version ```10.15.3```, ```11.4.7```, or ```12.0.9```, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a continuous set of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that are embracing remote work and Work From Anywhere (WFA).
#### Utilizing Built-in Scripts for Assistance
One highly useful tool on OSX/macOS is the ```sudo wdutil info```, which provides a dump of the current wireless settings to the CLI and can also generate specific logs for troubleshooting purposes. Furthermore, the ```sysdiagnose``` tool can be used to generate a wide range of logs (although much of it is only point-in-time data regarding wireless, just like wdutil).
Running ```sudo nohup /usr/bin/sysdiagnose -u &``` in the background will write logs to ```/var/tmp/<blah>.tar.gz``` for you. If you prefer to run it *interactively* (although there isn't much interaction), you can run ```sudo /usr/bin/sysdiagnose``` and it will issue a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to ```/var/tmp``` or use Finder with Cmd+Shift+G to direct Finder to the path. Just keep in mind that the file sizes are typically around 300MB.
## Possibly Helpful Videos
<link href="/plugins/lity/css/lity.min.css" rel="stylesheet">
<script src="/plugins/lity/js/lity.min.js"></script>
<div class="table1-start"></div>
|Video | Title | Channel |
| :---: | :---: | :---: |
|<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=HEbK-Tignuc" data-lity><img src="https://i.ytimg.com/vi/HEbK-Tignuc/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=HEbK-Tignuc" data-lity>On the Road to Big Sur 2 - Compatibility</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=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=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>|
<center><small>Table 1.0 - Video Help</small></center>
<br>
<div class="table1-end"></div>
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