Test Apple Issues
The Functionality of Internet Addressing
When it comes to the Internet, individuals are typically assigned either a Public IPv4 address such as 5.150.114.76 or an IPv6 address like 2000:619f:f038:d84b:3964:e1d8:7759:ce37. To verify this, a visit to https://test-ipv6.com/ can be made. Nevertheless, for those who are not technologically inclined, dealing with these addresses, or even referencing MAC addresses like 84:ab:d5:1b:f1:4b, can be prone to errors and quickly become complex. Moreover, this method does not provide any historical data, particularly for past issues.
Navigating through the World Wide Web
When attempting to access a web page such as https://rempel.info, the initial step involves interacting with a DNS server in order to convert the host part (rempel) in combination with the Top Level Domain (info) of the URL into an IP address, like 76.63.86.122. With each web request, your computer and browser transmit their specifications, for instance: Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts).
Understanding the Significance of Default Gateways
Typically, a default gateway is implemented as an automatically configured address via DHCP. Your computer usually receives a default gateway, such as 192.168.118.187 (although they generally end in .1 or .254, depending on the scale of the scope), and this is where all of your computer’s traffic is directed for routing purposes. For more in-depth details on IPv6, an exploration can be undertaken at how-to-fix-ipv6-connectivity/. On Mac or Linux, this can be verified 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 192.168.118.187 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 fe80:1f26:915:e920:9e8d%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): {156.48.86.187, 155.32.4.91}
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 84:ab:d5:1b:f1:4b
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 c7:7b:33:8a:b8:44
}
Resolving Connectivity Issues for Wired and Wireless Networks
When it comes to transferring data to your router, you may be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Solutions for Apple macOS / OSX
Regardless of the version of OSX/macOS you are running, such as 10.14.4, 11.3.7, or 12.0.3, there are various utilities for troubleshooting. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that are adopting remote work and Work From Anywhere (WFA) policies.
Effective Built-in Tools for Assistance
One useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. In addition, the sysdiagnose tool can be used to generate a range of logs, though many are only relevant at certain points in time in relation to wireless, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & will execute it in the background and write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (even though there isn’t much interaction), you can run sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. When running it in the foreground, it should open Finder in the correct location, or you can navigate to /var/tmp manually or use Finder with Cmd+Shift+G to specify the path. Keep in mind that the file sizes are approximately 300MB.
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