Fix Apple Internet
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 address such as 54.20.112.89 or an IPv6 address like 2000:265e:33ee:3bf4:16ef:c0a1:5b21:a081. Verification of these addresses can be done at https://test-ipv6.com/. However, conveying these addresses to those not experienced in technology, or referring to MAC addresses like 93:9f:18:d0:2d:51, can be prone to errors and can become complex. Moreover, this method does not provide historical data, especially regarding past issues.
Navigating the World Wide Web
In order to access a website, for example, https://morar-jacobs.name, your first step is to contact a DNS server to convert the host portion (morar-jacobs) combined with the Top Level Domain (name) into an IP address, such as 39.47.107.56. Every web request sent from your computer and browser includes its type, for example, Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Significance of Default Gateways
The default gateway is typically an automatically assigned address through DHCP. This could be a default gateway like 192.168.138.1 (usually ending in .1 or .254, depending on the scope size), to which your computer sends all its traffic to be routed. For IPv6, detailed instructions can be found at how-to-fix-ipv6-connectivity/, and on Mac or Linux, the process can be verified by the following command:
IPv4 Routes and the Host IPv4 Route Table (inc. VPN)
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 192.168.138.1 UGScg en0 128.0/1 172.18.12.193 UGSc utun3
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.
default fe80:5cf9:b1c9:9daf:4a5e%en0 UGcg en0 default fe80::%utun0 UGcIg utun0 default fe80::%utun1 UGcIg utun1 default fe80::%utun2 UGcIg utun2 2000::/3 utun3 USc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v6 address space.
Debugging DHCP for both IPv4 and IPv6
To get a look at the low level DHCP configuration (Mac/Linux):
ipconfig getpacket en0
...
domain_name_server (ip_mult): {235.10.126.181, 139.191.234.188}
end (none):
...
So, in the above we are not getting IPv6 DNS servers from the DHCPv4 reply but…
ipconfig getv6packet en0
DHCPv6 REPLY (7) Transaction ID 0x80940b Length 76
Options[4] = {
CLIENTID (1) Length 14: DUID LLT HW 1 Time 668691856 Addr 93:9f:18:d0:2d:51
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 09:95:4c:58:44:0d
}
Resolve Connectivity Issues for Wired or Wireless Networks
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.
Solutions for Apple macOS / OSX Users
No matter which version of OSX/macOS you are currently using, whether it’s 10.12.7, 11.0.5, or 12.3.8, there are various troubleshooting tools available. However, manual actions and scripts alone may not provide a comprehensive set of correlated values over time. This is where automated remote troubleshooting comes into play, especially for teams that embrace remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
One useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the current wireless settings to the CLI and can be configured to generate specific troubleshooting logs. Furthermore, the sysdiagnose tool offers a more extensive range of logs (although much of it is only relevant to wireless settings, similar to wdutil).
By running sudo nohup /usr/bin/sysdiagnose -u &, the tool will run in the background and write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose which will prompt a privacy warning. When not run in the background, it will 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.
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