How Can I Understand Apple Internet
A Guide to Understanding Internet Addressing
When using the Internet, you are assigned a distinct Public IPv4 or IPv6 address, such as 213.105.204.141 or 2000:151f:963c:4c27:a3c7:92:1e15:9f4f. This information can be verified at https://test-ipv6.com/. However, conveying and communicating these addresses to those who are not technically inclined, or even referencing MAC addresses like fb:58:89:d8:27:76, can lead to errors and complexities. Moreover, this method does not provide any historical data, especially when encountering previous issues.
Navigating the World Wide Web
To access a webpage such as https://haley.org, your device initially communicates with a DNS server, which translates the host portion (haley) and the Top Level Domain (org) of the URL into an IP address, such as 136.101.177.254. Additionally, your computer and browser send specific information with all web requests, such as Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
Understanding the Significance of Default Gateways
Your default gateway is typically an automatically configured address obtained via DHCP, such as 10.124.246.253 (although they usually end in .1 or .254, depending on the scope size). This is where your computer directs all its traffic to be further routed. For IPv6, detailed instructions can be found at how-to-fix-ipv6-connectivity/, and you can verify this on Mac or Linux by executing:
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 10.124.246.253 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 fe80:4cc3:de6e:7eb:c711%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): {169.162.24.46, 134.106.216.89}
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 fb:58:89:d8:27:76
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 ff:ba:ad:83:d3:78
}
How to Resolve Wired and Wireless Issues
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.
Tips for Troubleshooting on Apple macOS / OSX
Regardless of whether your system is running on macOS or OSX, be it version 10.15.4, 11.5.4, or 12.3.3, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a continuous stream of correlated values over a period of time. This is where remote troubleshooting automation becomes extremely useful, particularly for teams that are adapting to remote work and Work From Anywhere (WFA) practices.
Useful Built-in Scripts
One valuable tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the current wireless settings to the CLI. This command can also be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool offers a more comprehensive option for generating a wide range of logs, although many of these logs are only relevant to a specific point in time, similar to wdutil.
To run sudo nohup /usr/bin/sysdiagnose -u & in the background and write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can execute sudo /usr/bin/sysdiagnose and it will provide 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. However, be mindful of the file sizes, which are approximately 300MB.
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