How Do You DiagnOSe Apple Internet Connection
Understanding How Internet Addressing Functions
When using the Internet, you are assigned a Public IPv4 address, such as 188.22.151.227, or an IPv6 address like 2000:8d8e:a452:f2ef:9830:dded:87be:f638. You can verify this by visiting https://test-ipv6.com/. However, conveying these addresses, including MAC addresses like 6f:9b:6e:95:4b:97, to those who are not technically inclined can be prone to errors and can become complex. Moreover, it does not offer any historical data, particularly when previous issues occurred.
Navigating the Internet
When accessing a website, such as https://jakubowski.name, the first step is to contact a DNS server to convert the host portion (jakubowski) and the Top Level Domain (name) of the URL into an IP address, such as 57.36.206.130. Every time your computer and browser send a web request, they actually transmit their type, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
The Significance of Default Gateways
The default gateway is typically an automatically configured address through DHCP. Usually, a default gateway looks something like 192.0.0.85 (although they typically end in .1 or .254 depending on the scope size) and is where your computer directs all its traffic to be further routed. For IPv6, you can explore more detailed information on how-to-fix-ipv6-connectivity/ or check on Mac or Linux using:
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 192.0.0.85 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 fe80:38b6:fa76:2cc5:1f60%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): {126.195.183.143, 250.40.239.62}
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 6f:9b:6e:95:4b:97
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 19:71:2a:5a:a8:cd
}
Solution for Resolving Issues with Wired or Wireless Connections
When transmitting data to your router, you may use either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Methods for Apple macOS / OSX Users
Regardless of the version of OSX/macOS you have, whether it’s 10.14.7, 11.3.8, or 12.3.7, there are various troubleshooting tools available. However, these tools do not provide a series of correlated values over time, which is a significant limitation. This is where automated remote troubleshooting becomes valuable, especially for teams that embrace remote work and Work From Anywhere (WFA).
Effective Built-in Scripts for Troubleshooting
A very 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 generate specific logs for troubleshooting. Moreover, the sysdiagnose tool can be used to generate a wide range of logs, although many of them are only relevant at a specific point in time, 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 &. If you prefer to run it interactively, you can use the command sudo /usr/bin/sysdiagnose to receive a privacy warning. When not run in the background, this command should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. It’s important to note that the file sizes are approximately 300MB.
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