How Can I Test Apple No-access
Functioning of Internet Addressing
When connecting to the internet, you are assigned a Public IPv4 or IPv6 address. These addresses can be verified through https://test-ipv6.com/. However, relaying such addresses to individuals unfamiliar with technical jargon or even calling out MAC addresses could lead to errors and complexities. Not to mention, there is no provision for historical data, particularly pertaining to past issues.
Navigating the Internet
In order to access a website like https://kunze-bashirian.net, the first step involves reaching out to a DNS server to translate the host and the Top Level Domain of the URL into an IP address such as 132.189.83.154. Your computer and browser also transmit essential information with every web request, including its type, for instance: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
Significance of Default Gateways
The default gateway is typically automatically configured through DHCP and is responsible for routing all outgoing traffic from your computer. Commonly, the default gateway will have an address ending in .1 or .254, depending on the scope size. For IPv6, detailed guidance is available at how-to-fix-ipv6-connectivity/, and a similar check can be performed on Mac or Linux.
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 10.215.100.9 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:d9bf:ef64:8423:aaf0%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): {45.4.143.56, 184.118.56.126}
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 38:8f:25:34:ab:37
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 13:6f:72:c5:2d:21
}
Troubleshooting Connectivity 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.
Tips and Techniques for Resolving Issues on Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.13.2, 11.1.1, or 12.0.8, 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 invaluable, especially for teams that embrace remote work and Work From Anywhere (WFA).
Using Built-in Scripts for Troubleshooting
A very useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI, and can also 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 point-in-time related 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 &. For an interactive (although not very interactive) experience, you can run sudo /usr/bin/sysdiagnose and 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 or use Finder with Cmd+Shift+G to point Finder to the path. Keep in mind that the file sizes are approximately 300MB.
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