How Do You Test Apple No-access
Understanding How Internet Addressing Operates
When using the Internet, one might be assigned a Public IPv4 address such as 45.71.242.30 or an IPv6 address like 2000:9590:5d1f:39e9:e05e:1bab:70b8:b09e. It’s possible to verify this information at https://test-ipv6.com/. However, for those who are not technologically inclined, conveying these addresses or MAC addresses like a5:3d:7a:29:52:94 can be prone to errors and quickly become complex. Furthermore, this method does not offer any historical data, especially from past issues.
Navigating the World Wide Web
When accessing a website such as https://bernier.biz, the first step is to contact a DNS server to convert the host component (bernier) and the Top Level Domain (biz) of the URL to an IP address like 160.101.250.118. Furthermore, the computer and browser transmit its type with all web requests, for example: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
The Significance of Default Gateways
The default gateway is typically an automatically assigned address via DHCP. An example of a default gateway could be 10.18.33.5 (although they generally end in .1 or .254 depending on the scope size), and this is where the computer sends all its traffic to be routed forward. For IPv6, a detailed explanation can be found at how-to-fix-ipv6-connectivity/, but it is also possible to verify on Mac or Linux with:
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 10.18.33.5 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 fe80:8d55:74c0:e7eb:50cf%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): {30.201.8.154, 179.41.1.229}
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 a5:3d:7a:29:52:94
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 e2:90:28:70:ff:0c
}
Resolving Connectivity Issues Over Wired or Wireless Networks
When it comes to transmitting data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Solutions for Apple macOS / OSX
No matter the version of OSX/macOS you are currently using, whether it’s 10.13.3, 11.3.5, or 12.1.2, there are various tools available for resolving connectivity issues. However, these manual actions and scripts do not provide a consistent set of correlated values over time. This is where automated remote troubleshooting becomes valuable, particularly for teams that have adopted remote work and Work From Anywhere (WFA) practices.
Utilizing Pre-Installed Scripts for Assistance
A useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the CLI, and can also be configured to generate specific logs for troubleshooting purposes. Alternatively, the sysdiagnose tool can be used to generate a wide range of logs, although much of the information is only relevant to a specific point in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & will execute the tool in the background and generate logs in the /var/tmp/<blah>.tar.gz location. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose with a privacy warning. When not run in the background, it should open Finder in the appropriate location, or you can navigate to /var/tmp using Finder or use Cmd+Shift+G to point Finder to the path. Keep in mind that the file sizes are typically around 300MB.
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