How To Test Apple No-access
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 address, such as 67.88.28.163, or an IPv6 address, like 2000:401c:d69d:b6b4:3606:a519:dddf:93f8. You can verify this information by visiting https://test-ipv6.com/. However, relaying these addresses to individuals who are not tech-savvy, or even identifying MAC addresses like c4:a7:b0:8c:f2:74, can be prone to errors and quickly become complex. Furthermore, it does not provide any historical data, especially when past issues arise.
Navigating the World Wide Web
In order to reach a webpage, such as https://heathcote.com, you first connect to a DNS server to convert the host portion (heathcote) combined with the Top Level Domain (com) of the URL to an IP address, like 86.158.159.190. Your computer and browser also transmit their type with every web request, such as Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts).
The Significance of Default Gateways
Your default gateway is typically an automatically configured address via DHCP. You are assigned a default gateway, such as 172.19.83.204 (although they generally end in .1 or .254 depending on the scope size), and this is the destination where your computer forwards all its traffic to be routed. For IPv6, we elaborate on how-to-fix-ipv6-connectivity/, but you can verify this 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 172.19.83.204 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 fe80:3bdf:d66c:b518:c8b2%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): {230.192.156.176, 149.238.60.103}
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 c4:a7:b0:8c:f2:74
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 f9:ff:e6:9c:d6:2d
}
Solve Connectivity Issues for Wired and 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 Tips for Apple macOS / OSX Devices
Regardless of whether you are using OSX/macOS versions like 10.13.3, 11.6.8, or 12.2.9, there are various troubleshooting tools available. However, these manual procedures and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that embrace remote work and the concept of working from anywhere (WFA).
Useful Built-in Scripts
One valuable tool for OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI and can also generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs related to wireless issues, although many of these are only relevant to a specific point in time, similar to 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, you can usesudo /usr/bin/sysdiagnose and it will display 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. Keep in mind that the file sizes are approximately 300MB.
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